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Status of PHELIX laser and first experiments
Abstract
This paper reports on the status of the PHELIX petawatt laser which is
built at the Gesellschaft fuer Schwerionenforschung (GSI) in close
collaboration with the Lawrence Livermore National Laboratory (LLNL), and
the Commissariat à l'Energie Atomique (CEA) in France. First
experiments carried out with the chirped pulse amplification (CPA)
front-end will also be briefly reviewed.
... In fact, the SSGP compressor had already been successfully applied in several PW facilities, such as the Vulcan and the PHELIX PW laser facilities [18,19] which have relatively narrow spectral bandwidth and hundreds femtosecond output pulse duration. So far, there is no report on the application of SSGP compressor in PW with a broad spectral bandwidth. ...
... Figures 9(c) and (d) show that the spatial chirp induced pulse duration broadening at the focal point is also slightly increased as the spectral bandwidth increased. It indicates that SSGP compressor is more suitable for ultrahigh peak power lasers with narrow spectral bandwidths, which had small influence to the final focal intensity and had been proved in several PW facilities [18,19]. ...
... The temporal profiles at the focal point in the experiment clearly demonstrate the feasibility of the SSGP main compressor. The narrow bandwidth lasers with SSGP compressor or similar SSGP compressor had been applied in PW lasers, such as the Vulcan, the PHELIX and the PETAL PW laser facilities [18,19,30], all of which partly enhance the feasibility of the SSGP compressor with a broad spectral bandwidth. ...
A multistep pulse compressor (MPC) based on a single-pass single-grating pair (SSGP) is proposed to simplify the entire multi-petawatt (PW) compressor. Only one grating pair with relatively long perpendicular distance is used to generate the same amount of spectral chirp compared with a four-grating main compressor. As SSGP compressor induces the largest spatial chirp, it can introduce the best beam-smoothing effect to the laser beam on the last grating. When considering the diffraction loss of only two gratings, the total compression efficiency of the SSGP compressor is even larger than that of a four-grating main compressor. Furthermore, the wavefront aberration induced by the SSGP compressor can be better compensated by using deformable mirrors; however, it is difficult or complicated to be well compensated in a four-grating compressor. Approximately 50–100 PW laser pulses can be obtained using this SSGP-based multistage-smoothing MPC with a single laser beam.
... For example, the ultrashort energetic electron beams can be used for injection purposes in accelerators (Umstadter et al., 1996;Reitsma et al., 2001), in femtosecond physics and chemistry (Barbara et al., 1994;Crowell et al., 2004), for generation of bright ultrashort X-ray pulses through Thomson backscattering of a probe laser pulse (Esarey et al., 1993), in technological applications, and in many other fields. Besides, engineering of an ultrashort electron beam with a predefined internal structure (i.e., the beam having fast longitudinal density modulation, which is called microbunching) can be interesting for application in free-electron lasers (Marshall, 1985;Brau, 1990;Saldin et al., 1999), where the microbunching is an inherent feature vitally important for functioning of the device. ...
... Due to progress in super-intense lasers during the last decade (Danson et al., 2005;Neumayer et al., 2005, Zvorykin et al., 2007Kalashnikov et al., 2007;Canova et al., 2007), high-density electron beams with linear dimensions of 10-20 mm became available in laboratories by using table-top laser-plasma accelerators (Mangles et al., 2004;Geddes et al., 2004;Faure et al., 2004;Hafz et al., 2007). Such a high-density electron beam can be additionally accelerated, compressed, and microbunched by a field of another super-intense laser pulse to improve the properties of the electron beam (Kulagin et al., 2006a(Kulagin et al., , 2006b. ...
The evolution of a high-density electron beam in the field of a super-intense laser pulse is considered. The one-dimensional (1D) theory for the description of interaction, taking into account the space-charge forces of the beam, is developed, and exact solutions for the equations of motion of the electrons are found. It was shown that the length of the high-density electron beam increases slowly in time after initial compression of the beam by the laser pulse as opposed to the low-density electron beam case, where the length is constant on average. Also, for the high-density electron beam, the sharp peak frozen into the density distribution can appear in addition to a microbunching, which is characteristic for a low-density electron beam in a super-intense laser field. Characteristic parameters for the evolution of the electron beam are calculated by an example of a step-like envelope of the laser pulse. Comparison with 1D particle-in-cell simulations shows adequacy of the derived theory. The considered issue is very important for a special two-pulse realization of a Thomson scattering scheme, where one high-intensity laser pulse is used for acceleration, compression and microbunching of the electron beam, and the other probe counter-streaming laser pulse is used for scattering with frequency up-shifting and amplitude enhancement.
... The past three decades have seen a significant revolution in terms of the increasing number of high intensity laser facilities around the world. 1 These installations can operate in a single-shot mode with a low repetition rate as a few shots per day. [2][3][4][5] Others, with a much higher repetition rate, can deliver 10s of shots per minute [6][7][8] or even several thousands of laser pulses per second. 9,10 This implies the need for the development of a wide variety of targets, adapted to the unique properties of each of these facilities, in particular targets capable of operating at high repetition rates (HRRs). ...
We present the development of a flexible tape-drive target system to generate and control secondary high-intensity laser-plasma sources. Its adjustable design permits the generation of relativistic MeV particles and x rays at high-intensity (i.e., ≥1 × 1018 W cm−2) laser facilities, at high repetition rates (>1 Hz). The compact and robust structure shows good mechanical stability and a high target placement accuracy (<4 μm RMS). Its compact and flexible design allows for mounting in both the horizontal and vertical planes, which makes it practical for use in cluttered laser-plasma experimental setups. The design permits ∼170° of access on the laser-driver side and 120° of diagnostic access at the rear. A range of adapted apertures have been designed and tested to be easily implemented to the targetry system. The design and performance testing of the tape-drive system in the context of two experiments performed at the COMET laser facility at the Lawrence Livermore National Laboratory and at the Advanced Lasers and Extreme Photonics (ALEPH) facility at Colorado State University are discussed. Experimental data showing that the designed prototype is also able to both generate and focus high-intensity laser-driven protons at high repetition rates are also presented.
