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in creator/contributor: "Barnard, JJ"

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Emittance growth from rotated quadrupoles in heavy ion accelerators

We derive a set of moment equations which incorporates linear quadrupolar focusing and space-charge defocusing, in the presence of rotational misalignments of the quadrupoles about the direction of beam propagation. Although the usual beam emittance measured relative to fixed transverse x and y coordinate axes is not constant, a conserved emittance-like quantity has been found. Implications for alignment tolerances in accelerators for heavy-ion inertial fusion are discussed.

Date: May 2, 1995

Creator: Barnard, J.J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Theory of longitudinal beam halo in RF linacs: I. core/test-particle formulation

For intense beams, the analysis of tenuous halo components of the particle distribution that surround the main core of the distribution can be challenging. So-called core/test particle models in which a test particle is evolved in the applied and space-charge forces of the beam core have been instrumental in understanding the structure and extent of transverse beam halo produced by resonant particle interactions with the oscillating space-charge forces of a mismatched beam core. Here we present… more

Date: May 1, 1997

Creator: Barnard, J.J. & Lund, S.M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Theory of longitudinal beam halo in RF linacs: II. envelope-particle resonances

Using the core/test-particle model described in a companion paper in these proceedings (``Theory of Longitudinal Halo in rf Linacs: I. Core/Test Particle Formulation,`` by J. J. Barnard and S. M. Lund), we analyze longitudinal beam halo produced by resonant self-field interactions in intense, ion-beam rf linacs. It is shown that particles moving in the presence of the space-charge forces of an oscillating, mismatched ellipsoidal beam bunch can be resonantly driven to large longitudinal amplitud… more

Date: May 1, 1997

Creator: Lund, S.M. & Barnard, J.J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Emittance growth in heavy ion rings due to effects of space charge and dispersion

We review the derivation of moment equations which include the effects of space charge and dispersion in bends first presented in ref [1]. These equations generalize the familiar envelope equations to include the dispersive effects of bends. We review the application of these equations to the calculation of the change in emittance resulting from a sharp transition from a straight section to a bend section, using an energy conservation constraint. Comparisons of detailed 2D and 3D simulations of… more

Date: June 3, 1998

Creator: Barnard, J.J., LLNL

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

LLNL review of the 1994 accelerator production of tritium (APT) concept

LLNL was asked in September 1994 to review the accelerator production of tritium (APT) concept as it had evolved up to the fall of 1994. The purpose was not to compare it to other sources of tritium, but to identify possible technical flaws in the concept and to assess feasibility. The APT concept reviewed was based on a 1.0 GeV normal conducting proton linac operating CW at currents up to 200 mA with a target of tungsten and blanket of {sup 3}He and lead. The LLNL review group concurs with the… more

Date: March 8, 1995

Creator: Alesso, H.P.; Barnard, J.J. & Booth, R.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Progress toward a prototype recirculating induction accelerator for heavy-ion fusion

The US Inertial Fusion Energy (IFE) Program is developing induction accelerator technology toward the goal of electric power production using Heavy-Ion beam-driven inertial Fusion (HIF). The recirculating induction accelerator promises driver cost reduction by repeatedly passing the beam through the same set of accelerating and focusing elements. The authors present plans for and progress, toward a small (4.5-m diameter) prototype recirculator which will accelerate K{sup +} ions through 15 laps… more

Date: April 28, 1995

Creator: Friedman, A.; Barnard, J.J. & Cable, M.D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Status of experiments leading to a small recirculator

A heavy ion linear induction accelerator is considered to be the leading driver candidate for an Inertial Fusion Energy reactor. To deliver a space-charge-dominated beam at the appropriate energy (several GeV), such an accelerator would be several kilometers in length. Since total length has a strong influence on accelerator cost, we are considering the potential advantages and practical implementation of a recirculating induction accelerator. To address the critical scientific and technical ch… more

Date: January 16, 1998

Creator: Sangster, C.T.; Barnard, J.J. & Cianciolo, T.V.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

On the relaxation of semi-Gaussian and K-V beams to thermal equilibrium

A beam propagating in a continuous, linear focusing channel tends to relax to a thermal equilibrium state. We employ nonlinear conservation constraints to theoretically analyze changes in quantities that characterize both an initial semi-Gaussian beam with a matched rms beam envelope and a K-V beam under a relaxation to thermal equilibrium. Results from particle-in-cell simulations are compared to the theoretical predictions.

