D. Hitz

Oak Ridge National Laboratory, Oak Ridge, FL, United States

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Publications (113)150.87 Total impact

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    ABSTRACT: iThemba Laboratory for Accelerator Based Science (iThemba LABS) is a multi-disciplinary accelerator facility. One of its main activities is the operation of a separated-sector cyclotron with a K-value of 200, which provides beams of various ion species. These beams are used for fundamental nuclear physics research in the intermediate energy region, radioisotope production, and medical physics applications. Due to the requirements of nuclear physics for new ion species and higher energies, the decision was made to install a copy of the so-called Grenoble test source (GTS) at iThemba LABS. In this paper, we will report on the experimental setup and the first results obtained with the GTS2 at iThemba LABS.
    The Review of scientific instruments 02/2012; 83(2):02A323. · 1.52 Impact Factor
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    ABSTRACT: In this paper, we present the first absolute measurements for photoionization of multiply charged oxygen ions: O2+ and O3+ in the ground state and in several metastable states, as well as relative data for O4+. Multiconfiguration Dirac-Fock and relativistic R-matrix calculations were performed and are tested here by comparison with experimental results. Our experimental and new theoretical results are also compared with the earlier theoretical data obtained in the R-matrix approximation to calculate photoionization cross sections over part of the isonuclear series of multiply charged oxygen ions.
    The Astrophysical Journal Supplement Series 12/2008; 148(2):583. · 16.24 Impact Factor
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    ABSTRACT: The design of each component of the Multipurpose Superconducting ECR Ion Source (MS-ECRIS) has been completed and some items are ready. The magnets and the cryostat are under construction at ACCEL and the commissioning is scheduled for March 2007. The mechanical have been optimized and their construction is under way; the microwave system is under refurbishment and the 65kV power supply is available and upgraded for afterglow operations. Pumping and extraction system were adapted to the EIS testbench of GSI Darmstadt. The description of each part will be given in the paper along with a schedule of the forthcoming development and experiments.
    High Energy Physics and Nuclear Physics -Beijing- 07/2007; 31(supp.1):13-17. · 0.23 Impact Factor
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    ABSTRACT: In the collision of highly charged ions on atoms or simple molecules, one electron (or more) may be transferred to the projectile. It is observed that in the low velocity range (ν < ν0), the one electron charge exchange cross-section is quasi energy independent at least in the energy range 2q-10q keV when q ≥ 4. It is shown that a scaling law may be deduced from a series of measured values obtained with Cq+, Nq+, Oq+, Arq+, Xeq+, some of them up to completely stripped (C, N, O; Ar up to q = 16). Since the collision may be described along quasi-molecular approaches, it is known that the projectile after capture is left in excited states. An attempt is made to observe part of the radiative decay in the case of the capture of one electron by completely stripped C, O and Ne ions which are thus left hydrogenic and radiate in the soft X-ray range. The X-ray emission cross section is shown to be large and may be utilized to calculate the excitation cross-section for a given level.
    Physica Scripta 02/2007; 1983(T3):63. · 1.03 Impact Factor
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    ABSTRACT: The GTS-LHC ion source, designed and build by CEA Grenoble, was installed and commissioned at CERN in 2005. Since than the source has delivered oxygen and lead ion beams (O4+ and Pb27+ from the source, Pb54+ from the linac) for the commissioning of the Low Energy Ion Ring (LEIR). Results of this operation and attempts to improve the source performance and reliability, and the linac performance will be presented in this paper.
    01/2007;
  • D Hitz, R Berreby, M Druetta
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    ABSTRACT: Spectroscopic investigation in the 10–80 nm spectral range of the plasma generated by an Electron Cyclotron Resonance (E.C.R.) ion source has been realized. The results are based on oxygen. O V intensity line ratio measurements inside the plasma are investigated as a function of the RF power. Results are correlated with the extracted O4+ current. The electronic density and temperature have been derived from the computed results of Kato et al. Finally, first determination of ionic densities and lifetimes have been performed.
    Physica Scripta 11/2006; 1999(T80B):511. · 1.03 Impact Factor
