Conveners
Transport of Energetic Particles
- William W. Heidbrink (University of California Irvine)
This presentation examines the energetic particle transport induced by saturated kink modes and sawtooth crashes in JET deuterium plasmas. It is known that kink mode-resonant transport[1-3] and phase-space redistribution from sawtooth crashes[4-5] can drive strong fast ion transport with dependencies on particle pitch and energy. Measurements with JET's Faraday cup fast ion loss detector array...
We study the effect of a sawtooth crash on the dynamics of MeV-class fast deuterons, as produced by ion cyclotron heating, and alpha particles in the energy range 35-3500 keV, resembling helium ash and newly-born fusion alphas. The simulations are performed using the hybrid code MEGA [1], which solves visco-resistive MHD equations for the bulk plasma and drift-kinetic equations with...
Energetic particle transport due to the energetic-particle-driven magnetohydrodynamic (MHD) instabilities in existing fusion devices has been intensively studied in order to find a way to control/reduce the energetic deuterium-tritium fusion born alpha particle transport in a future fusion reactor. In the hydrogen Large Helical Device (LHD) plasma experiment, a study of energetic ion...
The understanding of energetic particle (EP) dynamics in plasmas is crucial for the conception and operation of magnetic confinement devices. These energetic particles have an energy much higher than the thermal energy of the bulk plasma, and despite their low density, can destabilize magnetohydrodynamics (MHD) modes. These modes can provoke the rapid ejection of energetic particles from the...
Kinetic-magnetohydrodynamic hybrid simulations were performed to investigate the linear growth and the nonlinear evolution of off-axis fishbone mode (OFM) destabilized by trapped energetic ions in tokamak plasmas. The spatial profile of OFM is mainly composed of $m/n = 2/1$ mode inside the $q=2$ magnetic flux surface while the $m/n = 3/1$ mode is predominant outside the $q=2$ surface, where...
It is known that MHD instability driven by energetic particles called EIC is excited in high ion temperature mode with high power perpendicular NBI heating in LHD [1]. The EIC has been observed by measuring temperature fluctuations and local magnetic field fluctuations, but the overall structure of the EIC is not well understood.
In this study, we introduce a data assimilation method based...
An imaging neutral particle analyzer (INPA) [1] provides energy and radially resolved measurements of the confined fast-ion (FI) population ranging from the high-field side to the edge on the midplane of the DIII-D tokamak. In recent experiments, a neutral beam modulation technique is employed to diagnose FI flow in the INPA-interrogated phase-space driven by multiple, marginally unstable...
Edge localized modes (ELMs) are inherent to a transport barrier at the tokamak plasma edge. While there have been extensive theoretical as well as simulational studies on the ELM characteristics, there are relatively few studies on the effects of ELMs on fast-ion transport [1]. Here, by employing the nonlinear gyrokinetic theory, we develop a theoretical analysis of the fast-ion transport...
Beam ion losses have been observed in AUG discharges during the plasma current ramp-up phase and during disruptions. The velocity-space of the escaping, and ccelerated, beam ions has been measured with the poloidal FILD array available at AUG [1]. Tomographic reconstruction techniques [2] applied to the FILD data revealed, with unprecedented detail, the velocity-space distribution of the lost...
Resonant magnetic field perturbation (RMP) coils are used in multiple fusion devices to mitigate magnetohydrodynamic (MHD) instabilities known as edge localised modes. The coils produce a radial magnetic field component that is small compared to the toroidal field strength, but breaks the axi-symmetry of the flux surfaces near the edge. This increases heat and particle transport at the plasma...
Externally applied resonant magnetic perturbations (RMPs), which are useful for suppressing Edge Localized Modes, modify the axisymmetric equilibrium fields on DIII-D, altering the confinement of fast ions and leading to increased prompt losses from beam ions born inside the last closed flux surface (LCFS). The light ion beam probe (LIBP) technique [1] uses beam ions to probe internal magnetic...
