Author: Tobos, L.
Paper Title Page
TUZO04 Space Charge Compensation Measurements of Multicharged Ion Beams Extracted from an ECR Ion Source 38
 
  • D. Winklehner
    LBNL, Berkeley, California, USA
  • D.G. Cole, D. Leitner, G. Machicoane, F. Marti, L. Tobos
    NSCL, East Lansing, Michigan, USA
 
  Space charge compensation* due to the interaction of the beam with residual gas molecules is a well-known phenomenon for high current injector beam lines. For beam lines using mostly magnetic focusing elements and for pressure above 10-6 mbar, full neutralization has been observed. However, due to the low pressure required for the efficient transport of high charge state ions, beams in ECR injector lines are typically only partly neutralized. With the performance increase of the next generation ECR ion sources it is possible to extract tens of mA of beam current. In this high current regime, non-linear focusing effects due to the space-charge potential of the beam become more and more important. In order to develop a realistic simulation model for low energy beam transport lines, it is important to estimate the degree of space charge compensation. In this contribution we report on measurements of the beam potential (and neutralization), performed after the extraction region of the ECR ion source, in dependence of the base pressure in the beam line and other source parameters using a Retarding Field Analyzer (RFA). Results are discussed and compared to simulations.
* When the beam interacts with the residual gas, electrons are separated from gas molecules and accumulate inside the beam envelope, thereby compensating the space-charge (aka neutralization)
 
slides icon Slides TUZO04 [4.192 MB]