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    ABSTRACT: We present absolute measurements for photoionisation of multiply-charged ions N2+ and O3+ in the ground and metastable states. Multiconfiguration Dirac Fock calculations were performed for N2+ and are tested here by comparison with experimental results. Our experimental and theoretical results are also compared to the theoretical data available in the Opacity Project data base.
    Physica Scripta 07/2006; 2004(T110):57. · 1.03 Impact Factor
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    Review of Scientific Instruments 01/2006; · 1.60 Impact Factor
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    ABSTRACT: A new 250 kV high-voltage platform has been installed at the ORNL multicharged ion research facility (MIRF) to extend the energy range of multicharged ions available for experimental investigations of their collisional interactions with electrons, atoms, molecules and solid surfaces. For the production of the multiply charged ions, a new all-permanent magnet electron cyclotron resonance (ECR) ion source, designed and fabricated at CEA/Grenoble, is being used. After a brief summary of the project background and the expanded research program made possible upon its completion, design details of the new platform, associated beam transport and control system are presented, together with information on the design and performance of the new ion source.
    Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms 01/2006; · 1.27 Impact Factor
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    ABSTRACT: The ECLISSE experiment has been carried out by coupling a Laser Ion Source (based on a Nd:YAG laser (0.9 J / 9 ns, laser power densities <1011 W/cm2) to the SERSE superconducting ECR ion source. Cw beams of highly charged ions from metal samples without the use of ovens or sputtering technics were obtained in a variety of experimental conditions. The maximum charge states obtained from the ECRIS were 38+ for Ta and 41+ for Au. The peak current was obtained for 25+ and 29+ respectively and it was in the order of some tens of {mu}A. In this work the analysis of some preliminary results obtained in afterglow mode will be also presented. We employed microwave pulse (length 4 msec) and laser pulse (length 9 nsec) with the same frequency (30 Hz) and variable relative phase. For appropriate phase values, a current enhancement of about one order of magnitude was observed.
    Plasma Processes and Polymers 07/2005; 2(6):458 - 463. · 3.73 Impact Factor
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    ABSTRACT: A new 250 kV high voltage platform has been installed at the ORNL Multicharged Ion Research Facility (MIRF) to extend the energy range of multicharged ions available for experimental investigations of their collisional interactions with electrons, atoms, molecules, and solid surfaces. A new all-permanent magnet Electron Cyclotron Resonance (ECR) ion source, designed and fabricated at CEA-Grenoble, was installed on the platform to produce the ion beams of interest. Design details of the new platform and beamlines, and their associated beam transport, are presented below.
    Particle Accelerator Conference, 2005. PAC 2005. Proceedings of the; 06/2005
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    ABSTRACT: A new ion source to be installed on a compact high voltage platform is under study. The purpose of this machine is to deliver very high charge states, which requires long ion lifetimes and then a large plasma volume. On the other hand, to deliver intense beams, the highest frequency compatible with the magnetic confinement has been chosen. Due to the room available for this source, the magnetic system is chosen hybrid: radial field is created by permanent magnets, while axial field is produced by 4K superconducting coils placed in a cryostat filled with LHe. This article gives the major parameters of this ion source, with a special emphasis on the magnetic system and its cryogenic features.
    AIP Conference Proceedings. 03/2005; 749(1).
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    ABSTRACT: With the development of Electron Cyclotron Resonance Ion Source (ECRIS), very high performance ECRIS nowadays have been set up one by one around the world, such as the GTS in Grenoble, SERSE in Catania, LECR3 in Lanzhou and etc, which can produce very intense Multiply Charged Ion (MCI) beam. But till now, the study of the extracted MCI beam from an ECRIS remains open. In this article, we present a theoretical and experimental study of the extracted MCI beam. In the theoretical part, the influences of the extraction system on the extracted ion beam quality are mainly analyzed. The aspects that have influences on the extracted ion beam quality have been analyzed. With the instruction of the analysis, the PBGUNS code is used to simulate the influences of some important aspects concerning the extraction system. The influences of the extraction system geometry design, magnetic field, and the space charge effect will be detailedly presented in this article. In the experimental part, with an Electric-Sweep Scanner (ESS) emittance detection system, the influences on the extracted ion beam emittance of some typical parameters of ECRIS have been researched, such as the injected RF power, the RF frequency, the magnetic field and etc. The obtained results and the corresponding explanations are presented. Some of the results are well in accord with some empirical laws, but some other results seem to be disputed.
