Objectives
Measurement of the neutral gas fluxes into the divertor region, pumping duct, and the outside midplane in the presence of strong magnetic fields
Detectors, Diagnostic Method
Linear tetrode with hot cathode
(similar to the usual ionization gauges)
Chopping emission current to pick up the minute ion current
(related to the concept of lock-in amplifier)
Installed eleven gauges in the vacuum vessel
Specifications
| Measurable range | : from ultra high vacuum to several Pascal |
| Vessel temperature | : up to 400C |
| Magnetic fields | : up to 5.4 Tesla |
| Time response | : 3 - 4 ms (determined by conductance) |
| Chevron in front of gauge head | |
| : to avoid plasma exposure : to provide thermalization of particles |
|
Acknowledgement
We would like to thank Dr. G. Haas at ASDEX, and Dr. J. Ehrenberg at JET for their discussion at the occasion of introducing the fast ionization gauges.
