Conceptual design studies of ionization gauges for the measurement of neutral gas density at high pressures and high magnetic fields

摘要

Time resolved information about the neutral gas density at various positions inside fusion reactors is essential for machine control and for the understanding of physical processes at the plasma edge. The ASDEX pressure gauge [1] is a specially designed ionization manometer that is able to measure the density of neutral gas in the presence of strong magnetic fields and with high time resolution in present-day fusion machines. The requirements in terms of accessible pressure range and magnetic field strength increase drastically along with more powerful reactors in the future. While pressure gauges at ASDEX Upgrade operate in magnetic fields of up to 3 T, manometers in ITER will have to cope with fields of 8 T. Similarly, the neutral gas pressure in the divertor of ITER is expected to reach considerably higher values of up to 0.2 mbar in partially detached states [2]. Going even further towards fully detached plasma scenarios which are required for the DEMO reactor, the neutral gas pressure is expected to reach considerably higher values. The aim of this contribution is to assess the suitability of ionization gauges that are based on the so-called Schulz-Phelps design to cope with thus high neutral gas pressures and magnetic fields.