Physics analyses on the core plasma properties in the helical fusion DEMO reactor FFHR-d1

Physics assessments on magnetohydrodynamics equilibrium, neoclassical transport and alpha particle confinement have been carried out for the helical fusion DEMO reactor FFHR-d1, using radial profiles extrapolated from the Large Helical Device. Large Shafranov shift is foreseen in FFHR-d1 due to its high-beta property. This leads to deterioration in neoclassical transport and alpha particle confinement. Plasma position control using vertical magnetic field has been examined and shown to be effective for Shafranov shift mitigation. In particular, in the high-aspect-ratio configuration, it is possible to keep the magnetic surfaces similar to those in vacuum with high central beta of ~8% by applying a proper vertical magnetic field. As long as the Shafranov shift is mitigated, the neoclassical heat loss can be kept at a level compatible with the alpha heating power. The alpha particle loss can also be kept at a low level if the loss boundary of alpha particles is on the blanket surface and the plasma position control is properly applied. The lost positions of alpha particles are localized around the divertor region that is located behind the blanket in FFHR-d1.

[1]  H. Yamada,et al.  Self-sustained detachment in the Large Helical Device , 2006 .

[2]  Takashi Shimozuma,et al.  Goal and Achievements of Large Helical Device Project , 2010 .

[3]  Y. Takeiri,et al.  Scalings of energy confinement and density limit in stellarator/heliotron devices , 1990 .

[4]  L. L. Lao,et al.  A global simulation study of ICRF heating in the LHD , 2006 .

[5]  Osamu Mitarai,et al.  Design activities on helical DEMO reactor FFHR-d1 , 2012 .

[6]  T. Morisaki,et al.  Characteristics of the Global Energy Confinement and Central Pressure in LHD , 2010 .

[7]  A. Sagara,et al.  Direct extrapolation of radial profile data to a self-ignited fusion reactor based on the gyro-Bohm model , 2011 .

[8]  C. D. Beidler,et al.  Neoclassical Transport Scalings Determined from a General Solution of the Ripple-Averaged Kinetic Equation (GSRAKE) , 1995 .

[9]  J. Harris,et al.  Characterization of energy confinement in net-current free plasmas using the extended International Stellarator Database , 2005 .

[10]  W. A. Cooper,et al.  Impact of heat deposition profile on global confinement of NBI heated plasmas in the LHD , 2003 .

[11]  H. Yamada,et al.  Formularization of the confinement enhancement factor as a function of the heating profile for FFHR-d1 core plasma design , 2012 .

[12]  Masao Okamoto,et al.  Finite β Effects on the ICRF and NBI Heating in the Large Helical Device , 1995 .

[13]  Chihiro Suzuki,et al.  Development and application of real-time magnetic coordinate mapping system in the Large Helical Device , 2012 .

[14]  Hiroshi Yamada,et al.  Neoclassical transport optimization of LHD , 2002 .

[15]  E. D. Fredrickson,et al.  Initial results from coaxial helicity injection experiments in NSTX , 2001 .

[16]  N. Nakajima,et al.  Effects of global MHD instability on operational high beta-regime in LHD , 2005 .

[17]  A. Wakasa,et al.  Effect of Neoclassical Transport Optimization on Electron Heat Transport in Low-Collisionality LHD Plasmas , 2007 .

[18]  Kozo Yamazaki,et al.  Configuration flexibility and extended regimes in Large Helical Device , 2001 .

[19]  William A. Fowler,et al.  Thermonuclear Reaction Rates, III , 1967 .

[20]  H. Yamada,et al.  Characterization and operational regime of high density plasmas with internal diffusion barrier observed in the Large Helical Device , 2007 .

[21]  H. Yamada,et al.  Advanced Operational Regime with Internal Diffusion Barrier on LHD , 2010 .

[22]  Hideo Sugama,et al.  Development of a Non-Local Neoclassical Transport Code for Helical Configurations , 2008 .

[23]  M. Itagaki,et al.  Monte Carlo Study Based on a Real Coordinate System for Tangentially Injected High-Energy Particles in the Large Helical Device , 2010 .

[24]  J. C. Whitson,et al.  Steepest‐descent moment method for three‐dimensional magnetohydrodynamic equilibria , 1983 .

[25]  H. Yamada,et al.  Density limit study focusing on the edge plasma parameters in LHD , 2008 .

[26]  A. Sagara,et al.  Design Window Analysis for the Helical DEMO Reactor FFHR-d1 , 2012 .

[27]  R. Sakamoto,et al.  An evaluation of fusion gain in the compact helical fusion reactor FFHR-c1 , 2013 .

[28]  K. Kawahata,et al.  Interferometer Systems on LHD , 2010 .

[29]  Paul H Rutherford,et al.  Introduction to Plasma Physics , 1995 .

[30]  S. Wolfe,et al.  A new look at density limits in tokamaks , 1988 .

[31]  H. Yamada,et al.  Characteristics of MHD Equilibrium and Related Issues on LHD , 2010 .

[32]  I. Yamada,et al.  Recent Progress of the LHD Thomson Scattering System , 2010 .

[33]  A. W. Trivelpiece,et al.  Introduction to Plasma Physics , 1976 .

[34]  H. Yamada,et al.  Density Limits for the Core and Edge Plasmas Related to the Local Temperatures in LHD , 2010 .

[35]  M. Shoji,et al.  Compatibility between high energy particle confinement and magnetohydrodynamic stability in the inward-shifted plasmas of the Large Helical Device , 2002 .

[36]  L. Giannone,et al.  Radiation power profiles and density limit with a divertor in the W7-AS stellarator , 2002 .

[37]  H. Sugama,et al.  Reduction of turbulent transport with zonal flows enhanced in helical systems. , 2008, Physical review letters.

[38]  R. A. Dory,et al.  SPECIAL TOPIC: Energy confinement scaling from the international stellarator database , 1995 .

[39]  Michel Howard Kevin,et al.  Development and application of HINT2 to helical system plasmas , 2006 .

[40]  M. Shoji,et al.  Observation of stable superdense core plasmas in the large helical device. , 2006, Physical review letters.

[41]  S. Murakami,et al.  Study of α-particle confinement in an LHD-type heliotron reactor , 2013 .

[42]  H. Yamada,et al.  Study of MHD Stability in LHD , 2010 .