A survey of pedestal magnetic fluctuations using gyrokinetics and a global reduced model for microtearing stability
- Univ. of Texas, Austin, TX (United States). Institute for Fusion Studies; General Atomics, Energy & Advanced Concepts, DIII-D
- Univ. of Texas, Austin, TX (United States). Institute for Fusion Studies
- Columbia Univ., New York, NY (United States)
- Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Ain Shams Univ., Cairo (Egypt)
- General Atomics, San Diego, CA (United States)
- Univ. of California, Los Angeles, CA (United States)
- Institute of Plasma Physics and Laser Microfusion (IPPLM) Warsaw (Poland)
- KTH Royal Inst. of Technology, Stockholm (Sweden)
- Culham Science Centre, Abingdon (United Kingdom). Culham Centre for Fusion Energy (CCFE)
This article presents a global reduced model for slab-like microtearing modes (MTMs) in the H-mode pedestal, which reproduces distinctive features of experimentally observed magnetic fluctuations, such as chirping and discrete frequency bands at noncontiguous mode numbers. Our model, importantly, includes the global variation of the diamagnetic frequencies, which is necessary to reproduce the experimental observations. The key insight underlying this model is that MTM instability is enabled by the alignment of a rational surface with the peak in the profile of the diamagnetic frequency. Conversely, MTMs are strongly stabilized for toroidal mode numbers for which these quantities are misaligned. This property explains the discrete fluctuation bands in several DIII-D and JET discharges, which we survey using our reduced model in conjunction with global gyrokinetic simulations. A fast yet accurate reduced model for MTMs enables rapid interpretation of magnetic fluctuation data from a wide range of experimental conditions to help assess the role of MTM in the pedestal.
- Research Organization:
- General Atomics, San Diego, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Fusion Energy Sciences (FES)
- Contributing Organization:
- JET Contributors
- Grant/Contract Number:
- FC02-04ER54698; AC02-05CH11231; AC02-09CH11466; SC0019004; FG02-04ER54742; AC05-00OR22725; FG02-04ER54761
- OSTI ID:
- 1867242
- Alternate ID(s):
- OSTI ID: 1862720
- Journal Information:
- Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 4 Vol. 29; ISSN 1070-664X
- Publisher:
- American Institute of Physics (AIP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Similar Records
Microtearing modes as the source of magnetic fluctuations in the JET pedestal
Time-dependent experimental identification of inter-ELM microtearing modes in the tokamak edge on DIII-D