Abstract

To investigate the experimentally observed interaction between beam ion species and fast Alfvén wave (FW), a Monte Carlo code, ORBIT-RF [V. S. Chan, S. C. Chiu, and Y. A. Omelchenko, Phys. Plasmas 9, 501 (2002)], which solves the time-dependent Hamiltonian guiding center drift equations, has been upgraded to incorporate a steady-state neutral beam ion slowing-down distribution, a quasilinear high harmonic radio frequency diffusion operator and the wave fields from the two-dimensional ion cyclotron resonance frequency full wave code (TORIC4) [M. Brambilla, Plasma Phys. Controlled Fusion 41, 1 (1999)]. Comparison of ORBIT-RF simulation of power absorption with fixed amplitudes of FW fields from TORIC4 power absorption calculation, which assumes Maxwellian plasma distributions, attains agreement within a factor of two. The experimentally measured enhanced neutron rate is reproduced to within 30% from ORBIT-RF simulation using a single dominant toroidal and poloidal wave number.

Highlights

  • In burning plasma physics experiments such as International Thermonuclear Experimental ReactorITER,1 both neutral beam injectionNBIand fast Alfvén waveFWin the ion cyclotron resonance frequenciesICRFswill be employed for auxiliary heating and current drive

  • The presence of energetic ion species can modify the plasma behavior in important ways such as magnetohydrodynamicMHDstabilization or destabilization and momentum transport/plasma rotation by the ICRF generated energetic tails. These issues relating the interaction between the ICRF wave and energetic ions must be well understood for successes of future tokamak experiments and achievement of ITER physics goals

  • Among many experimental results in the DIII-D tokamak5–9 using different frequency ranges60– 117 MHzat different harmonicsfourth–eighth, we focus on the experiments performed during 1998 campaign for fourth harmonic central damping of 60 MHz FW on injected deuterium beam ions

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Summary

INTRODUCTION

In burning plasma physics experiments such as International Thermonuclear Experimental ReactorITER, both neutral beam injectionNBIand fast Alfvén waveFWin the ion cyclotron resonance frequenciesICRFswill be employed for auxiliary heating and current drive. Previous numerical analysis on the experimental measurements in DIII-D tokamak has been done using similar simple Fokker–Planck model and the ICRF code Power deposition for ION cyclotron resonance heatingPION.. Previous numerical analysis on the experimental measurements in DIII-D tokamak has been done using similar simple Fokker–Planck model and the ICRF code Power deposition for ION cyclotron resonance heatingPION.8 These approaches do not take into account both finite orbit width of non-Maxwellian ions produced from the radio frequencyrfinteraction and the radial.

EXPERIMENTAL CONDITIONS IN THE DIII-D TOKAMAK
Modeling of steady-state slowing-down distribution of beam ions
Quasilinear high harmonic RF diffusion operator
Collision operators
ORBIT-RF NUMERICAL RESULTS
Approach used for TORIC4 modeling
TORIC4 simulation results for a specific DIII-D discharge
Approach for coupling of TORIC4 full wave solution to ORBIT-RF
The ORBIT-RF simulation results
Comparison of ORBIT-RF simulation results with experimental measurements
SUMMARY AND FUTURE PLAN
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