Proton-Boron fusion reactor (p-¹¹B Reactor)
p + ¹¹ B → 3 α + 8.7 MeV
probably offers the ultimate energy resource on the earth, because, 1) the fuels (Proton and Boron) are ubiquitous on the earth , and 2) fast neutrons are not generated. The side-reaction
p + ¹¹B → n + ¹¹C - 2.8 MeV
is an endothermal reaction and produces only slow neutrons when energy of proton exceed about 3MeV or more.

It has been, however, considered, in the Proton-Boron fusion reactor that bremsstrahlung power loss is too large to satisfy the ignition condition[1], because the atomic number of boron is so large (Z_B=5 ). But, the progress of LHD experimental and theoretical studies have brought a new prospect for the Proton-Boron fusion reactor, i.e., (1)Production and confinement of high-energy particles by ICRF heating in the LHD and (2)Possibility of high β plasma confinement in LHD[2].

Particle orbits under ICRF heating in LHD is solved numerically. This study shows the following results. (1)The high-energy ion is heated further more by preferentially absorbing the RF energy, i.e., the runaway ion heating mode progresses. (2) LHD can confine fusion relevant high-energy ( MeV range) protons. (3)The LHD magnetic field can confine high-energy ions in the almost entire magnetic surface region[3]. Runaway ion heating process is analyzed by Langevin equation. It is shown that the steady state proton distribution function becomes a quasilinear plateau distribution function (QPDF). Nuclear fusion reaction rate < σ v > is derived assuming a QPDF for protons, and an ignition condition of p-¹¹B reactor is analyzed and are shown to be possible to be satisfied.

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