Neutral Gas Pressure Gauge

Partial pressure of D2 and He gas under the baffle and around main plasma are measured.

[Diagnostic Method]
Intensity of Da and HeI from penning discharge region depend on partial pressure of D2 and He gasses. Da and HeI emission are guided to the diagnostic hall with optical fiber and measured by photomultiplier tubes with bandpass filter.

Detector: Photomultiplier tubes with bandpass filters
・ Time resolution: ~4 ms (Sampling time)
{Pressure response are delayed about 0.1 sec from those in the vacuum vessel, because the guages are placed about 4 m away from vacuum vessel}
・ Position
around main plasma: P-9 section, U1-2&U2-2 port
under the baffle: P-10 U2-2 port