DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 49: Multifield Measurement of Low-n Alfven Eigenmodes in the Core of DIII-D Plasmas | ||
| Name: | Raffi Nazikian ( |
Affiliation: | Princeton Plasma Physics Laboratory |
| Research Area: | Energetic Particles | Presentation time: | Requested | Co-Author(s): | G. McKee, M. VanZeeland, W.W. Heidbrink, N.N. Gorelenkov, G.J. Kramer |
| Description: | Simultaneous measurements of the radial ECE and BES profile of low-n Alfvenic modes will be performed in order to distringuish the role of plasma compressibility vs radial displacement in the multifield structure and amplitude of AEs. The experiment will focus on beam driven RSAEs and TAEs in coinjection plasmas. In counter injection plasmas the study will focus on the n=0 mode and the high-n RSAEs. The objective of this study is to determine the applicability and limitation of the ideal MHD closure relation in the description of the observed mode activity. A key goal is to determine whether electron compressibility is relevant to the description of AEs in DIII-D over a wide range of frequencies from 10-200 kHz. A second goal is to determine if the mode polarization in the plasma core can be reliably determined from BES/ECE simultaneous measurements by comparing the inferred polarization against the polarization of external magnetic measurements. | ||
| Experimental Approach/Plan: | Establish equivalent discharge to 128556, co injection, normal current direction. Scan the BES array across the plasma (some limited scanning is needed). Add co/counter beam blips to identify and document the counter beam driven modes. | ||
| Background: | Experiments in 2006 proved that the electron response is inconsistent with ideal MHD for some modes. The extended radial BES array will allow the definitive identification of the breakdown of ideal MHD closure in the description of low and high frequency AEs. The work will ultimately impact on the interpretation of mode amplitudes and in the computation of fast ion transport associated with these modes. | ||
| Resource Requirements: | 210 beams are necessary. | ||
| Diagnostic Requirements: | BES, ECE, FIDA,... | ||
| Analysis Requirements: | NOVAK, TRANSP, ... | ||
| Other Requirements: | -- | ||
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