... Laser speckles, which are caused by the coherent nature of laser light propagating through the glass surfaces of the laser system, are an additional source of inhomogeneous target irradiation. is effect can be mitigated by two-sided irradiation of the target foil, and it was applied to increase the precision of energy loss measurements in experiments at GSI-Darmstadt [12,13], where two laser systems PHELIX [14] and nhelix [15] are available. In these experiments, the experimental data and two-dimensional simulation of the free electron density demonstrated that the nonuniformities were strongly reduced. ...
The laboratory generation and diagnosis of uniform near-critical-density (NCD) plasmas play critical roles in various studies and applications, such as fusion science, high energy density physics, astrophysics as well as relativistic electron beam generation. Here we successfully generated the quasistatic NCD plasma sample by heating a low-density tri-cellulose acetate (TCA) foam with the high-power-laser-driven hohlraum radiation. The temperature of the hohlraum is determined to be 20 eV by analyzing the spectra obtained with the transmission grating spectrometer. The single-order diffraction grating was employed to eliminate the high-order disturbance. The temperature of the heated foam is determined to be T = 16.8 ± 1.1 eV by analyzing the high-resolution spectra obtained with a flat-field grating spectrometer. The electron density of the heated foam is about N e = 4.0 ± 0.3 × 10 20 cm − 3 under the reasonable assumption of constant mass density.
... The experiment was conducted at the PHELIX Nd:glass (λ = 1064 nm) laser facility at the GSI Helmholtz Centre for Heavy Ion Research in Germany [44,45]. The P-polarized laser pulse was incident on the target at 22.5°, delivering a maximum energy of 210 J in ∼0.4 ps and was focused using a f/3 off-axis parabola to a minimum focal spot of ∼7 µm in diameter. ...
In a recent experimental campaign, we used laser-accelerated relativistic hot electrons to ensure heating of thin titanium wire targets up to a warm dense matter (WDM) state [EPL 114, 45002 (2016)10.1209/0295-5075/114/45002]. The WDM temperature profiles along several hundred microns of the wire were inferred by using spatially resolved X-ray emission spectroscopy looking at the Ti Kα characteristic lines. A maximum temperature of ∼30 eV was reached. Our study extends this work by discussing the influence of the laser parameters on temperature profiles and the optimisation of WDM wire-based generation. The depth of wire heating may reach several hundreds of microns and it is proven to be strictly dependent on the laser intensity. At the same time, it is quantitatively demonstrated that the maximum WDM temperature doesn’t appear to be sensitive to the laser intensity and mainly depends on the deposited laser energy considering ranges of 6×10¹⁸–6×10²⁰ W/cm² and 50–200 J.
... In this work we will show how to implement X-ray phase contrast imaging (XPCI) in the warm dense matter (WDM) and high energy density physics (HED) studies using a laser-induced X-ray plasma source. Our description will be supported with experimental data acquired at the laser PHELiX at GSI [10] in Germany. Some details about the experiment can be found in [11]. ...
The development of new diagnostics is important to improve the interpretation of experiments. Often well-known physical processes and techniques originally developed in unrelated fields of science can be applied to a different area with a significant impact on the quality of the produced data. X-ray phase-contrast imaging (XPCI) is one techniques which has found many applications in biology and medicine. This is due to its capability to emphasise the presence of strong density variations normally oriented with respect to the X-ray propagation direction. With the availability of short energetic X-ray pulses XPCI extends to time-resolved pump-probe measurements of laser-matter interaction where strong density gradient are also present. In this work we present the setup for XPCI tested at the laser PHELiX at GSI in Germany.
... In the following, we report on an experiment carried out in the petawatt area of the PHELIX-laser facility at GSI [38,39]. The experimental setup consisted of Ti-wires with a diameter of 50 μm and a length up to 8 mm. ...
We studied the interaction of a high-intensity laser with mass-limited Ti-wires. The laser was focused up to , with contrast of to produce relativistic electrons. High-spatial-resolution X-ray spectroscopy was used to measure isochoric heating induced by hot electrons propagating along the wire up to 1 mm depth. For the first time it was possible to distinguish surface target regions heated by mixed plasma mechanisms from those heated only by the hot electrons that generate warm dense matter with temperatures up to 50 eV. Our results are compared to simulations that highlight both the role of electron confinement inside the wire and the importance of resistive stopping powers in warm dense matter.
... Here I find it worthwhile to mention that this prestigious category holds a number of publications from Laser and Particle Beams. The list contains highly cited papers in 2007 (Gupta & Suk, 2007;Flippo et al., 2007(Yin et al., 2006Lifschitz et al., 2006), in 2005 Neumayer et al. 2005;Hora, 2005;Badziak et al., 2005;Roth et al., 2005;, and also one already from 2004 (Hora, 2004). We take this as an indication of the high quality of papers submitted and published in this journal. ...
... The theoretical simulation represents that the phase fluctuation is inversely proportional to the pump energy, implying that this phase control method becomes more effective and practical as the pump energy increases. Inertial fusion energy as well as high energy density physics experiments require much higher repetition rates than can be obtained with current high power lasers Batani et al., 2007;Zvorykin et al., 2007;Nobile et al., 2006;Jungwirth, 2005;Danson et al., 2005;Schaumann et al., 2005;Neumayer et al., 2005). The beam combination system using SBS-PCMs would greatly benefit from an increase in pulse repetition rate with high energy/high power operation (Kong et al., 1997(Kong et al., , 2005a(Kong et al., , 2005b(Kong et al., , 2005d(Kong et al., , 2006(Kong et al., , 2007(Kong et al., , 2008Lee et al., 2005). ...
