Studying high-energy particles is important since alpha particles are produced in the future reactors. In the Large Helical Device (LHD) high-energy tail reached up to 500 keV by minority heating in the inward shifted magnetic configuration. To know the limit of confinement of high-energy particles in the LHD, it is necessary to produce higher-energy particles. Higher harmonic ICRF heating is thought to be more effective to produce high-energy particles than minority heating since selectively high-energy particles are accelerated due to the finite Larmor radius effect.
To calculate the distribution function of higher harmonic ICRF heated plasma, a bounce-averaged Fokker-Planck equation was used. Ions are accelerated in the perpendicular direction at ion cyclotron resonance layer by ICRF heating. Therefore a pitch-angle increases until the turning points of banana orbit reach the cyclotron resonance layer. As the result the 'butterfly' structure is made. In this calculation helical symmetric hydrogen plasma was assumed and wave number parallel to magnetic field was assumed to be 0. Cold plasma approximation was used to calculate the polarity and wave number perpendicular to the magnetic field. According to the orbit calculation, the particle with the energy over 1 MeV cannot be confined in the LHD. Therefore loss term was added to the Fokker-Planck equation. The high-energy tail was limited below 1 MeV. In the second harmonic heating, tail temperature increases with energy in low energy region. And with NBI the high-energy tail was enhanced.