Title :
Intense electron beam disruption due to ion release from surfaces
Author :
Vermare, C. ; Davis, H.A. ; Hughes, T.P. ; Moir, D.C. ; Olson, R.T. ; Wood, W.M.
Author_Institution :
Los Alamos Nat. Lab., NM, USA
Abstract :
A major concern for the DARHT second axis (2 kA, 18.6 MeV, 2000 ns) is that ions or ionized neutrals released from solid surfaces (e.g., apertures, septum, dumps, and targets) by beam impact can be accelerated and trapped by the beam potential. This positive charge will be electrically attracted to the beam and could disrupt it. To study this, experiments were performed on the DARHT first axis. Here, the beam, focused to a range of diameters, is transmitted through thin foils made of various materials. The time-dependent beam radial profile is measured downstream of the target. For low current density (depending on the material used), the downstream-beam profile is time invariant as expected. At higher current density, the downstream-beam radius changes during the pulse followed by transverse instability. Data, particle-in-cell simulations, and comparisons are presented.
Keywords :
electron accelerators; electron beams; linear accelerators; particle beam diagnostics; particle beam stability; 18.6 keV; DARHT; beam profile; beam radius; electron beam disruption; ion release; particle-in-cell simulation; surfaces; time-dependent beam radial profile; transverse instability; Acceleration; Apertures; Current density; Electron beams; Ion beams; Laboratories; Laser excitation; Particle beams; Radiography; Structural beams;
Conference_Titel :
Pulsed Power Plasma Science, 2001. PPPS-2001. Digest of Technical Papers
Conference_Location :
Las Vegas, NV, USA
Print_ISBN :
0-7803-7120-8
DOI :
10.1109/PPPS.2001.1001893