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Ogata, D.

Paper Title Page
THPAS004 Bunching and Focusing of an Intense Ion Beam for Target Heating Experiments 3516
 
  • J. E. Coleman, P. K. Roy, P. A. Seidl
    LBNL, Berkeley, California
  • E. P. Gilson, A. B. Sefkow
    PPPL, Princeton, New Jersey
  • D. Ogata
    UCB, Berkeley, California
  • D. R. Welch
    Voss Scientific, Albuquerque, New Mexico
  
  Funding: This work was supported by the U. S. D. O.E. under DE-AC02-05H11231 and DE-AC02-76CH3073 for HIFS-VNL

Future warm dense matter experiments with space-charge dominated ion beams require simultaneous longitudinal bunching and transverse focusing. The challenge is to longitudinally bunch the beam two orders of magnitude to a pulse length shorter than the target disassembly time and focus the beam transversely to a sub-mm focal spot. An experiment to simultaneously focus a singly charged potassium ion beam has been carried out at LBNL. The space charge of the beam must be neutralized so only emittance limits the simultaneous focusing. An induction bunching module provides a head-to-tail velocity ramp upstream of a plasma filled drift section. Tuning the initial beam envelope to compensate for the defocusing of the bunching module enables simultaneous focusing. A comparison of experimental and calculated results are presented, including the transverse distribution and the longitudinal phase-space of the beam.

 
THPAS006 A Solenoid Final Focusing System with Plasma Neutralization for Target Heating Experiments 3519
 
  • P. K. Roy, F. M. Bieniosek, J. E. Coleman, J.-Y. Jung, M. Leitner, B. G. Logan, P. A. Seidl, W. L. Waldron
    LBNL, Berkeley, California
  • J. J. Barnard, A. W. Molvik
    LLNL, Livermore, California
  • R. C. Davidson, P. Efthimion, E. P. Gilson, A. B. Sefkow
    PPPL, Princeton, New Jersey
  • J. A. Duersch, D. Ogata
    UCB, Berkeley, California
  • D. R. Welch
    Voss Scientific, Albuquerque, New Mexico
  
  Intense bunches of low-energy heavy ions have been suggested as means to heat targets to the warm dense matter regime (0.1 to 10 eV). In order to achieve the required intensity on target (~1 eV heating), a beam spot radius of approximately 0.5 mm, and pulse duration of 2 ns is required with an energy deposition of approximately 1 J/cm2. This translates to a peak beam current of 8A for ~0.4 MeV K+ ions. To increase the beam intensity on target, a plasma-filled high-field solenoid is being studied as a means to reduce the beam spot size from several mm to the sub-mm range. We are building a prototype experiment to demonstrate the required beam dynamics. The magnetic field of the pulsed solenoid is 5 to 8 T. Challenges include suitable injection of the plasma into the solenoid so that the plasma density near the focus is sufficiently high to maintain space-charge neutralization of the ion beam pulse. Initial experimental results for a peak current of ~1A will be presented.

This work was supported by the Office of Fusion Energy Sciences, of the U. S. Department of Energy under Contract No. DE-AC02-05CH11231, W-7405-Eng-48, DE-AC02-76CH3073 for HIFS-VNL.