No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
An Update of Target Fabrication Techniques for the Mass Production of Advanced Fast Ignition Cone Targets
Abstract
The United States and France are constructing multi-billion-dollar laser facilities to demonstrate inertial fusion as a potential source of energy for the future. These facilities aim to use the inertial confinement fusion scheme to demonstrate ignition on the 2010-2012 time-scale. The recently launched High Power Laser Energy Research facility (HiPER) project is a European initiative to offer a credible way to build upon this work and demonstrate the possibility of opening up inertial fusion energy as a commercial process for energy generation. These facilities pose huge engineering and scientific challenges not only in their design but also in the technical challenges of providing the targets that will contain the fuel required to run them. We review the current manufacturing techniques of the cone target component as well as the work toward mass production of this component.
... Large-scale facilities with high-power lasers (petawatt class lasers) need to operate at high-repetition rates to utilise the full potential of the lasers, which comes with many engineering challenges Spindloe et al., 2011). One such challenge is the requirement for positioning and orientating the fresh targets at the laser beam focus with an accuracy of a few micrometres at a rate of at least a few hertz Booth et al., 2014;Tolley & Spindloe, 2013;Spindloe et al., 2011). ...
... Large-scale facilities with high-power lasers (petawatt class lasers) need to operate at high-repetition rates to utilise the full potential of the lasers, which comes with many engineering challenges Spindloe et al., 2011). One such challenge is the requirement for positioning and orientating the fresh targets at the laser beam focus with an accuracy of a few micrometres at a rate of at least a few hertz Booth et al., 2014;Tolley & Spindloe, 2013;Spindloe et al., 2011). For example, clinically relevant experiments require several thousands of laser shots, which demand for an automated target positioning system. ...
... With the use of a six-axis hexapod, a specially designed target wheel, a microscope and a confocal chromatic displacement sensor, they achieved a target positioning accuracy of around 5 µm in all spatial dimensions at 0.5 Hz repetition rate; but this method represents a pre-calibrated compensation for target's positional deviations. Another method of automated target alignment (positioning and orientation) can be found in the form of an integrated target solution developed by the Central Laser Facility (CLF) Symes et al., 2014;Spindloe et al., 2011). The target solution of the CLF, known as the "High Accuracy Microtarget Supply" (HAMS) system, uses a number of identical targets manufactured with MEMS technology and delivers the targets to the laser focus within specifications at high speed (hertz level). ...
This paper presents a real-time position control solution for the targets used in the high-repetition rate laser operations of high-power laser facilities. The control system is designed based on an Abbe-compliant, in-process position measurement system of targets, employing a plane mirror interferometer and a five degree-of-freedom hybrid mechanism. An error model is developed to characterise the position feedback information of target for a high-repetition rate process to determine the effects of the non-collocation of the sensor’s measurement point and target on the control system’s performance – a challenge for the real-time position control of targets. Behaviour of the control system is investigated with the error model and experimental data. It is found that a controller’s position compensation scheme can be ineffective due to the erroneous position feedback as a result of the non-linear position information associated with the non-collocated measurement point and the actual target. To solve the problem, an angular compensation technique is proposed.
... Large-scale facilities with high-power lasers (petawatt class lasers) need to operate at high-repetition rates to utilise the full potential of the lasers, which comes with many engineering challenges Spindloe et al., 2011). One such challenge is the requirement for positioning and orientating the fresh targets at the laser beam focus with an accuracy of a few micrometres at a rate of at least a few hertz Spindloe et al., 2011;Symes et al., 2014;Tolley & Spindloe, 2013). ...
... Large-scale facilities with high-power lasers (petawatt class lasers) need to operate at high-repetition rates to utilise the full potential of the lasers, which comes with many engineering challenges Spindloe et al., 2011). One such challenge is the requirement for positioning and orientating the fresh targets at the laser beam focus with an accuracy of a few micrometres at a rate of at least a few hertz Spindloe et al., 2011;Symes et al., 2014;Tolley & Spindloe, 2013). For example, clinically relevant experiments require several thousands of laser shots, which demand for an automated target positioning system. ...
... form of an integrated target solution developed by the Central Laser Facility (CLF) Spindloe et al., 2011;Symes et al., 2014). The target solution of the CLF, known as the 'High Accuracy Microtarget Supply' (HAMS) system, uses a number of identical targets manufactured with MEMS technology and delivers the targets to the laser focus within specifications at high speed (hertz level). ...
... 4. Provide confidence to the customers and other stakeholders that the requirements for quality are being, or will be, achieved in the delivered product. 5. Provide confidence that the quality system requirements are fulfilled. ...
... It has high corrosion resistance though it oxidizes fairly easy when heated. It is unaffected by most acids, alkalis or other corrosive agents with the exception of aqua regia [5]. For our palladium plating a virtually neutral solution based on palladium diammino-nitride complex was employed. ...
... The fully automated machine with online tool wear measurement and tool change capabilities produced a number of mandrels ranging in number from single cone geometries to arrays of up to 25 targets. This technology was scaled to be able to produce 50 cone targets in a production run opening up the way to statistical studies during experimental campaigns 5 ...
... High-power lasers are used for advanced research activities in physics, chemistry and biology, for example, to accelerate subatomic particles to high energies, to study biochemical and biophysical processes, and for cuttingedge applications, such as fusion energy, radiation therapy and secondary source generation (X-rays, electrons, protons, neutron and ions) [1][2][3]. To utilise the full potential of high-power lasers, large-scale facilities need to operate at high-repetition rates, which presents many engineering challenges [3,4]. ...