An overview on current trends in stimulated Brillouin scattering and optical phase conjugation is given. This report is based on the results of the "Second International Workshop on stimulated Brillouin scattering and phase conjugation" held in Potsdam/Germany in September 2007. The properties of stimulated Brillouin scattering are presented for the compensation of phase distortions in combination with novel laser technology like ceramics materials but also for e.g., phase stabilization, beam combination, and slow light. Photorefractive nonlinear mirrors and resonant refractive index gratings are addressed as phase conjugating mirrors in addition.
... For 10 years, Dieter Hoffmann was head of the plasma physics department at GSI. During this time he initiated a project to build a high energy laser system at GSI interaction experiments of ion beams with high temperature, high density plasma (Neumayer et al., 2005;Schaumann et al., 2005). Today two laser systems at GSI are in place and they are part of the European Laserlab network. ...
... A very prominent application is laser fusion energy (LFE), which requires very high energy and high power laser output of several megajoules in a few tens of nanoseconds with a high repetition rate around 10 Hz (Nakai & Mima, 2004). However, the current systems in high energy laser facilities, such as NHELIX (Schaumann et al., 2005), PHELIX (Neumayer et al., 2005; Kuehl et al., 2007), PALS (Jungwirth, 2005; Batani et al., 2007; Laska et al., 2006; Torrisi et al., 2008), and Vulcan Petawatt (Danson et al., 2005), are operated with a low repetition rate or a single shot due to the thermal problems of the laser materials. The beam combination method using stimulated Brillouin scattering phase conjugate mirrors (SBS-PCMs) is a promising one for the high energy output with a high repetition rate (Kong et al., 1997; 1999; Basov et al., 1979; Rockwell & Giuliano, 1986; Valley et al., 1986; Loree et al., 1987; Bower & Boyd, 1998; Riesbeck et al., 2001; Kappe et al., 2007; Ostermeyer et al., 2008). ...
The beam combination method using stimulated Brillouin scattering phase conjugate mirrors (SBS-PCMs) is a promising technique for a high energy and high power laser output operating with a high repetition rate. The two-beam combined system was previously demonstrated with an amplitude dividing method. A four-beam combined laser system with amplitude dividing method is demonstrated in this work, and the phase stabilization experiment of this system is performed using the self phase control and the long-term stabilization technique. The phase differences between the SBS waves are stabilized with λ/30 and the fluctuation of the four-beam combined output energy is 6.16% during 2000 shots (200 s).
... Lasers along with intense particle beams are the main tolls to induce high energy density states in matter. This kind of basic research toward fusion energy would greatly benefit from an increased repetition rate of the experiments (Neumayer et al., 2005; Schaumann et al., 2005; Hoffmann et al., 2005; Hora et al., 2005;). Toward high energy and high power laser, many technique approaches have been taken in various ways, such as diode-pumped laser with gas cooling, electron– beam-pumped gas laser, large-sized ceramic laser, and beam combination laser (Ueda & Takuma, 1987; Kong et al., 1997; Lu et al., 2002). ...
A new concept of laser fusion driver is proposed, which uses a beam combination technique with stimulated Brillouin scattering phase conjugate mirror (SBS-PCM). It is constructed systematically with a cross-type amplifier as a basic unit. In the first part of this paper, we introduce the cross-type laser amplifier using SBS-PCM, with several advantages by experimental results. These advantages are the ideal properties for practical laser fusion driver, such as the perfect isolation of leak beam, the compensation of thermally induced birefringence through the amplifiers, the easy maintenance and alignment insensitiveness, and the freely-scale-up energy. Next, some successful results for the phase control of SBS-PCM are presented, which is one of the main problems in the current beam combination laser using SBS-PCM. Particularly, a new technique for controlling the phase of SBS-PCM, “self-density modulation,” is introduced, which is the simplest ever among those reported. With the advantages of the cross-type amplifier using SBS-PCM and the novel method for controlling the phase of SBS-PCM, the proposed beam combination laser system is presented as the most promising one, which can contribute to the realization of high energy laser that can operate with high repetition rate over 10 Hz, even in the case of huge output energy over MJ.
... Large-scale, high intensity laser installations (Cook et al., 2008;Blanchot et al., 2006;Delettrez et al., 2005;Danson et al., 2005;Dunne, 2006;Miyanaga et al., 2003;Neumayer et al., 2005) can achieve highly relativistic intensities and generate extremely high currents of relativistic electrons in interaction with solid targets. An accurate description of the transport of such high currents of relativistic electrons in dense matter is an important issue for many applications including the fast ignition of thermonuclear fusion targets, radiography of dense opaque objects, cancer therapy, lithography, etc. (Borghesi et al., 2002;Glezos & Raptis, 1996;Mangles et al., 2006). ...
A reduced mathematical model for the transport of high current relativistic electron beams in a dense collisional plasma is developed. Based on the hypothesis that the density of relativistic electrons is much less than the plasma density and their energy is much higher than the plasma temperature, a model with two energy scales is proposed, where the beam and plasma electrons are considered as two coupled sub-systems, which exchange the energy and particles due to collisions. The process of energy exchange is described in the Fokker-Planck approximation, where the pitch angle electron-ion and electron-electron collisions dominate. The process of particle exchange between populations, leading to the production of secondary energetic electrons, is described with a Boltzmann term. The electron-electron collisions with small impact parameters make an important contribution in the overall dynamics of the beam electrons.
... Hence, it can operate at a repetition rate exceeding 10 Hz regardless of the output energy and is easily adaptable to the modern laser technology. This technique is very important for high power laser in inertial fusion research, which are currently constructed or operated already ~Danson et al., 2005; Neumayer et al., 2005!. Kong et al. ~1997, 1999! proposed a promising beam combination laser system ~seeFig. 1 !, using stimulated Brillouin scattering-phase conjugate mirrors ~SBS- PCM! whose output energy can be unlimitedly scaled up by increasing the number of separate amplifiers. ...
Volume 23, Number 1, Pages 55–59, 2005
Below is the complete Reference citation for Neumayer et al. (2005).
