H. Hojo

S. Oikawa

T. Watanabe

Y. Matsumoto

National Institute for Fusion Science (NIFS-Repository)

Proton-Boron fusion reactor (p_ll B reactor)( L = 1.5 m , = 0.1 m , U = 0.7 , oU = 0.2 )0.1( b ) F0WCf)1021 103X m-;Z-;>;:m<1020 102101 102 103T, Tp_EFF ( KEV)( a )en0..o0..IIFig.2 Ignition condition for fusion reactors. Pc and PE are powerdensities released by charged particles and by bremsstrahlung.Boron temperature Tb is assumed to be 1b/Tp_ef f = 1/20. Theregion of 7J > 1 (colored part) shows that the ignition is possible.Fig.1 Line-tying effect for stabilization of LHD plasma.IGNITION CONDITION FOR FUSION REACTORSIt was theoretically predicted that steady state dis-tribution of ICRF heated proton become quasilinearplateau distribution function (QPDF) due to runawayion heating process1). The fusion reaction rate of p_ll Bis calculated assuming QPDF for protons and ignitioncondition for p_ll B reactor is estimated (Fig.2). Possi-bility for ICRF sustained p_ll B reactor is shown./VACUUM VESSEL'iDIVERTER FIELD LINE(!3lers 15%)2P1cfs U 2B'5/2/1Q L ou IT = 0.15· .. ,p + 11 B --+ 3a + 8.7 MeV§ 23. Ignition Condition of Proton-BoronFusion Reactor')Watanabe, T., Hojo, H. (Plasma Res., Univ. ofTsukuba)Matsumoto, Y., Oikawa, S. (Hokkaido Univ., Eng.)has a potentiality for the ultimate energy resource on theearth. Because, the fuels (proton and boron) are ubiqui-tous on the earth and fast neutrons are not generated. Ithas been, however, considered, in the p-11 B reactor thatbremsstrahlung power loss is too large to satisfy the igni-tion condition, because the atomic number of boron is solarge (ZB = 5). But, the progress of LHD experimentaland theoretical studies have brought a new prospect forthe p_ll B reactor.A remarkable loss of the high energetic particle is notfound in the ICRF experiment of LHD and the energyspectrum of the accelerated protons has extended evento 500kcV-range. This result agrees with the predictionclarified by the particle orbit calculation, which showthat MeV-range protons are produced and confined byICRF heating in LHD (Ba;l: = 3T). It is shown that ac-celerated protons can selectively absorb the energy fromICRF wave. Then, runaway ion heating process occursin ICRF heating in LHD 1).The plasma disruption caused by the high beta is notyet observed in LHD, even if the beta value go beyondthe traditional theoretical limit. It is shown theoreti-cally that LHD has potentiality of the high beta plasmaconfinement2). The chaotic field line-layer plays a keyrole for an efficient plasma confinement in LHD. Steepdensity gradient in peripheral region can be stabilized bythe line-tying effect of lines of force (Fig.1). Stabilizingeffect of conducting end plates is studied by the varia-tional principle. The critical pressure gradient in chaoticfield line region in LHD is estimated as follows.where Plefs is the plasma pressure at the last close fluxsurface, the width of chaotic field line region, L thefield line length to vacuum vessel wall, U the specificvolume, Bo the magnetic field intensity, respectively.Reference1) Watanabe, T., et al., NIFS-PROC-53, 24 (2003)2) Watanabe, T., J. Plasma Fusion Res. SERIES, 5, 487(2002)200

Ignition Condition of Proton-Boron Fusion Reactor

Abstract

Similar works

Full text

Available Versions

National Institute for Fusion Science (NIFS-Repository)