Survey of the TS-ECE Discrepancy and recent investigations in ICRF heated plasmas at Alcator C-Mod
1 Massachusetts Institute of Technology, Cambridge, MA, USA
2 University of Texas, Austin, TX, USA
3 University of Wisconsin, Madison, WI, USA
4 CompX, CA, USA
5 Oak Ridge Institute for Science and Education (ORISE), Oak Ridge, TN, USA
This paper reports on a new investigation of the long-standing, unresolved discrepancy between Thomson Scattering (TS) and Electron Cyclotron Emission (ECE) measurements of electron temperature in high temperature tokamak plasmas. At the Alcator C-Mod tokamak, ion cyclotron range of frequency (ICRF) heating is used to produce high temperature conditions where the TS- ECE discrepancy, as observed in the past at JET and TFTR, should appear. Plasmas with Te(0) up to 8 keV are obtained using three different heating scenarios: Ion Cyclotron Resonance Heating (ICRH), ICRF mode conversion heating and a combination of the two heating methods. This is done in order to explore the hypothesis that ICRH-generated fast ions may be related to the discrepancy. In all high temperature cases at C-Mod, we find no evidence for the type of discrepancy reported at JET and TFTR. Here we present the C-Mod results along with a summary of past work on the TS-ECE discrepancy.
© Owned by the authors, published by EDP Sciences 2012