Neumayer, P., Bock, R., Borneis, S., Brambrink, E., Brand, H., Caird, J., Campbell, E.M., Gaul, E., Goette, S., Haefner, C., Hahn, T., Heuck, H.M., Hoffmann, D.H.H., Javorkova, D., Kluge, H.-J., Kuehl, Th., Kunzer, S., Merz, T., Onkels, E., Perry, M.D., Reemts, D., Roth, M., Samek, S., Schaumann, G., Schrader, F., Seelig, W., Tauschwitz, A., Thiel, R., Ursescu, D., Wiewior, P., Wittrock, U. & Zielbauer, B. (2005). Status of PHELIX laser and first experiments. Laser Part. Beams23, 87–93.
We present the usage of two-layer targets with laser-illuminated front-side microstructures for x-ray backlighter applications. The targets consisted of a silicon front layer and copper back side layer. The structured layer was irradiated by the 500-fs PHELIX laser with an intensity above 1020Wcm−2. The total emission and one-dimensional extent of the copper Kα x-ray emission as well as a wide spectral range between 7.9 and 9.0 keV were recorded with an array of crystal spectrometers. The measurements show that the front-side modifications of the silicon in the form of conical microstructures maintain the same peak brightness of the Kα emission as flat copper foils while suppressing the thermal emission background significantly. The observed Kα source sizes can be influenced by tilting the conical microstructures with respect to the laser axis. Overall, the recorded copper Kα photon yields were in the range of 1011sr−1, demonstrating the suitability of these targets for probing applications without subjecting the probed material to additional heating from thermal line emission.
Laser-based particle accelerators have been an active field of research for over two decades moving from laser systems capable of one shot every hour to systems able to deliver repetition rates in the Hz regime. Based on the advancements in laser technology, the corresponding detection methods need to develop from single to multiple use with high readout speed. Here, we present an online compact tracker of particles using scintillators with nine resolvable energy levels and a spatial resolution of 3.6 × 3.6 mm² over the whole active area. This paper describes the design and construction of the detector, which is based on pixellated scintillators embedded inside an absorber matrix. The scintillator pixels are fiberoptically coupled to a camera system for online readout and analysis. Calibration with a radioactive source and first experimental data measuring laser accelerated ions at the PHELIX laser at GSI, Darmstadt, Germany, are presented and discussed.
X-ray phase contrast imaging (XPCI) is more sensitive to density variations than X-ray absorption radiography, which is a crucial advantage when imaging weakly-absorbing, low-Z materials, or steep density gradients in matter under extreme conditions. Here, we describe the application of a polychromatic X-ray laser-plasma source (duration ~0.5 ps, photon energy >1 keV) to the study of a laser-driven shock travelling in plastic material. The XPCI technique allows for a clear identification of the shock front as well as of small-scale features present during the interaction. Quantitative analysis of the compressed object is achieved using a density map reconstructed from the experimental data.
X-ray phase-contrast imaging (XPCI) is a versatile technique with wide-ranging applications, particularly in the fields of biology and medicine. Where X-ray absorption radiography requires high density ratios for effective imaging, XPCI is more sensitive to the density gradients inside a material. In this letter, we apply XPCI to the study of laser-driven shockc waves. We used two laser beams from the Petawatt High-Energy Laser for Heavy Ion EXperiments (PHELIX) at GSI: one to launch a shock wave and the other to generate an X-ray source for XPCI. Our results suggest that this technique is suitable for the study of warm dense matter (WDM), inertial confinement fusion (ICF) and laboratory astrophysics.
Reflective diffraction gratings are driving the development of high power chirped pulse amplification technology and high power fiber laser spectral beam combining. Near half-meter (metal) multilayer dielectric gratings, and polarization-independent spectral combining gratings have made a big step.
For achieving practically useful laser fusion energy generation, it is necessary to have a M-J laser system with a repetition rate over 10 Hz. We believe that a beam combination method using stimulated Brillouin scattering phase conjugate mirrors (SBS-PCM) is one of the most practical techniques for achieving the high repetition rate of the high power laser. In this paper, we present the recent results about the beam combination laser, such as SBS reflectivity depending on the mode structure, the cross type isolator, and the phase-locking technique. For the phase-locking technique, especially, the self-phase-locking is proposed and its result is discussed.
We present a summary of recent experiments on focusing of laser target-normal-sheath-accelerated (TNSA) proton beam with a stack of thin conducting foils. The experiments were performed using the Phelix laser (GSI-Darmstadt) and the Titan laser, Lawrence Livermore National Laboratory. The phenomena consistent with self-collimation (or weak self-focusing) of TNSA protons were experimentally observed for the first time at the Phelix laser user facility, in a specially engineered structure ("lens") consisting of a stack of 300 thin aluminum foils separated by 50 μm vacuum gaps. Follow up experiments using the Titan laser obtained results consistent with the collimation/focusing observed in the initial experiments using the Phelix. The Titan experiments employed improved, 25 μm- and 50 μm-gap targets and the new fine mesh diagnostic. All the experiments were carried out in a "passive environment," i.e., no external fields were applied, and no neutralization plasma or injection of secondary charged particles was imposed. A plausible interpretation of the observed phenomena is that the combination of magnetic self-pinch forces generated by the beam current together with the simultaneous reduction of the repulsive electrostatic forces due to the conducting foils inhibits radial expansion of the beam.
Laser technology developments, including construction of a 286-TW Ti:Sapphire laser with a focused intensity of 1021W/cm2, installation of the TIL, prototype of the SG-III, and operation of the SG-II laser are presented. Results of the experiments on hohlraum physics, indirect-drive implosion, Thomson scattering, EOS, and X-ray laser are briefly introduced. Simulations and a code package, LARED, for target physics are outlined.
