Title :
A particle simulation study of self-bias potential for plasma ion confinement in multiple-pulse radiography
Author :
Lin Yen ; Kwan, Thomas J. T.
Author_Institution :
Appl. Phys. Div., Los Alamos Nat. Lab., NM, USA
Abstract :
Summary form only given, as follows. The intense deposition of energy on to a high-Z target from a high current relativistic electron beam produces bremsstrahlung photons which can be used to generate radiographs of a dynamically evolving object. The interaction of the intense electron beam with the target can generate plasmas from the target surface. Consequently, a column of plasma ions expands away from the target due to the space charge potential of the electron beam. This expansion can lead to a larger beam spot size resulting in degradation of spatial resolution of radiographic images. Previous studies have shown that a self-biased electric potential between the target and the collimator can confine the ion column and maintain the electron beam spot size. In this work a two-dimensional particle-in-cell code is used to study a novel target configuration in which the converter target and the beam dump are connect electrically to maintain the self-biased potential in multiple-pulse radiography such as in the second axis of DARHT. Our simulation study showed that the self-bias electric potential between the target and the collimator was effective in confining the ions emitted from the target during multiple-pulse operation. The effects of the inductance of the target chamber on the decay time of the self-biased potential are also examined.
Keywords :
bremsstrahlung; plasma confinement; plasma diagnostics; plasma simulation; radiography; DARHT; bremsstrahlung photons; electron beam spot size; high current relativistic electron beam; high-Z target; intense electron beam; intense energy deposition; ion column; multiple-pulse operation; multiple-pulse radiography; particle simulation study; plasma ion confinement; radiographic images; self-bias electric potential; self-bias potential; self-biased electric potential; space charge potential; two-dimensional particle-in-cell code; Collimators; Degradation; Electric potential; Electron beams; Particle beams; Plasma confinement; Plasma simulation; Radiography; Space charge; Spatial resolution;
Conference_Titel :
Plasma Science, 2002. ICOPS 2002. IEEE Conference Record - Abstracts. The 29th IEEE International Conference on
Conference_Location :
Banff, Alberta, Canada
Print_ISBN :
0-7803-7407-X
DOI :
10.1109/PLASMA.2002.1030525