    AIP Conference Proceedings. 03/2005; 749(1).
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    ABSTRACT: The ion injector chain for the LHC has to be adapted and modified to reach the design beam parameters. Up to now an ECR4 delivered the ion beam for the SPS fixed target physics programme. This source will be replaced by a higher intensity source to produce the Pb27+ ion current required to fill the Low Energy Ion Ring (LEIR). The new ion source will be based on the Grenoble Test Source which was itself based on empirical scaling laws derived from the Framework 5 “Innovative ECRIS” collaboration. This paper will describe the design principle, the commissioning timetable and the present status of the source development.
    03/2005;
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    ABSTRACT: A new high voltage platform has been installed at the ORNL Multicharged Ion Research Facility (MIRF) to extend the energy range of multicharged ions available for experiments studying their collisional interactions with electrons, atoms, molecules, and solid surfaces. For the production of the multiply charged ions, a new all‐permanent magnet ECRIS has been designed and fabricated at CEA/Grenoble. After a brief overview of the basic features of the new platform, and associated beam transporta detailed description of the new ion source design and performance is provided, together with some typical Ar, Xe, and O beam intensities obtained during source commissioning prior to shipment to ORNL. © 2005 American Institute of Physics
    AIP Conference Proceedings. 03/2005; 749(1):123-126.
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    ABSTRACT: The experiment concerning the ECLISSE method (ECR ion source coupled to a laser ion source for charge state enhancement) has been carried out by coupling a laser ion source (LIS) to the superconducting electron cyclotron resonance source (SERSE) electron cyclotron resonance (ECR) ion source with the goal to obtain intense beams of highly charged ions (cw or pulsed mode) from metal samples, especially from refractory elements. The coupling efficiency of the ion beam produced by the LIS with the ECR plasma was remarkable and the measured beam intensities were quite high. The maximum charge states, obtained with a good reproducibility, were 38+ for Ta and 41+ for Au. The highest current was obtained for 25+ and 28+ for Ta and Au ions, respectively, and it was in both cases of the order of some tens of microampere, i.e., higher than the current obtained from SERSE with other methods (i.e., evaporation and sputtering). The ion beam stability and reproducibility were both acceptable. The possibility to get a further enhancement of the available charge states was limited by charge exchange processes connected with the target ablation. The main features of the LNS facility based on a Nd:YAG (yag, yttrium aluminum garnet) laser (0.9 J∕9 ns, laser power densities <5×1010 W∕cm2) and on the SERSE superconducting ECRIS working in single frequency mode (18 GHz) will be shown in the following. The analysis of the results and the way to get rid of the existing limits will be also presented and discussed.
    Journal of Applied Physics 08/2004; 96(5):2961-2968. · 2.21 Impact Factor
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    ABSTRACT: The performance of the electron cyclotron resonance ion source (ECRIS) increases proportionally to the microwave frequency squared. This behavior encourages the use of higher microwave frequencies. However, a higher frequency would require a stronger magnetic field for the efficient operation of ECRIS. A rather complicated magnetic field configuration results from the combination of solenoids for the axial confinement and a multipolar radial field usually provided by permanent magnets. These fields produce the so-called B-minimum structure which is required for a stable and efficient operation of ECRIS. The highest multipole field achieved so far in an ECR ion source by using permanent magnets is about 1.3 T. This makes the efficient operation at a microwave frequency of about 18 GHz possible. We introduce here a new approach to further increase the magnetic multipole field provided by permanent magnets. According to our two-dimensional (2D) simulations, a remarkable improvement in the radial magnetic field of the multipole can be achieved. The idea was tested using a simple construction in the plasma chamber of the JYFL 6.4 GHz ECRIS. The multipole field increased from 0.37 to 0.5 T while the solenoids for the axial magnetic field were excited. This result is consistent with our 2D simulations. Based on our simulations and the simple test with the JYFL 6.4 GHz ECRIS, we believe that a multipole field value of 2 T is feasible in ECRIS while still using permanent magnets. © 2004 American Institute of Physics.