This paper reviews the basic ideas as well as the latest experimental results obtained in the rapidly emerging field that studies macroscopic thermodynamic parameters and collective phenomena occurring due to exposure of matter to an intense ion beam. Beams of accelerated heavy
ions as a tool to produce extreme states of matter under reproducible experimental conditions have attracted the attention of scientists from around the world. This is largely due to the fact that an ion beam releases its energy into the volume of matter. Importantly, relativistic colliders, being unique tools for probing extreme states of matter, have opened up new possibilities for producing various states of matter, including those exhibiting exotic sets of thermodynamic parameters. The problems addressed by experiments in the field are of fundamental nature and deal with equations of states of supercompressed matter, plasma phase transitions, critical points of metals, anomalous conductivity, noncongruent phase transformations, and atomic physics with strong interparticle interactions.
In inertial confinement fusion implosion experiments with the primary-neutron yield as low as 107, the method of yield ratio is proposed to diagnose the areal density at Shenguang II laser facility. Considering the detection efficiency and the time response, a new detector for detecting the secondary-neutron signal is developed, which locates 50 cm away from the target. According to Monte Carlo N-particle simulation, 5-cm-thick lead shield was placed in front of the detector to shield x rays. In the 2004 experiments, the highest primary-neutron yield is 3.18×106, which is an order lower than expected. Inspite of this fact, a secondary-neutron signal is measured for the first time at the Shenguang II laser facility, which proves the method's feasibility. The method will be used in the experiments at the prototype of Shenguang III laser facility.
Accurate x-ray scattering techniques to measure the physical properties of dense plasmas have been developed for applications in high energy density physics. This class of experiments produces short-lived hot dense states of matter with electron densities in the range of solid density and higher where powerful penetrating x-ray sources have become available for probing. Experiments have employed laser-based x-ray sources that provide sufficient photon numbers in narrow bandwidth spectral lines, allowing spectrally resolved x-ray scattering measurements from these plasmas. The backscattering spectrum accesses the noncollective Compton scattering regime which provides accurate diagnostic information on the temperature, density, and ionization state. The forward scattering spectrum has been shown to measure the collective plasmon oscillations. Besides extracting the standard plasma parameters, density and temperature, forward scattering yields new observables such as a direct measure of collisions and quantum effects. Dense matter theory relates scattering spectra with the dielectric function and structure factors that determine the physical properties of matter. Applications to radiation-heated and shock-compressed matter have demonstrated accurate measurements of compression and heating with up to picosecond temporal resolution. The ongoing development of suitable x-ray sources and facilities will enable experiments in a wide range of research areas including inertial confinement fusion, radiation hydrodynamics, material science, or laboratory astrophysics.
An intense and focused heavy ion beam is a suitable tool to generate high energy density in matter. To compare results with simulations it is essential to know beam parameters as intensity, longitudinal, and transversal profile at the focal plane. Since the beam's energy deposition will melt and evaporate even tungsten, non-intercepting diagnostics are required. Therefore a capacitive pickup with high resolution in both time and space was designed, built and tested at the high temperature experimental area at GSI. Additionally a beam induced fluorescence monitor was investigated for the synchrotron's (SIS-18) energy-regime (60–750 AMeV) and successfully tested in a beam-transfer-line.
High intensity particle beams from accelerators induce high energy density states in bulk matter. The SIS-18 heavy ion synchrotron at GSI now routinely delivers intense Uranium beams that deposit about 1 kJ/g of specific energy in solid matter, e.g. solid lead. Due to the specific nature of the ion-matter interaction a volume of matter is heated uniformly with low gradients of temperature and pressure in the initial phase, depending on the pulse structure of the beam with respect to space and time. The new accelerator complex FAIR (Facility for Antiproton and ion Research) at GSI as well as beams from the CERN large hadron collider (LHC) will vastly extend the accessible parameter range for high energy density states. One special piece of accelerator equipment a superconducting high field dipole magnet, developed for the LHC at CERN is now serving as a key instrument to diagnose the dense plasma of the sun interior plasma, thus providing an extremely interesting combination of accelerator physics, plasma physics and astro-particle physics.
Laser-produced plasmas are often used as bright x-ray backlighters for time-resolved plasma diagnostics, but such backlighters simultaneously generate damaging electromagnetic pulse (EMP). A laser-driven Ar gas jet x-ray source has been measured with magnetic flux B-dot probes to produce 20 times ±37% less integrated EMP in the 0.5–2.5 GHz band than a solid chlorinated plastic foil, while retaining 85% of the laser to ≈3 keV x-ray conversion efficiency. These results are important for future backlighter development, since tailoring target density may provide a way to reduce EMP even as laser power increases.
The start of a new issue in a new year is always an opportunity to look back and to say thank you to the members of the editorial board and the editorial staff who made it possible that we were able to publish four interesting issues in Volume 24 last year. First of all, I want to thank the scientific community for submitting a large number of excellent original research papers to Laser and Particle Beams . In 2006, we were able to publish 71 articles plus editorial material and corrections. The average article in the journal is now 8–9 printed pages, and we have thus achieved the editorial goal to offer the community a place to publish their results without general space restrictions. Authors have accepted this opportunity to present their material with the necessary details. This seems to be very important to readers and authors as well, and we see that for a second consecutive year many articles in Laser and Particle Beams are referenced already during the first year, which is remarkable for a small journal with only four issues per year.
For decades the analysis of interferometry have relied on the
approximation that the index of refraction in plasmas is due solely to the
free electrons. This general assumption makes the index of refraction
always less than one. However, recent soft x-ray laser interferometry
experiments with Aluminum plasmas at wavelengths of 14.7 nm and 13.9 nm
have shown fringes that bend the opposite direction than would be expected
when using that approximation. Analysis of the data demonstrated that this
effect is due to bound electrons that contribute significantly to the
index of refraction of multiply ionized plasmas, and that this should be
encountered in other plasmas at different wavelengths. Recent studies of
Silver and Tin plasmas using a 46.9 nm probe beam generated by a Ne-like
Ar capillary discharge soft-ray laser identified plasmas with an index of
refraction greater than one, as was predicted by computer calculations. In
this paper we present new interferometric results obtained with Carbon
plasmas at 46.9 nm probe wavelength that clearly show plasma regions with
an index of refraction greater than one. Computations suggest that in this
case the phenomenon is due to the dominant contribution of bound electrons
from doubly ionized carbon ions to the index of refraction. The results
reaffirm that bound electrons can strongly influence the index of
refraction of numerous plasmas over a broad range of soft x-ray
wavelengths.
