Accession Number : ADA307976

Title :   Use of an Active Wire B sub Theta Cell for Electron Beam Conditioning.

Descriptive Note : Interim rept.,

Corporate Author : NAVAL RESEARCH LAB WASHINGTON DC

Personal Author(s) : Murphy, D. P. ; Myers, M. C. ; Antoniades, J. A. ; Fernsler, R. F. ; Meger, R. A.

PDF Url : ADA307976

Report Date : 19 APR 1996

Pagination or Media Count : 36

Abstract : The propagation of intense, relativistic electron beams in air is subject to the resistive hose instability. Conditioning the beam prior to injecting it into the air can extend its range by reducing the hose growth rate and by reducing the initial spatial perturbations that seed the hose instability. Experiments have been performed using the SuperIBEX accelerator (Ipeak = 10-30 kA, E = 4.5 MeV, 40 ns FWHM) and various conditioning cells to suppress hose. This paper describes the performance of an active wire B, cell that was used in conjunction with an IFR cell. The IFR cell detunes the instability by producing a head-to-tail radius taper on the beam. The wire cell maintains this radius taper while producing an emittance taper that is necessary to suppress the hose growth. In addition, the wire cell reduces the initial beam perturbations through the anharmonic centering force associated with the wire current and its azimuthal magnetic field Be. The ability of the Be cell to reduce the beam offset with a minimal increase in the beam radius gives it several advantages over the use of a simple, thick scattering foil to perform the radius taper to emittance taper conversion. The SuperIBEX beam propagation distance, in terms of the betatron oscillation scale length, was extended to approx. 10lambdabeta using these cells.

Descriptors :   *ELECTRON BEAMS, *BEAM FORMING, CONVERSION, CONTROL, SPATIAL DISTRIBUTION, THICKNESS, SCATTERING, MAGNETIC FIELDS, SURVIVABILITY, EMITTANCE, WAVE PROPAGATION, LONG RANGE(DISTANCE), PERTURBATIONS, TAPER, OSCILLATION, INSTABILITY, RELATIVITY THEORY, BETATRONS.

Subject Categories : Particle Accelerators

Distribution Statement : APPROVED FOR PUBLIC RELEASE