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The H-/D- RF source at the edge towards large area beam extraction and
long pulses
W. Kraus, R. Riedl, Ch. Day*, M. Dremel*, H.-D. Falter, U. Fantz, P. Franzen, B.
Heinemann, M. Fröschle, Ch. Martens, P. McNeely, E. Speth
Max-Planck-Institut für Plasmaphysik, EURATOM Association, Postfach 1533, D-85740
Garching, Germany
* Forschungszentrum Karlsruhe / Institute for Technical Physics, Herrmann–von–Helmholtz–
Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
Abstract: IPP Garching is currently developing a RF source for the ITER neutral beam system.
It has already been demonstrated at the test facility BATMAN that the IPP RF source can
achieve and partially exceed the ITER requirements with respect to current density, pressure
and electron content, but with only small extraction area (~70 cm²) and limited pulse length
(< 6 s) [1]. On the “MANITU” testbed (multi ampere negative ion test unit) the experiments
are focussed on large area beam extraction and operation in D- with pulses of up to 3600 s.
In first experiments with pulses of few seconds’ length the extraction area has been
enlarged from the initially 74 cm² in two steps to 152 cm² and 306 cm². The electrically
measured H- current density showed no significant dependence on the extraction area. In
order to demonstrate long pulse operation many components of the RF source and of the
power supply as well as of the testbed had to be upgraded.
The paper describes this upgrade and contains first results concerning extended
extraction area and pulse length.
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Synopsis (pdf)