Intense heavy ion beams from the Gesellschaft für
Schwerionenforschung (GSI, Darmstadt, Germany) accelerator facilities,
together with two high energy laser systems: petawatt high energy laser
for ion experiments (PHELIX) and nanosecond high energy laser for ion
experiments (NHELIX) are a unique combination to facilitate pioneering
beam-plasma interaction experiments, to generate and probe
high-energy-density (HED) matter and to address basic physics issues
associated with heavy ion driven inertial confinement fusion. In one class
of experiments, the laser will be used to generate plasma and the ion beam
will be used to study the energy loss of energetic ions in ionized matter,
and to probe the physical state of the laser-generated plasma. In another
class of experiments, the intense heavy ion beam will be employed to
create a sample of HED matter and the laser beam, together with other
diagnostic tools, will be used to explore the properties of these exotic
states of matter. The existing heavy ion synchrotron facility, SIS18,
deliver an intense uranium beam that deposit about 1 kJ/g specific
energy in solid matter. Using this beam, experiments have recently been
performed where solid lead foils had been heated and a brightness
temperature on the order of 5000 K was measured, using a fast
multi-channel pyrometer that has been developed jointly by GSI and IPCP
Chernogolovka. It is expected that the future heavy ion facility, facility
for antiprotons and ion research (FAIR) will provide compressed beam
pulses with an intensity that exceeds the current beam intensities by
three orders of magnitude. This will open up the possibility to explore
the thermophysical and transport properties of HED matter in a regime that
is very difficult to access using the traditional methods of shock
compression. Beam plasma interaction experiments using dense plasmas with
a [Gamma]-parameter between 0.5 and 1.5 have also been carried out. This
dense Ar-plasma was generated by explosively driven shockwaves and showed
enhanced energy loss for Xe and Ar ions in the energy range between 5.9 to
11.4 MeV.
The Prague Asterix Laser System (PALS) research program covers a broad
spectrum of laser–plasma experiments in the range of power densities
of 1014-5 × 1016 W/cm2, aimed
at development and applications of laser plasma-based ion and soft X-ray
sources of plasma based ultra-bright XUV lasers in particular. In parallel
to these two main lines of research, various principal tasks of laser
plasma physics are being studied, such as generation and propagation of
laser-induced shock waves, laser ablation, and crater creation processes
or laser imprint treatment. Results selected of numerous experimental
projects performed at PALS within the period 2002–2004 are surveyed
in the paper, experiments with intense soft XUV laser beams being
highlighted on the first place.
The chlorine He[alpha] radiation of polyvinyl chloride (PVC)
was investigated with respect to X-ray scattering experiments on dense
plasmas. The X-ray source was a laser-produced plasma that was observed
with a highly reflective highly oriented pyrolytic graphite (HOPG) crystal
spectrometer as it is used in current x-ray scattering experiments on
dense plasmas. The underlying dielectronic satellites of
He[alpha] cannot be resolved, therefore the plasma was observed
at the same time with a focusing spectrometer with spatial resolution. To
reconstruct the spectrum a simple model to calculate the spectral line
emission based on dielectronic recombination and inner shell excitation of
helium- and lithium-like ions was used. The analysis shows that chlorine
dielectronic satellite emission is intense compared to He[alpha]
in laser-produced chlorine plasmas with a temperature of 300 eV in this
wavelength range of [Delta][lambda] = 0.07 [Angstrom capital A, ring] ([Delta]E = 43 eV).
The method proposed in this paper allows deducing experimentally the role
of the underlying dielectronic satellites in the scatter spectrum measured
with a HOPG crystal spectrometer. It is shown that the dielectronic
satellites can be neglected when the scattering is measured with low
spectral resolution in the non-collective regime. They are of major
importance in the collective scatter regime where a high spectral
resolution is necessary.
In this paper, we describe the experimental validation of the technique of correction of wavefront aberration in the middle of the laser amplifying chain. This technique allows the correction of the aberrations from the first part of the laser system, and the pre-compensation of the aberrations built in the second part. This approach will allow an effective aberration management in the laser chain, to protect the optical surfaces and optimize performances, and is the only possible approach for multi-petawatt laser system from the technical and economical point of view. This approach is now possible after the introduction of new deformable mirrors with lower static aberrations and higher dynamic than the standard devices.
The minimum irradiance needed to overcome amplified spontaneous emission (ASE) of a seed beam injected into a laser amplifier is evaluated. The treatment is particularly applicable to extreme ultraviolet (EUV) and X-ray laser schemes to inject laser harmonic radiation as a seed into (1) plasma laser amplifiers and (2) free-electron lasers. Simple expressions and calculations are given for the minimum injected irradiance required for amplification of the injected seed beam to exceed ASE from the amplifier, including the effects of gain saturation, assuming one dimensional radiative transfer.
Edward Teller Lectures—Lasers and Inertial Fusion Energy , Heinrich Hora and George H. Miley, eds. Foreword by E.M. Campbell. First edition. Imperial College Press, London, 365 pp. US $63.00 ISBN: 1-86094-468-X
Since 1991, the Edward Teller Medal is awarded to individual researchers in recognition of their respective pioneering experimental or theoretical work in the field of intense laser and particle beam physics, and physics application of high power drivers, which is exactly the field that the journal Laser and Particle Beams covers in great detail. Motivation of this research field is the investigation of properties of high energy density matter with the ultimate goal to achieve inertial fusion in the laboratory under reproducible conditions, and to develop a scientific basis for inertial fusion energy.
