Abstract
The measurement of low-Z impurities, in particular He ash, in the core of International Thermonuclear Experimental Reactor (ITER) remains an outstanding diagnostic issue. The only credible candidate at present is active charge exchange recombination spectroscopy (CER) utilizing a diagnostic neutral beam (DNB) optimized for the dual requirements of beam penetration and charge exchange cross section, resulting in beam energies of 2∼100 keV/AMU. Using the existing ITER parameter profile and equilibrium data files and reasonable assumptions regarding viewing optics and DNB performance, we have employed a benchmarked multistep beam penetration code to yield signal-to-noise estimates for possible core helium concentration measurements. These studies confirm the importance of precise determination of beam intensities via accurate modeling and independent measurement, as well as the need for beam modulation, to satisfy the stated measurement precisions needed for ITER. Comparable calculations have been done for an intense pulsed neutral beam based on ion diode technology, as well as other candidate He-CER wavelengths, to assess the relative advantages of these techniques. Since any DNB-based diagnostic system actually deployed on ITER will likely be used for a variety of purposes, signal-to-noise calculations for the related active CER measurement of ion temperatures have also been performed and will be presented.
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Thomas, D.M., Burrell, K.H., Wade, M.R., Snider, R.T. (1998). Prospects for Core Helium Density and Related Measurements on ITER Using Active Charge Exchange. In: Stott, P.E., Gorini, G., Prandoni, P., Sindoni, E. (eds) Diagnostics for Experimental Thermonuclear Fusion Reactors 2. Springer, Boston, MA. https://doi.org/10.1007/978-1-4615-5353-3_44
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DOI: https://doi.org/10.1007/978-1-4615-5353-3_44
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