Studies of electron temperature fluctuations in the core of Alcator C-Mod plasmas via correlation electron cyclotron emission

Transport in tokamak plasmas is higher than predicted by neoclassical theory; this anomalous transport is believed to be attributed to turbulent fluctuations. New Correlation Electron Cyclotron Emission (CECE) experiments on Alcator C-Mod show lower levels of electron temperature fluctuations in the saturated ohmic confinement (SOC) regime than in the linear ohmic confinement (LOC) regime, however the lineaveraged density fluctuation data collected from ohmic plasmas previously showed the opposite trends. The apparent contradiction is explained by a change in the dominant turbulence modes in each confinement regime. Linear stability analysis shows that the LOC regime is dominated by trapped electron mode (TEM) turbulence and the SOC regime is on the border between the ion temperature gradient (ITG) and TEM turbulence modes being dominant. It is reasonable to believe that the TEM turbulence mode drives electron temperature fluctuations, which explains the higher electron temperature fluctuation levels seen in the LOC regime compared to the SOC regime.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Nuclear Science and Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2013

Author dc:creator

• Oi, Curran Y. M

Advisor dc:contributor.advisor

• Anne E. White.

• Nuclear Science and Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/82446

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/82446