This paper presents the laser beam filamentation at ultra relativistic laser powers, when the paraxial restriction on the beam is relaxed during the filamentation process. On account of laser beam intensity gradient and background density gradients in filamentary regions, the electron plasma wave (EPW) at pump wave frequency is generated. This EPW is found to be highly localized because of the laser beam filaments. The interaction of the incident laser beam with the EPW leads to the second harmonic generation. The second harmonic spectrum has also been studied in detail, and its correlation with the filamentation of the laser beam has been established. Starting almost with a monochromatic component of laser beam propagation, the second harmonic spectrum becomes more complicated, and broadened when the laser beam propagates further, and filamentation takes place. For the typical laser beam and plasma parameters: laser beam with wave length of 1064 nm, power flux of 1018 W/cm2, and plasma with temperature 1 KeV, we found that the conversion efficiency equals about (E2/E0) = 8 × 10−3, and the spectrum is quite broad, which depends upon the laser beam propagation distance. The results (specifically, the second harmonic spectral feature) presented here may be used for the diagnostics of laser produced plasmas.
The high energy loss of heavy ions in matter as well as the small angular scattering makes heavy ion beams an excellent tool to produce almost cylindrical and homogeneously excited volumes in matter. This aspect can be used to pump short wavelength lasers. For the first time, a beam of heavy ions was used to pump a short wavelength gas laser in an experiment performed at the GSI ion accelerator facility in December 2005. In this experiment, the well-known KrF* excimer laser was pumped with an intense uranium beam. Pulses of an uranium beam compressed down to 110 ns (full width at half maximum) with initial particle energy of 250 MeV per nucleon were stopped inside a gas laser cell. A mixture of an excimer laser premix gas (95.5%Kr + 0.5%F2) and a buffer gas (Ar) in different proportions was used as the laser gas. The maximum beam intensity reached in the experiment was 2.5 × 109 particles per pulse, which resulted in 34 J/g specific energy deposited in the laser gas. The laser effect on the transition at λ = 248 nm has been successfully demonstrated by various independent methods. There, the laser threshold was reached with a beam intensity of 1.2 × 109 particles per pulse, and the energy of the laser pulse of about 2 mJ was measured for an ion beam intensity of 2 × 109 particles per pulse. As a next step, it is planned to reduce the laser wavelength down to the vacuum ultraviolet spectral region, and to proceed to the excimer lasers of the pure rare gases. The perspectives for such experiments are discussed and the detailed estimations for Xe and Kr cases are given. We believe that the use of heavy ion beams as a pumping source may lead to new pumping schemes on the higher lying level transitions and considerably shorter wavelengths, which rely on the high cross sections for multiple ionization of the target species.
In order to develop a high repetition rate X-ray lasers, the
longitudinal-pumped transient collisional excitation (TCE) X-ray laser is
one of the most effective pumping schemes. The high directive Ni-like Mo
18.9 nm soft X-ray laser pumped by modest laser energy has already been
demonstrated by using the tabletop size Ti:sapphire/Nd:glass laser
system that delivering energy of 150 mJ in 475 fs at the center wavelength
of 1054 nm. The total energy in the pre-pulse and the main pulse was 150
mJ, which will make possible multi-hertz operation. To pursue the high
repetition rate of the laser-driven TCE X-ray laser, we have designed a
new 20 TW Ti:Sapphire laser system (600 mJ, 30 fs, 10 Hz). Special
attention was paid to improve the contrast ratio, control of pulse shape
as well as phase by an acoustic optic programmable dispersive filter
(AOPDF) and 1 kHz preamplifier. Preliminary data have shown good laser
characteristics. As the preliminary experiments, we have investigated high
order harmonics generation from low-density laser plasma by using the
solid target irradiated by a femtosecond laser pulse. The highest order
was the 51st. harmonic at wavelength of 15.61 nm.
Interaction phenomena of intense ion and laser radiation with matter have a large range of application in different fields of science, from basic research of plasma properties to application in energy science. The hot dense plasma of our neighbouring star the Sun provides a deep insight into the physics of fusion, the properties of matter at high energy density, and is moreover an excellent laboratory for astroparticle physics. As such the Sun's interior plasma can even be used to probe the existence of novel particles and dark matter candidates. We present an overview on recent results and developments of dense plasma physics addressed with heavy ion and laser beams combined with accelerator and nuclear physics technology.
Experiments using high-energy/high-power lasers have being pursued for almost a decade at GSI. In the regime of ultra-intense lasers, the PHELIX (Petawatt High-Energy Laser for heavy-Ion experiments) system has reached the 20 TW level and first successful experiments have been done. In addition to the experiments on heavy-ion energy loss in laser produced plasmas, our research will focus on laser-assisted particle acceleration and the use of high-energy petawatt lasers (HEPW) for the diagnostics of dense plasmas which has raised great interest in the international community. The plasma physics group at GSI, based on experiments in France, the UK and the U.S., has contributed significantly to this field of research in recent years. Now, with the upcoming commissioning of different power levels of PHELIX our experimental activities can be performed at GSI. Due to the funding of a virtual institute by the Helmholtz Association, the opportunities for new experiments at GSI have grown significantly. The paper will give an overview of recent experimental results, show the link to the future GSI experimental program (including FAIR) and present the experiments that will be done at GSI for the years to come.
High intensity particle beams from accelerators induce high energy density states in bulk matter. Due to the specific nature of the ion-matter interaction a volume of matter is heated uniformly with low gradients of temperature and pressure in the initial phase, depending on the pulse structure of the beam with respect to space and time. We present an overview on recent results and developments of beam plasma, and beam matter interaction experiments with heavy ion and laser beams (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
During the past decade, substantial progress has been made in the technology of highly focused, strongly bunched intense beams of energetic ions. These developments have lead to a new concept of studying high energy density (HED) states in matter by isochoric and uniform heating of samples of matter by these intense particle beams. Existing accelerator facilities and those planned for the future, make the Gesellschaft für Schwerionenforschung (GSI), Darmstadt, a unique laboratory worldwide to carry out novel studies in this important field of research. Over the past few years, extensive theoretical work has been carried out to design novel experiments to study the thermophysical properties of HED matter. An overview of this work is presented in this paper highlighting the salient features of this new approach.
