Micro-tearing mode dominated electron heat transport in DIII-D H-mode pedestal

被引：8

作者：

Chen, J. ^{[1
]}

Jian, X. ^{[2
]}

Brower, D. L. ^{[1
]}

Haskey, S. R. ^{[3
]}

Yan, Z. ^{[4
]}

Groebner, R. ^{[5
]}

Wang, H. Q. ^{[5
]}

Rhodes, T. L. ^{[1
]}

Laggner, F. ^{[3
]}

Ding, W. ^{[1
]}

Barada, K. ^{[1
]}

Banerjee, S. ^{[3
]}

机构：

[1] Univ Calif Los Angeles, Los Angeles, CA 90095 USA

[2] Univ Calif San Diego, San Diego, CA 92093 USA

[3] Princeton Plasma Phys Lab, Princeton, NJ 08543 USA

[4] Univ Wisconsin Madison, Madison, WI 53706 USA

[5] Gen Atom, San Diego, CA 92186 USA

来源：

NUCLEAR FUSION | 2023年 / 63卷 / 06期

关键词：

micro-tearing modes; magnetic fluctuation; electron heat transport; pedestal; TRANSITION;

D O I：

10.1088/1741-4326/accafb

中图分类号：

O35 [流体力学]; O53 [等离子体物理学];

学科分类号：

070204 ; 080103 ; 080704 ;

摘要：

A new, comprehensive set of evidence reveals that Micro-Tearing Modes (MTMs) dominate pedestal electron heat transport in an H-mode experiment in the DIII-D tokamak. The experiment investigates the role of MTMs by scanning pedestal collisionality, a main drive of MTM instability, from 0.43 to 0.84 on the pedestal top. Broadband (150-800 kHz) magnetic and density fluctuations originating from the pedestal gradient region and highly consistent with MTMs are observed, with amplitude increasing during the scan. The higher magnetic fluctuation amplitude correlates with a lower pedestal electron temperature gradient, implying MTMs may regulate the pedestal electron heat transport. The collisionality scan results in profile and transport changes consistent with predicted transport capability of MTMs: (1) experimentally-determined electron heat diffusivity increases similar to 40% at the location where the broadband density fluctuations peak; (2) ion heat diffusivity has less increase (<20%); and (3) a locally flattened region in the electron temperature pedestal is observed at high collisionality. A local, linear gyrokinetic simulation finds MTMs as the most unstable mode in the pedestal gradient region. In addition, local, nonlinear simulations suggest MTMs can dominate and drive experimentally-relevant, megawatt-level electron heat flux. This result establishes MTMs as an effective transport mechanism in the H-mode pedestal, in particular at high collisionality.

引用

页数：11