Measurement of helium gas in a deuterium environment
In order to detect helium in a deuterium gas environment a detector has been developed which is based on spectroscopic measurement techniques. For the excitation of the helium and deuterium atoms, different electron sources have been tested. The best line emitting light source was found to be a Penning gauge. The light is collected in an optical fibre bundle, transferred away from the tokamak experiment to a more easily accessible area, split by interference filters into D(alpha) light and the light of a strong He I line, and detected by photomultipliers. Unfortunately, broad spectral lines from the deuterium molecule superimpose the stongest He I lines and have nearly the same intensity as the helium lines at a He concentration of about 5%. Therefore, some effort is necessary to deduce the partial pressures of helium and deuterium. A method is described which yields the calibration factors for the observed nonlinear pressure response of the spectral lines. The lower limit for the determination of the helium concentration presently amounts to about 1%-2% and the time resolution of the system is of the order of a few milliseconds.
Bibliographic Reference: Article: Review of Scientific Instruments, Vol. 63 (1992) No. 1, pp. 1-7
Record Number: 199210528 / Last updated on: 1994-12-02
Original language: en
Available languages: en