Date: May 2, 1995

Creator: Lund, S.M.; Barnard, J.J. & Miller, J.M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Workshop on Accelerators for Heavy Ion Fusion: Summary Report of the Workshop

The Workshop on Accelerators for Heavy Ion Fusion was held at Lawrence Berkeley National Laboratory May 23-26, 2011. The workshop began with plenary sessions to review the state of the art in HIF (heavy ion fusion), followed by parallel working groups, and concluded with a plenary session to review the results. There were five working groups: IFE (inertial fusion energy) targets, RF approach to HIF, induction accelerator approach to HIF, chamber and driver interface, ion sources and injectors.

Date: April 29, 2011

Creator: Seidl, P.A. & Barnard, J.J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Course Notes: United States Particle Accelerator School Beam Physics with Intense Space-Charge

The purpose of this course is to provide a comprehensive introduction to the physics of beams with intense space charge. This course is suitable for graduate students and researchers interested in accelerator systems that require sufficient high intensity where mutual particle interactions in the beam can no longer be neglected. This course is intended to give the student a broad overview of the dynamics of beams with strong space charge. The emphasis is on theoretical and analytical methods of… more

Date: May 30, 2008

Creator: Barnard, J.J. & Lund, S.M.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Direct Drive Heavy-Ion-Beam Inertial Fusion at High Coupling Efficiency

Issues with coupling efficiency, beam illumination symmetry and Rayleigh Taylor (RT) instability are discussed for spherical heavy-ion-beam-driven targets with and without hohlraums. Efficient coupling of heavy ion beams to compress direct-drive inertial fusion targets without hohlraums is found to require ion range increasing several-fold during the drive pulse. One-dimensional implosion calculations using the LASNEX ICF target physics code shows the ion range increasing four-fold during the d… more

Date: June 25, 2007

Creator: Logan, B. Grant; Logan, B. Grant; Perkins, L.J. & Barnard, J.J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Vacuum requirements for heavy ion recirculating induction linacs

We examine the requirements of the vacuum system for the LLNL/LBL recirculating induction linac concept. We reexamine processes, including beam stripping, background gas ionization, intra-beam charge exchange and desorption of gas molecules from the wall due to the incident ionized gas molecules and stripped ions, in the context of the proposed recirculator. We discuss implications for the vacuum system layout and estimate the cost of such a system. 18 refs., 2 figs., 1 tab.

Date: December 1, 1990

Creator: Barnard, J.J.; Yu, S.S. (Lawrence Livermore National Lab., CA (USA)) & Faltens, A. (Lawrence Berkeley Lab., CA (USA))

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

NDCX-II, A New Induction Linear Accelerator for Warm Dense Matter Research

The Heavy Ion Fusion Science Virtual National Laboratory (HIFS-VNL), a collaboration between Lawrence Berkeley National Laboratory (LBNL), Lawrence Livermore National Laboratory (LLNL), and Princeton Plasma Physics Laboratory (PPPL), is currently constructing a new induction linear accelerator, called Neutralized Drift Compression eXperiment NDCX-II. The accelerator design makes effective use of existing components from LLNL's decommissioned Advanced Test Accelerator (ATA), especially induction… more

Date: June 1, 2009

Creator: Leitner, M.; Bieniosek, F.; Kwan, J.; Logan, G.; Waldron, W.; Barnard, J.J. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Physics Design and Scaling of Elise

Elise is an electrostatically focused heavy-ion accelerator being designed and constructed at Lawrence Berkeley Laboratory. The machine is intended to be the first half of the four-beam Induction Linac Systems Experiment (ILSE), which ultimately will test the principal beam dynamics issues and manipulations of induction heavy-ion drivers for inertial fusion. Elise will use an existing 2 MeV injector and will accelerate space-charge-dominated pulses to greater than 5 MeV. The design objective of… more

Date: August 1, 1995

Creator: Lee, E. P.; Bangerter, R. O.; Chan, C. F.; Faltens, S.; Henetroza, E.; Hahn, K. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department