Verification of Energetic-Particle-Induced Geodesic Acoustic Mode in Gyrokinetic Particle Simulations
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Abstract
The energetic-particle-induced geodesic acoustic mode (EGAM) is studied using gyrokinetic particle simulations in tokamak plasmas. In our simulations, exponentially growing EGAMs are excited by energetic particles with a slowing-down distribution. The frequencies of EGAMs are always below the frequencies of GAMs, which is due to the non-perturbative contribution of energetic particles (EPs). The mode structures of EGAMs are similar to the corresponding mode structures of GAMs. Our gyrokinetic simulations show that a high EP density can enhance the EGAM growth rate, due to high EP free energy, and that EPs' temperature and the pitch angle of the distribution modify the EGAM frequency/growth rate by means of the resonance condition. Kinetic effects of the thermal electrons barely change the EGAM frequency, and have a weak damping effect on the EGAM. Benchmarks between the gyrokinetic particle simulations and a local EGAM dispersion relation exhibit good agreement in terms of EGAM frequency and growth rate.
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Yang Chen, Wenlu Zhang, Jian Bao, Zhihong Lin, Chao Dong, Jintao Cao, Ding Li. Verification of Energetic-Particle-Induced Geodesic Acoustic Mode in Gyrokinetic Particle Simulations[J]. Chin. Phys. Lett., 2020, 37(9): 095201. DOI: 10.1088/0256-307X/37/9/095201
Yang Chen, Wenlu Zhang, Jian Bao, Zhihong Lin, Chao Dong, Jintao Cao, Ding Li. Verification of Energetic-Particle-Induced Geodesic Acoustic Mode in Gyrokinetic Particle Simulations[J]. Chin. Phys. Lett., 2020, 37(9): 095201. DOI: 10.1088/0256-307X/37/9/095201
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Yang Chen, Wenlu Zhang, Jian Bao, Zhihong Lin, Chao Dong, Jintao Cao, Ding Li. Verification of Energetic-Particle-Induced Geodesic Acoustic Mode in Gyrokinetic Particle Simulations[J]. Chin. Phys. Lett., 2020, 37(9): 095201. DOI: 10.1088/0256-307X/37/9/095201
Yang Chen, Wenlu Zhang, Jian Bao, Zhihong Lin, Chao Dong, Jintao Cao, Ding Li. Verification of Energetic-Particle-Induced Geodesic Acoustic Mode in Gyrokinetic Particle Simulations[J]. Chin. Phys. Lett., 2020, 37(9): 095201. DOI: 10.1088/0256-307X/37/9/095201
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