I finished my diploma thesis on beam instabilities induced by ions in November 1995.
published as: BONN-IB-95-40
Title:
Theoretische und experimentelle Untersuchungen zu
Vielteilcheneffekten bei der Elektronen-Stretcher-Anlage ELSA
Abstract:
In electron storage rings the circulating electrons interact with the
residual gas and ionize molecules producing positive ions. The ions
can be trapped by the electrical field of the electron beam.
Trapped ions have many deterious effects
on the electron beam, for example tune shift, emittance blow up and
transverse instabilities. These effects limit the performance of
the 3.5 GeV Electron Stretcher Accelerator ELSA for high beam
currents, especially in storagemode operation. To understand the conditions
which favour ion trapping the dynamics of the ion motion has been
investigated by simulations. Moreover several methods to minimize
the impact of ions on the beam quality have been tested and implemented
into routine operation. Important beam parameters like lifetime and
emittance have been improved up to a factor of three for high beam currents
above 200 mA. Transverse coherent instabilities between the electron
beam and the ion cloud could be successfully suppressed.
Talks/Conference Contibutions about Ion Trapping:
CSteier@lbl.gov