Abstract Details
| status: | file name: | submitted: | by: |
|---|---|---|---|
| approved | ballooning_limit_of_nstx_pedestals_using_a_novel_gyro.pdf | 2025-03-11 14:50:32 | Michail Anastopoulos Tzanis |
Abstracts
Author: Michail S. Anastopoulos Tzanis
Requested Type: Poster
Submitted: 2025-03-11 14:45:16
Co-authors: M. Yang, G.M. Staebler, J.F. Parisi, P.B. Snyder
Contact Info:
Oak Ridge National Laboratory
1 Bethel Valley Road
Oak Ridge, 37830
USA
Abstract Text:
The EPED model [1] had success in describing type-I ELM and QH mode pedestals in conventional tokamaks, by combining peeling-ballooning (PB) and kinetic ballooning mode (KBM) constraints. The KBM constraint, calculated via the ballooning critical pedestal (BCP) technique [1], takes an approximate form w_ped∼c_1 (β_(p,ped) )^(c_2 ), with c_1∼0.07-0.10 and c_2∼0.5 [2] at moderate aspect ratio. However, it is both experimentally observed, and calculated via BCP, that typical values of c_1 and c_2 are higher at low aspect ratio [2][3][4]. It has also been noted that differences between local MHD and gyrokinetic (GK) ballooning stability can be larger at low aspect ratio [5]. KBM critical pedestals (including kinetic effects) are consistent with observation in initial studies on conventional and spherical tokamaks.
In this work, the application of a reduced model for the calculation of the ballooning stability boundary is presented based on a novel developed Gyro-Fluid System (GFS) [6]. The impact of geometry and impurities is examined and compared to MHD ballooning stability. The geometry affects the ballooning stability due to its effect on the curvature and trapped particle contribution, while impurities have an impact on the pedestal temperature. The applicability of the model is examined on NSTX-like pedestals. GFS captures kinetic ballooning modes and the wide pedestal scaling of NSTX opening the route for the integration of this reduced model to EPED.
1 P.B. Snyder et al 2011 Nucl. Fusion 51 103016
2 R.J. Groebner et al 2013 Nucl. Fusion 53 093024
3 S.F. Smith et al 2022 Plasma Phys. Control. Fusion 64 045024
4 A. Diallo et al 2013 Nucl. Fusion 53 093026
5 J. F. Parisi et al 2024 Nucl. Fusion 64 054002
6 G.M. Staebler et al 2023 Phys. Plasmas 30 102501
This work was supported by the US Department of Energy, Office of Science, Basic Energy, Office of Science, Basic Energy Sciences Program under ORNL contract numbers DE-AC05-00OR22725
Characterization: 1.0
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