Quadrupole image-current effects in the ITS 6-MeV, 4-kA linac

Author

Allison, Paul ; Moir, David C.

Author_Institution

Los Alamos Nat. Lab., NM, USA

Volume

1

fYear

1997

fDate

12-16 May 1997

Firstpage

1141

Abstract

The eight accelerating cells for the ITS linear induction accelerator (LIA) are driven with two 50-Ω lines at 250 kV for 60 ns. The wall return currents for the 4-kA beam then pass through these lines, generating a weak steady-state quadrupole field of ~3 G integrated strength on axis, which causes a small asymmetry in the nominally round beam at the linac exit. Beam-dynamics simulations with the particle-tracing code SCHAR show that if uncorrected, this would increase the beam emittance at the end of the DARHT 20-MeV linac, therefore quadrupole-corrector coils (QC) were added to each cell, in addition to the existing dipole steering coils. Measurements of the asymmetry of the ITS beam as a function of excitation current of these corrector coils are in good agreement with simulations, giving confidence that there will be negligible emittance degradation from this effect for DARHT

Keywords

accelerator magnets; collective accelerators; electromagnets; high energy physics instrumentation computing; linear accelerators; particle beam diagnostics; particle beam dynamics; 20 MeV; 250 kV; 3 G; 4 kA; 50 ohm; 6 MeV; 60 ns; DARHT linac; ITS linac; SCHAR code; accelerating cells; asymmetry measurements; beam emittance; beam-dynamics simulations; dipole steering coils; linear induction accelerator; particle-tracing code; quadrupole image-current effects; quadrupole-corrector coils; wall return currents; weak steady-state quadrupole field; Acceleration; Coils; Current measurement; Degradation; Induction generators; Linear accelerators; Linear particle accelerator; Particle beam measurements; Particle beams; Steady-state;

fLanguage

English

Publisher

ieee

Conference_Titel

Particle Accelerator Conference, 1997. Proceedings of the 1997

Conference_Location

Vancouver, BC

Print_ISBN

0-7803-4376-X

Type

conf

DOI

10.1109/PAC.1997.749955

Filename

749955