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First Demonstration of Resonant Pitch-Angle Scattering of Relativistic Electrons by Externally-Launched Helicon Waves

Fuente: arXiv

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Bibliographic Details
Main Authors:	Choudhury, H., Battey, A., Paz-Soldan, C., Lestz, J., Leuthold, N., Lvovskiy, A., Marini, C., Barr, J., Heidbrink, W., Spong, D., Tang, S., Van Compernolle, B., Zhang, Q., Zhang, Y., Tang, X.
Format:	Preprint
Published:	2025
Subjects:	Plasma Physics
Online Access:	Acceder al recurso
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_version_	1866908379025244160
author	Choudhury, H. Battey, A. Paz-Soldan, C. Lestz, J. Leuthold, N. Lvovskiy, A. Marini, C. Barr, J. Heidbrink, W. Spong, D. Tang, S. Van Compernolle, B. Zhang, Q. Zhang, Y. Tang, X.
author_facet	Choudhury, H. Battey, A. Paz-Soldan, C. Lestz, J. Leuthold, N. Lvovskiy, A. Marini, C. Barr, J. Heidbrink, W. Spong, D. Tang, S. Van Compernolle, B. Zhang, Q. Zhang, Y. Tang, X.
contents	Helicon waves satisfying the normal wave-particle cyclotron resonance are observed to limit the growth and maximum energy of relativistic electrons (REs) in low-density Ohmic DIII-D tokamak plasmas. Following the application of helicon waves, pitch-angle scattering of high-energy REs causes an increase in both synchrotron and electron-cyclotron emissions. The hard x-ray emission, a proxy for the RE population, ceases to grow; and energy-resolved hard x-ray measurements also show a striking decrease in the number of high-energy REs (above the resonance at approximately \SI{8}{MeV}) to below the noise floor. This occurs despite the toroidal electric field remaining high enough to drive exponential RE growth in the absence of helicon waves. These results open new directions for limiting the maximum energy of RE populations in laboratory and fusion plasmas.
format	Preprint
id	arxiv_https___arxiv_org_abs_2505_19279
institution	arXiv
publishDate	2025
record_format	arxiv
spellingShingle	First Demonstration of Resonant Pitch-Angle Scattering of Relativistic Electrons by Externally-Launched Helicon Waves Choudhury, H. Battey, A. Paz-Soldan, C. Lestz, J. Leuthold, N. Lvovskiy, A. Marini, C. Barr, J. Heidbrink, W. Spong, D. Tang, S. Van Compernolle, B. Zhang, Q. Zhang, Y. Tang, X. Plasma Physics Helicon waves satisfying the normal wave-particle cyclotron resonance are observed to limit the growth and maximum energy of relativistic electrons (REs) in low-density Ohmic DIII-D tokamak plasmas. Following the application of helicon waves, pitch-angle scattering of high-energy REs causes an increase in both synchrotron and electron-cyclotron emissions. The hard x-ray emission, a proxy for the RE population, ceases to grow; and energy-resolved hard x-ray measurements also show a striking decrease in the number of high-energy REs (above the resonance at approximately \SI{8}{MeV}) to below the noise floor. This occurs despite the toroidal electric field remaining high enough to drive exponential RE growth in the absence of helicon waves. These results open new directions for limiting the maximum energy of RE populations in laboratory and fusion plasmas.
title	First Demonstration of Resonant Pitch-Angle Scattering of Relativistic Electrons by Externally-Launched Helicon Waves
topic	Plasma Physics
url	https://arxiv.org/abs/2505.19279