Measurement and simulation of the UMERbeam in the sourceregion
As the beam propagates in the University of Maryland Electron Ring (UMER) complex transverse density structure including halos has been observed. A primary objective of the experiment is to understand the evolution of a space-charge-dominated beam as it propagates over a substantial distance. It is therefore important to understand which details of the beam structure result from propagation of the beam in the ring and which characteristics result from the specific details of the initial distribution. Detailed measurements of the initial beam characteristics have therefore been performed. These include direct measurement of the density using a phosphor screen, as well as pepper pot measurements of the initial transverse distribution function. Detailed measurements of the distribution function have also been obtained by scanning a pinhole aperture across a beam diameter, and recording phosphor screen pictures of the beam downstream of the pinhole. Simulations of the beam characteristics in the gun region have also been performed using the WARP P.I.C. code. From these simulations, the observed behavior has been attributed to a combination of perturbations to the transverse distribution by a cathode grid that is used to modulate the beam current, as well as the complex transverse dynamics that results from the combination of the nonlinear external focusing fields of the gun structure and the nonlinear space charge forces.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Director. Office of Science. Office of Fusion EnergySciences. Contracts DE-AC03-76SF00098 and DE-FG02-02ER54672 andDE-FG02-94ER40855 and W-7405-ENG-48
- DOE Contract Number:
- DE-AC02-05CH11231
- OSTI ID:
- 861586
- Report Number(s):
- LBNL-55967; HIFAN 1346; R&D Project: Z41001; BnR: AT5015031; TRN: US200601%%204
- Resource Relation:
- Conference: 15th International Symposium on Heavy IonInertial Fusion HIF2004, Princeton, NJ,06/7-11/2004
- Country of Publication:
- United States
- Language:
- English
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