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Title: Transient Beam Dynamics in the LBL 2 MV Injector

Abstract

A driver-scale injector for the Heavy Ion Fusion Accelerator project has been built at LBL. This machine has exceeded the design goals of high voltage (> 2 MV), high current (> 0.8 A of K{sup +}) and low normalized emittance (< 1 {pi} mm-mr). The injector consists of a 750 keV gun pre-injector followed by an electrostatic quadrupole accelerator (ESQ) which provides strong (alternating gradient) focusing for the space-charge dominated beam, and simultaneously accelerates the ions to 2 MeV. A matching section is being built to match the beam to the electrostatic accelerator ELISE. The gun preinjector, designed to hold up to 1 MV with minimal breakdown risks, consists of a hot aluminosilicate source with a large curved emitting surface surrounded by a thick ''extraction electrode''. During beam turn-on the voltage at the source is biased from a negative potential, enough to reverse the electric field on the emitting surface and avoid emission, to a positive potential to start extracting the beam; it stays constant for about 1 {micro}s, and is reversed to turn-off the emission. Since the Marx voltage applied on the accelerating quadrupoles and the main pre-injector gap is a long, constant pulse (several {micro}s), the transient behaviormore » is dominated by the extraction pulser voltage time profile. The transient longitudinal dynamics of the beam in the injector was simulated by running the Particle in Cell codes GYMNOS and WARP3d in a time dependent mode. The generalization and its implementation in WAIW3d of a method proposed by Lampel and Tiefenback to eliminate transient oscillations in a one-dimensional planar diode will be presented.« less

Authors:
;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
15013501
Report Number(s):
UCRL-ID-137045
TRN: US0600176
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ACCELERATORS; BEAM DYNAMICS; BREAKDOWN; DESIGN; ELECTRIC FIELDS; ELECTROSTATIC ACCELERATORS; ELECTROSTATICS; FOCUSING; HEAVY IONS; IMPLEMENTATION; LAWRENCE BERKELEY LABORATORY; OSCILLATIONS; QUADRUPOLES; SPACE CHARGE; TRANSIENTS

Citation Formats

Henestroza, E, and Grote, D. Transient Beam Dynamics in the LBL 2 MV Injector. United States: N. p., 1999. Web. doi:10.2172/15013501.
Henestroza, E, & Grote, D. Transient Beam Dynamics in the LBL 2 MV Injector. United States. doi:10.2172/15013501.
Henestroza, E, and Grote, D. Tue . "Transient Beam Dynamics in the LBL 2 MV Injector". United States. doi:10.2172/15013501. https://www.osti.gov/servlets/purl/15013501.
@article{osti_15013501,
title = {Transient Beam Dynamics in the LBL 2 MV Injector},
author = {Henestroza, E and Grote, D},
abstractNote = {A driver-scale injector for the Heavy Ion Fusion Accelerator project has been built at LBL. This machine has exceeded the design goals of high voltage (> 2 MV), high current (> 0.8 A of K{sup +}) and low normalized emittance (< 1 {pi} mm-mr). The injector consists of a 750 keV gun pre-injector followed by an electrostatic quadrupole accelerator (ESQ) which provides strong (alternating gradient) focusing for the space-charge dominated beam, and simultaneously accelerates the ions to 2 MeV. A matching section is being built to match the beam to the electrostatic accelerator ELISE. The gun preinjector, designed to hold up to 1 MV with minimal breakdown risks, consists of a hot aluminosilicate source with a large curved emitting surface surrounded by a thick ''extraction electrode''. During beam turn-on the voltage at the source is biased from a negative potential, enough to reverse the electric field on the emitting surface and avoid emission, to a positive potential to start extracting the beam; it stays constant for about 1 {micro}s, and is reversed to turn-off the emission. Since the Marx voltage applied on the accelerating quadrupoles and the main pre-injector gap is a long, constant pulse (several {micro}s), the transient behavior is dominated by the extraction pulser voltage time profile. The transient longitudinal dynamics of the beam in the injector was simulated by running the Particle in Cell codes GYMNOS and WARP3d in a time dependent mode. The generalization and its implementation in WAIW3d of a method proposed by Lampel and Tiefenback to eliminate transient oscillations in a one-dimensional planar diode will be presented.},
doi = {10.2172/15013501},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1999},
month = {12}
}

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