High energy heavy ions were generated in laser produced plasma at moderate laser energy, with a large focal spot size of 0.5 mm diameter. The laser beam was provided by the 10 GW GSI-NHELIX laser systems, and the ions were observed spectroscopically in status nascendi with high spatial and spectral resolution. Due to the focal geometry, plasma jet was formed, containing high energy heavy ions. The velocity distribution was measured via an observation of Doppler shifted characteristic transition lines. The observed energy of up to 3 MeV of F-ions deviates by an order of magnitude from the well-known Gitomer ~Gitomer et al., 1986! scaling, and agrees with the higher energies of relativistic self focusing.
Since their discovery, laser accelerated ion beams have been the
subject of great interest. The ion beam peak power and beam emittance is
unmatched by any conventionally accelerated ion beam. Due to the unique
quality, a wealth of applications has been proposed, and the first
experiments confirmed their prospects. Laser ion acceleration is strongly
linked to the generation and transport of hot electrons by the interaction
of ultra-intense laser light with matter. Comparing ion acceleration
experiments at laser systems with different beam parameters and using
targets of varying thickness, material and temperature, some insight on
the underlying physics can be obtained. The paper will present
experimental results obtained at different laser systems, first beam
quality measurement on laser accelerated heavy ions, and ion beam source
size measurements at different laser parameters. Using structured targets,
we compare information obtained from micro patterned ion beams about the
accelerating electron sheath, and the influence of magnetic fields on the
electron transport inside conducting targets.
The Vulcan Nd:glass laser at the Central Laser Facility (CLF) is a petawatt (1015 Watts) interaction facility, designed to deliver irradiance on target of 1021W.cm−2 for the UK and international user community. The facility came online to users in 2002 and considerable experience has been gained operating Vulcan in this mode. The facility delivers a wide-ranging experimental program in fundamental physics and advanced applications. This includes the interaction of ultrahigh intensity light with matter, fast ignition fusion research, photon induced nuclear reactions, electron and ion acceleration by light waves, and the exploration of the exotic world of plasma physics dominated by relativity. We report on the first year's operation of the facility and the highlights of the experimental campaigns.
The Gesellschaft für Schwerionenforschung (GSI) Darmstadt has been approved to build a new powerful facility named FAIR (Facility for Antiprotons and Ion Research) which involves the construction of a new synchrotron ring SIS100. In this paper, we will report on the results of a parameter study that has been carried out to estimate the minimum pulse lengths and the maximum peak powers achievable, using bunch rotation RF gymnastic-including nonlinearities of the RF gap voltage in SIS100, using a longitudinal dynamics particle in cell (PIC) code, ESME. These calculations have shown that a pulse length of the order of 20 ns may be possible when no prebunching is performed while the pulse length gradually increases with the prebunching voltage. Three different cases, including 0.4 GeV/u, 1 GeV/u, and 2.7 GeV/u are considered for the particle energy. The worst case is for the kinetic energy of 0.4 GeV/u which leads to a pulse length of about 100 ns for a prebunching voltage of 100 kV (RF amplitude). The peak power was found to have a maximum, however, at 0.52 × 1012 ions. Availability of such a powerful beam will make it possible to study the properties of high-energy-density (HED) matter in a parameter range that is very difficult to access by other means. These studies involve irradiation of high density targets by the ion beam for which optimization of the target heating is the key problem. The temperature to which a target can be heated depends on the power that is deposited in the material by the projectile ions. The optimization of the power, however, depends on the interplay of various parameters including beam intensity, beam spot area, and duration of the ion bunch. The purpose of this paper is to determine a set of the above parameters that would lead to an optimized target heating by the future SIS100 beam.
Borneis, S Becker-de-Moos, B Kluge, HJ Kuhl, T Marx, D Nickles, PV Neumayer, P Sandner, W Seelig, W
A new LabVIEW-based control system for the ISOLTRAP facility at ISOLDE/CERN has been implemented by using the Control System (CS) framework which has been developed by DVEE/GSI during the last two years. CS is an object-oriented, multi-threaded, event-driven framework with Supervisory Control and Data Acquisition (SCADA) functionality. It allows one to implement distributed control systems by adding experiment specific add-ons. This paper gives an overview on the CS framework, describes the requirements for ISOLTRAP and reports on the implementation of the new control system.
We have demonstrated the amplification and subsequent recompression of optical chirped pulses. A system which produces 1.06 μm laser pulses with pulse widths of 2 ps and energies at the millijoule level is presented.
A transient collisionally excited X-ray laser has been put into operation using the front end of the PHELIX laser system as a pump laser. Strong lasing at 22 nm has been observed in nickel-like zirconium.
We have developed a hybrid Ti:sapphire-Nd:glass laser system that produces more than 1500 TW (1.5 PW) of peak power. The system produces 660 J of power in a compressed 440+/-20 fs pulse by use of 94-cm master diffraction gratings. Focusing to an irradiance of >7x10(20) W/cm (2) is achieved by use of a Cassegrainian focusing system employing a plasma mirror.
We describe the design and operation of an all-reflective on-axis
pulse stretcher (with only four simple elements) that has achieved
stretching ratios of over 40000. The design is insensitive to alignment
errors and is simple to align. Optical aberrations in the system have an
effect on the fourth-order phase term, but this can be used to
compensate for material dispersion, resulting in a quintic-phase-limited
chirped-pulse-amplification system
Facility for Antiproton and Ion Research, Concep-tual Design Report
- Fair ~2003 ! Hernandez-Gomez
- C Collier
- J Hawkes
- S ~
FAIR ~2003!. Facility for Antiproton and Ion Research, Concep-tual Design Report. Hernandez-Gomez, C., Collier, J. & Hawkes, S. ~1998!. CLF Annual Report 1997098, 153.