    Review of Scientific Instruments 05/2004; 75(5):1479-1481. · 1.60 Impact Factor
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    ABSTRACT: Electron cyclotron resonance (ECR) ion sources are scientific instruments particularly useful for physics: they are extensively used in atomic, nuclear, and high energy physics, for the production of multicharged beams. Moreover, these sources are also of fundamental interest for plasma physics, because of the very particular properties of the ECR plasma. This article describes the state of the art on the physics of the ECR plasma related to multiply charged ion sources. In Sec. I, we describe the general aspects of ECR ion sources. Physics related to the electrons is presented in Sec. II: we discuss there the problems of heating and confinement. In Sec. III, the problem of ion production and confinement is presented. A numerical code is presented, and some particular and important effects, specific to ECR ion sources, are shown in Sec. IV. Eventually, in Sec. V, technological aspects of ECR are presented and different types of sources are shown. © 2004 American Institute of Physics.
    Review of Scientific Instruments 05/2004; 75(5):1381-1388. · 1.60 Impact Factor
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    ABSTRACT: Grenoble Test Source (GTS) is a room temperature electron cyclotron resonance ion source whose purpose is to deepen the knowledge of this type of device. GTS was designed according to magnetic scaling laws determined with the SERSE source [Hitz et al., Rev. Sci. Instrum. 73, 509 (2002); Gammino et al., ibid. 72, 4090 (2001)] while keeping enough flexibility in terms of magnetic confinement and rf heating to determine best conditions for the production of intense beams of any charge state. First results were presented 1 year ago [Hitz et al., 8th European Particle Accelerator Conference, 2002; 15th International Workshop on ECR Ion Sources, 2002]. Since then, some improvements have been performed mostly in the magnetic confinement, beam extraction and analysis. Updated ion beam intensities are presented: e.g., 0.5 mA of Ar11+ at 18 GHz, 20 μA of Ar16+ and 1.8 μA of Ar17+ when GTS is operated at 14.5 GHz. On the other hand, charge coupled device imagers have been installed to diagnose and monitor the ion beam and some beam images are shown. © 2004 American Institute of Physics.
    Review of Scientific Instruments 05/2004; 75(5):1403-1406. · 1.60 Impact Factor
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    ABSTRACT: In order to predict the performances of electron cyclotron resonance ion source (ECRIS), it is necessary to perfectly model the different parts of these sources: (i) magnetic configuration; (ii) plasma characteristics; (iii) extraction system. The magnetic configuration is easily calculated via commercial codes; different codes also simulate the ion extraction, either in two dimension, or even in three dimension (to take into account the shape of the plasma at the extraction influenced by the hexapole). However the characteristics of the plasma are not always mastered. This article describes the self-consistent modeling of ECRIS: we have developed a code which takes into account the most important construction parameters: the size of the plasma (length, diameter), the mirror ratio and axial magnetic profile, whether a biased probe is installed or not. These input parameters are used to feed a self-consistent code, which calculates the characteristics of the plasma: electron density and energy, charge state distribution, plasma potential. The code is briefly described, and some of its most interesting results are presented. Comparisons are made between the calculations and the results obtained experimentally. © 2004 American Institute of Physics.
    Review of Scientific Instruments 05/2004; 75(5):1463-1466. · 1.60 Impact Factor

Publication Stats

706 Citations
150.87 Total Impact Points

Institutions

  • 2005
    • Oak Ridge National Laboratory
      • Physics Division
      Oak Ridge, FL, United States
  • 2004
    • University of Jyväskylä
      • Department of Physics
      Jyväskylä, Western Finland, Finland
  • 1987–2004
    • Cea Leti
      Grenoble, Rhône-Alpes, France
  • 2002
    • Universität Stuttgart
      • Institute of Plasma Research
      Stuttgart, Baden-Wuerttemberg, Germany
  • 2000
    • Université Jean Monnet
      Saint-Étienne, Rhône-Alpes, France
  • 1998
    • Université Paris-Sud 11
      Orsay, Île-de-France, France
    • Paul Sabatier University - Toulouse III
      • Laboratoire des Collisions, Agrégats et Réactivité - UMR 5589 - LCAR
      Tolosa de Llenguadoc, Midi-Pyrénées, France