A   B   C   D   E   F   G   H   I   J   K   L   M   N   O   P   Q   R   S   T   U   V   W   X   Y   Z  

Logan, B. G.

Paper Title Page
MOOBC02 Experiments in Warm Dense Matter using an Ion Beam Driver 140
  • F. M. Bieniosek, M. Leitner, B. G. Logan, R. More, P. N. Ni, P. K. Roy
    LBNL, Berkeley, California
  • J. J. Barnard, M. Kireeff Covo, A. W. Molvik
    LLNL, Livermore, California
  • L. Grisham
    PPPL, Princeton, New Jersey
  • H. Yoneda
    University of electro-communications, Tokyo
  Funding: Work performed under the auspices of the U. S. Dept. of Energy by LBNL, LLNL, and PPPL under Contracts No. W-7405-Eng-48, DE-AC02-05CH11231, and DE-AC02-76CH3073.

We describe near term heavy-ion beam-driven warm dense matter (WDM) experiments. Initial experiments are at low beam velocity, below the Bragg peak, increasing toward the Bragg peak in subsequent versions of the accelerator. The WDM conditions are envisioned to be achieved by combined longitudinal and transverse neutralized drift compression to provide a hot spot on the target with a beam spot size of about 1 mm, and pulse length about 1-2 ns. The range of the beams in solid matter targets is about 1 micron, which can be lengthened by using porous targets at reduced density. Initial candidate experiments include an experiment to study transient darkening in the WDM regime; and a thin target dE/dx experiment to study beam energy and charge state distribution in a heated target. Further experiments will explore target temperature and other properties such as electrical conductivity to investigate phase transitions and the critical point.

slides icon Slides  
TUXAB01 Absolute Measurement of Electron Cloud Density 754
  • M. Kireeff Covo, R. H. Cohen, A. Friedman, A. W. Molvik
    LLNL, Livermore, California
  • D. Baca, F. M. Bieniosek, B. G. Logan, P. A. Seidl, J.-L. Vay
    LBNL, Berkeley, California
  • J. L. Vujic
    UCB, Berkeley, California
  Funding: This work was supported by the Director, Office of Science, Office of Fusion Energy Sciences, of the U. S. Department of Energy, LLNL and LBNL, under contracts No. W-7405-Eng-48 and DE-AC02-05CH11231.

Beam interaction with background gas and walls produces ubiquitous clouds of stray electrons that frequently limit the performance of particle accelerator and storage rings. Counterintuitively we obtained the electron cloud accumulation by measuring the expelled ions that are originated from the beam-background gas interaction, rather than by measuring electrons that reach the walls. The kinetic ion energy measured with a retarding field analyzer (RFA) maps the depressed beam space-charge potential and provides the dynamic electron cloud density. Clearing electrode current measurements give the static electron cloud background that complements and corroborates with the RFA measurements, providing an absolute measurement of electron cloud density during a 5 us duration beam pulse in a drift region of the magnetic transport section of the High-Current Experiment (HCX) at LBNL.*

* M. Kireeff Covo, A. W. Molvik, A. Friedman, J.-L. Vay, P. A. Seidl, G. Logan, D. Baca, and J. L. Vujic, Phys. Rev. Lett. 97, 054801 (2006).

slides icon Slides  
TUXC01 Status of DARHT 2nd Axis Accelerator at the Los Alamos National Laboratory 831
  • R. D. Scarpetti, J. Barraza, C. Ekdahl, E. Jacquez, S. Nath, K. Nielsen, G. J. Seitz
    LANL, Los Alamos, New Mexico
  • F. M. Bieniosek, B. G. Logan
    LBNL, Berkeley, California
  • G. J. Caporaso, Y.-J. Chen
    LLNL, Livermore, California
  This presentation will provide a status report on the 2kA, 17MeV, 2-microsecond Dual-Axis Radiographic Hydrotest electron beam accelerator at Los Alamos National Laboratory, and will cover results from the cell refurbishment effort, commissioning experiments on beam transport and stability through the accelerator, and experiments exercising the beam chopper.  
slides icon Slides  
WEOCC02 Overview of warm-dense-matter experiments with intense heavy ion beams at GSI-Darmstadt 2038
  • P. N. Ni, F. M. Bieniosek, M. Leitner, B. G. Logan, R. More, P. K. Roy
    LBNL, Berkeley, California
  • J. J. Barnard
    LLNL, Livermore, California
  • A. Fernengel, A. Menzel
    TU Darmstadt, Darmstadt
  • A. Fertman, A. Golubev, B. Y. Sharkov, I. Turtikov
    ITEP, Moscow
  • D. Hoffmann, A. Hug, N. A. Tahir, A. Udrea, D. Varentsov
    GSI, Darmstadt
  • M. Kulish, D. Nikolaev, A. Ternovoy
    IPCP, Chernogolovka, Moscow region
  Recently, a series of high energy density (HED) physics experiments with heavy ion beams have been carried out at the GSI heavy ion accelerator. The ion beam spot of heating uranium beam size of about 1 mm, pulse length about 120 ns and intensity 109 particles/bunch. In these experiments, metallic solid and porous targets of macroscopic volumes were heated by intense heavy ion beams uniformly and quasi-isochorically, and temperature, pressure and expansion velocity were measured during the heating and cooling of the sample using a fast multi-channel radiation pyrometer, laser Doppler interferometer (VISAR), Michelson displacement interferometer and streak-camera-based-backlighting system. In the performed experiments target temperatures varying from 1'000 K to 12'000 K and pressure in kbar range were measured. Expansion velocities up to 2600 m/s have been registered for lead and up to 1700 m/s for tungsten targets.  
slides icon Slides  
THPAS082 Meter-Long Plasma Source for Heavy Ion Beam Space Charge Neutralization 3672
  • P. Efthimion, R. C. Davidson, E. P. Gilson, L. Grisham
    PPPL, Princeton, New Jersey
  • B. G. Logan, P. A. Seidl, W. L. Waldron, S. Yu
    LBNL, Berkeley, California
  Funding: Research supported by the U. S. Department of Energy.

Plasmas are sources of electrons for charge neutralizing ion beams to allow them to focus to small spot sizes and compress their axial pulse length. Sources must operate at low pressures and without strong electric/magnetic fields. To produce meter-long plasmas, sources based on ferroelectric ceramics with large dielectric coefficients were developed. The sources use BaTiO3 ceramic to form plasma. The drift tube inner wall of the Neutralized Drift Compression Experiment (NDCX) is covered with ceramic and ~7 kV is applied across the wall of the ceramics. A 20-cm-long prototype source produced plasma densities of 5·1011 cm-3. It was integrated into the Neutralized Transport Experiment and successfully neutralized the K+ beam. A one-meter-long source comprised of five 20-cm-long sources has been tested and characterized, producing relatively uniform plasma over the length of the source in the 1·1010 cm-3 range. This source was integrated into NDCX for beam compression experiments. Experiments with this source yielded compression ratios ~80. Future work will consider longer and higher plasma density sources to support beam compression and high energy density experiments.

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.