Energetic Particle Physics on the HL-2A Tokamak: A Review

Abstract

Interaction between shear Alfvén wave (SAW) and energetic particles (EPs) is one of major concerns in magnetically confined plasmas since it may lead to excitation of toroidal symmetry breaking collective instabilities, thus enhances loss of EPs and degrades plasma confinement. In the last few years, Alfvénic zoology has been constructed on HL-2A tokamak and series of EPs driven instabilities, such as toroidal Alfvén eigenmodes (TAEs), revered shear Alfvén eigenmodes (RSAEs), beta induced Alfvén eigenmodes (BAEs), Alfvénic ion temperature gradient (AITG) modes and fishbone modes, have been observed and investigated. Those Alfvénic fluctuations show frequency chirping behaviors through nonlinear wave-particle route, and contribute to generation of axisymmetric modes by nonlinear wave-wave resonance in the presence of strong tearing modes. It is proved that the plasma confinement is affected by Alfvénic activities from multiple aspects. The RSAEs resonate with thermal ions, and this results in an energy diffusive transport process while the nonlinear mode coupling between core-localized TAEs and tearing modes trigger avalanche electron heat transport events. Effective measures have been taken to control SAW fluctuations and the fishbone activities are suppressed by electron cyclotron resonance heating. Those experimental results will not only contribute to better understandings of energetic particles physics, but also provide technology bases for active control of Alfvénic modes on International Thermonuclear Experimental Reactor (ITER) and Chinese Fusion Engineering Testing Reactor (CFETR).

Development of the ion cyclotron emission diagnostic on the HL-2A tokamak

“…A rich experimental study on EPs physics and EP induced instabilities has been carried out on HL-2A tokamak with the help of a powerful auxiliary heating system [23][24][25][26][27][28]. The neutral beam injection (NBI) system consists of two independent beamlines, both beamlines are co-injected into the HL-2A tokamak tangentially with an injection angle of 58.1 • .…”

Development of a 105 GHz fast ion collective Thomson scattering diagnostic on HL-2A tokamak

“…Fast ions originated from auxiliary neutral beam injection or ion cyclotron resonance heating have become a major concern in magnetic confinement fusion, since those energetic particles provide free energy for excitation of multitudinous Alfvenic modes [1,2], which may degrade the fast ion confinement and affect the bulk plasma dynamics [3][4][5][6]. Collective Thomson scattering (CTS) diagnostic, a powerful tool for mapping out the fast ion phase space distribution by providing spatially localized measurements of the ion velocity distribution, is firstly used to measure the fast ion evolution on JET [7].…”

A simulation study of a windowless gas stripping room in an E//B neutral particle analyzer

“…The energetic particles, also known as fast, superthermal, hot and high-energy particles, are expected to play a critical role in plasma heating, current drive, momentum transport, energy transfer and plasma stability [14,15]. Many experimental and theoretical studies have been contributed to this field [16][17][18][19][20], and other related fields [21][22][23][24][25][26] recently. Aiming to study the frontier physics of the energetic particles and to measure the fuel ratio, a new E//B NPA has been designed in the present experimental devices [27].…”