Simultaneous H/D/T and 3He/4He absolute concentration measurements with an optical Penning gauge on JET

Abstract

The Optical Penning (or Species-Selective Penning) Gauge technique is used for the measurement of the H2/D2/T2 fuel isotopic composition and He/D2 concentration in the neutralized particle exhaust of fusion devices. An Optical Penning detection system has already been used in JET during its first deuterium-tritium campaigns (DTE1) and has been chosen by ITER. Recent improvements to the sub-divertor diagnostic suite as well as the optical instrumentation, in preparation for the next DT campaign, have improved the optical throughput of the measurement and enabled 3He/D2 detection down to 0.1 %. For the first time, the 3He/4He isotopic ratio can be measured simultaneously with the H/D/T ratio. This technique is of particular interest for ion cyclotron resonance frequency (ICRF) heating scenarios.