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17–22 Oct 2016
Kyoto International Conference Center
Japan timezone

Evidence for Trapped Electron Mode Turbulence in MST Improved Confinement RFP Plasmas

20 Oct 2016, 08:30
4h
Kyoto International Conference Center

Kyoto International Conference Center

Takaragaike, Sakyo-ku, Kyoto 606-0001 Japan
Poster EXD - Magnetic Confinement Experiments: Plasma–material interactions; divertors; limiters; scrape-off layer (SOL) Poster 5

Speaker

Dr David Brower (UCLA)

Description

Drift wave turbulence underlies key transport phenomena in toroidal, magnetically confined plasmas. While long-studied for the tokamak and stellarator configurations, the distinguishing features of the reversed field pinch (RFP) allow further development of gyrokinetic models that build on the RFP’s features of high-beta, large magnetic shear (tending to add stability), and relatively weak toroidal field. Since the RFP is poloidal-field-dominated, the role of ballooning is considerably weaker. Standard RFP behavior tends to be governed by tearing magnetic fluctuations driven by the gradient in the current density. However, tokamak-like improved confinement occurs with inductive profile control (PPCD: pulsed poloidal current drive), and large-scale electromagnetic fluctuations are largely suppressed. [1] In this environment, gyro-scale instabilities are anticipated important and could ultimately limit confinement. [2] The role of drift waves is rapidly emerging for the RFP, and this provides a complementary environment to other configurations for exploring basic understanding of turbulent-driven-transport physics and improving confidence in predictive capability for future burning plasmas. Herein we describe detailed measurements of high-frequency density fluctuation spectral features and temporal-spatial dynamics in the MST-RFP. Comparison with modeling results from the gyrokinetic GENE code provide evidence that these fluctuations are consistent with expectations for TEM turbulence and may indeed be playing a role in governing the overall plasma confinement. Work supported by U.S. DOE, Office of Science, Office of Fusion Energy Sciences under Award Numbers DE-FC02-05ER54814, DE-FG02-85ER53212, and DE-FG02-01ER54615. [1] J.S. Sarff, et al., Nuclear Fusion 43,1684-1692 (2003). [2] D. Carmody, et al., Phys. Plasmas 22, 012594 (2015).
Country or International Organization USA
Paper Number EX/P5-17

Primary author

Dr David Brower (UCLA)

Co-authors

Dr B.E. Chapman (University of Wisconsin-Madison) Dr Eli Parke (UCLA) Prof. J.S. Sarff (University of Wisconsin-Madison) Mr James Duff (University of Wisconsin-Madison) Dr Liang Lin (UCLA) Dr M.J. Pueschel (University of Wisconsin-Madison) Prof. P.W. Terry (University of Wisconsin-Madison) Dr W.X. Ding (UCLA) Mr Z. Williams (University of Wisconsin-Madison)

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