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Suppression of microwave instabilities

Published online by Cambridge University Press:  09 March 2009

I. Hofmann
Affiliation:
Gesellschaft für Schwerionenforschung m.b.h., Darmstadt, West Germany

Abstract

The longitudinal resistive microwave instability in storage rings has been identified in previous workshops as a key problem in heavy ion fusion. Here we show by means of computer simulation that the predictions from the linearized theory of instability are over-pessimistic in the case of non-relativistic ions. This is due to an early nonlinear saturation of the instability caused by the formation of a thin stabilizing tail of the momentum distribution, which provides enough Landau damping to suppress further growth. The main condition for this non-destructive self-stabilization lies in the slow resistive growth rate, as compared with the large coherent frequency shift induced by space charge. The important conclusion from this is a significant extension of the stable storage ring filling time to values that are comfortable from a design point of view. For the HIBALL reactor driver accelerator a safe storage time of 5 to 10 msec is expected, instead of only 1 msec according to the linearized theory e-folding times.

Type
Research Article
Copyright
Copyright © Cambridge University Press 1985

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References

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