A Fast Exhaust-Gas Analyzer for the ITER Fusion Experiment Divertor

• Published in: IEEE transactions on plasma science Vol. 38; no. 3; pp. 315 - 319
• Main Authors: Klepper, C.C., Carlson, E.P., Moschella, J.J., Hazelton, R.C., Keitz, M.D., Gardner, W.L.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: New York, NY IEEE 01.03.2010; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Analyzers; Breakdown; Breakdown voltage; Divertor; Electrodes; Emissions; Exact sciences and technology; Gases; helium exhaust; helium removal; High voltages; Hydrogen; ITER; Light emission; Magnetic analysis; Magnetic confinement and equilibrium; Magnetic field measurement; Magnetic fields; Magnetic heads; Magnetic sensors; Maintenance; Optical (ultraviolet, visible, infrared) measurements; Optical sensors; Physics; Physics of gases, plasmas and electric discharges; Physics of plasmas and electric discharges; Plasma; Plasma diagnostic techniques and instrumentation; Plasma measurements; Power exhaust; divertors; Radio frequencies; Radio frequency; residual gas analysis; Sensors; Stimulated emission; Tokamaks; Thermonuclear reactors; ITER tokamak; Hydrogen; helium removal; Divertor; Magnetic field effects; Maintenance; Experimental study; Helium; Design; Concentration measurement; Plasma diagnostics; Light emission; residual gas analysis; Magnetic confinement; Exhaust gases; Fusion reactor divertors; Residual gas; Confined plasma; ITER; helium exhaust; Magnetic fields
• ISSN: 0093-3813; 1939-9375
• DOI: 10.1109/TPS.2009.2037742

This paper presents a first demonstration of a radio-frequency (RF)-excited optical gas analyzer (RF-OGA) designed to quantitatively measure minority species inside the neutralization region of the ITER fusion experiment divertor. The sensor head, which creates its own plasma excitation and plasma light emission, is designed to operate in a strong magnetic field, and the RF coupling leads to bright light emission. It also allows for operation at low voltages, avoiding the radiation-enhanced breakdowns expected when high voltages are present in the ITER environment. Furthermore, the preferred sensor head features full isolation of the metal RF electrodes from the induced plasma. This ¿electrodeless¿ operation will permit long operation without frequent maintenance. The testing of a first experimental RF-OGA with an electrodeless design in a strong (~2-T) magnetic field showed a mostly linear response of the He I-6678 A¿ line emission to the He concentration in a hydrogen background, which would produce a He concentration measurement accurate to within 2% of the helium-to-hydrogen ratio.