... High-power lasers are used for advanced research activities in physics, chemistry and biology, for example, to accelerate subatomic particles to high energies, to study biochemical and biophysical processes, and for cuttingedge applications, such as fusion energy, radiation therapy and secondary source generation (X-rays, electrons, protons, neutron and ions) [1][2][3]. To utilise the full potential of high-power lasers, large-scale facilities need to operate at high-repetition rates, which presents many engineering challenges [3,4]. One such challenge is the positioning and aligning of a micro-scale target (or in short 'target') relative to the focus of the laser beam(s) with an accuracy of few micrometres -a fundamental requirement for a high-power laser-target interaction to ensure that targets are reproducibly accessible to the highest intensities available, that is in the region of the laser beam focus as determined by the Rayleigh range [5,6]. ...
The accuracy, repeatability and speed requirements of high-power laser operations demand the employment of five degree of freedom motion control solutions that are capable of positioning and orientating the target with respect to the laser(s)-target interaction point with high accuracy and precision. The combined serial and parallel kinematic (hybrid) mechanism reported in this paper is a suitable candidate for this purpose; however, a number of error sources can affect its performance. A kinematic model to analyse the errors causing the positional and orientational deviations of the target is described considering two rotational degrees of freedom of the hybrid mechanism. Strategies are outlined to simplify the error analysis and to determine the error parameters of the mechanism using the error model and an experimental technique. Keywords degree of freedom, hybrid mechanism, parallel kinematic structure, RPS mechanism, generalised error parameters, parasitic motion, error model.
A number of laser facilities coming online all over the world promise the capability of high-power laser experiments with shot repetition rates between 1 and 10 Hz. Target availability and technical issues related to the interaction environment could become a bottleneck for the exploitation of such facilities. In this paper, we report on target needs for three different classes of experiments: dynamic compression physics, electron transport and isochoric heating, and laser-driven particle and radiation sources. We also review some of the most challenging issues in target fabrication and high repetition rate operation. Finally, we discuss current target supply strategies and future perspectives to establish a sustainable target provision infrastructure for advanced laser facilities.
A neutron generator is developed using mm-diam spherical deuterated polystyrene targets on a rotating disk irradiated with an ultrahigh-intensity (>1018 W/cm2) diode-pumped laser. It consists of a rotating disk supplier, the targets, and a control system to irradiate the targets at 1.25 Hz. We adjusted the laser focus and position on the target to obtain the maximum neutron yield.
Microtargetry for high power lasers (HPLs) offers considerable challenges and opportunities at the cutting edge of the application of microtechnology production techniques. In this chaptermicrotarget production issues are discussed particularly in the context of the mass production of such components which has become one of the major challenges in delivering targets for High Power Laser (HPL) systems and will become essential in the near future as lasers move to application based systems. The challenges of microtarget placement are also discussed.
Ultrahigh intensity lasers can potentially be used in conjunction with conventional fusion lasers to ignite inertial confinement fusion (ICF) capsules with a total energy of a few tens of kilojoules of laser light, and can possibly lead to high gain with as little as 100 kJ. A scheme is proposed with three phases. First, a capsule is imploded as in the conventional approach to inertial fusion to assemble a high‐density fuel configuration. Second, a hole is bored through the capsule corona composed of ablated material, as the critical density is pushed close to the high‐density core of the capsule by the ponderomotive force associated with high‐intensity laser light. Finally, the fuel is ignited by suprathermal electrons, produced in the high‐intensity laser–plasma interactions, which then propagate from critical density to this high‐density core. This new scheme also drastically reduces the difficulty of the implosion, and thereby allows lower quality fabrication and less stringent beam quality and symmetry requirements from the implosion driver. The difficulty of the fusion scheme is transferred to the technological difficulty of producing the ultrahigh‐intensity laser and of transporting this energy to the fuel.
Hydrogen may be compressed to more than 10,000 times liquid density by an implosion system energized by a high energy laser. This scheme makes possible efficient thermonuclear burn of small pellets of heavy hydrogen isotopes, and makes feasible fusion power reactors using practical lasers.
Guided compression offers an attractive route to explore some of the physics issues of hot electron heating and transport in the fast ignition route to inertial confinement fusion, whilst avoiding the difficulties associated with establishing the stability of the channel formation pulse. X-ray images are presented that show that the guided foil remains hydrodynamically stable during the acceleration phase, which is confirmed by two-dimensional simulations. An integrated conical compression/fast electron heating experiment is presented that confirms that this approach deserves detailed study.
Modern high-power lasers can generate extreme states of matter that are relevant to astrophysics, equation-of-state studies and fusion energy research. Laser-driven implosions of spherical polymer shells have, for example, achieved an increase in density of 1,000 times relative to the solid state. These densities are large enough to enable controlled fusion, but to achieve energy gain a small volume of compressed fuel (known as the 'spark') must be heated to temperatures of about 108 K (corresponding to thermal energies in excess of 10 keV). In the conventional approach to controlled fusion, the spark is both produced and heated by accurately timed shock waves, but this process requires both precise implosion symmetry and a very large drive energy. In principle, these requirements can be significantly relaxed by performing the compression and fast heating separately; however, this 'fast ignitor' approach also suffers drawbacks, such as propagation losses and deflection of the ultra-intense laser pulse by the plasma surrounding the compressed fuel. Here we employ a new compression geometry that eliminates these problems; we combine production of compressed matter in a laser-driven implosion with picosecond-fast heating by a laser pulse timed to coincide with the peak compression. Our approach therefore permits efficient compression and heating to be carried out simultaneously, providing a route to efficient fusion energy production.