Abstract
A shielded residual gas analyzer RGA system on Tore Supra can function during plasma operation
and is set up to monitor the composition of the neutral gas in one of the pumping ducts of the
toroidal pumped limited. This “diagnostic RGA” has been used in long-pulse up to 6 min
discharges for continuous monitoring of up to 15 masses simultaneously. Comparison of the
RGA-measured evolution of the H2 /D2 isotopic ratio in the exhaust gas to that measured by an
energetic neutral particle analyzer in the plasma core provides a way to monitor the evolution of
particle balance. RGA monitoring of corrective H2 injection to maintain proper minority heating is
providing a database for improved ion cyclotron resonance heating, potentially with RGA-base
feedback control. In very long pulses 4 min absence of significant changes in the
RGA-monitored, hydrocarbon particle pressures is an indication of proper operation of the actively
cooled, carbon-based plasma facing components. Also H2 could increase due to thermodesorption of
overheated plasma facing components. © 2010 American Institute of Physics.
