Initial Experimental Results from the Alcator C-Mod Compact Neutral Particle Analyzer
Abstract
Recent experimental results from the new Compact Neutral Particle Analyzer (CNPA) and a completed multi-detector upgrade of the diagnostic are presented. The CNPA uses Si diodes to detect charge-exchanged (CX) induced energetic (>20keV) neutral particles for ICRF hydrogen minority tail temperature diagnosis. A diagnostic neutral beam (DNB) provides the neutrals for the CX process. The discussed data involve measurements of the on-axis Hydrogen-minority perpendicular energy spectrum during low density (n_eo ∼ 10^20/m^3) ICRF D(H) plasmas with 0.5 to 1.5MW of ICRF. During these discharges, tail temperatures reached ∼ 200keV. The energy spectrum is compared with TRANSP and Stix-distribution based calculations, and central ICRF power deposition densities are inferred. The upgrade consists of the installation of three additional detectors which provides the diagnostic with multiple sightlines. Using a new long-pulse DNB, the improved CNPA will give spatial and temporal tail temperature measurements for moderate (n_eo ∼ 2x10^20/m^3) densities C-Mod D(H) plasmas.
- Publication:
-
APS Division of Plasma Physics Meeting Abstracts
- Pub Date:
- November 2004
- Bibcode:
- 2004APS..DPPCP1014T