| Co-Investigator(Kenkyū-buntansha) |
NAKAO Yasuyuki Kyushu University, Faculty of Engineering, Professor, 大学院・工学研究院, 教授 (00164129)
KUDO Kazuhiko Kyushu University, Faculty of Engineering, Professor, 大学院・工学研究院, 教授 (40039681)
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| Budget Amount *help |
¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 2005: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2004: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Research Abstract |
The effects of nuclear elastic scattering (NES) on (a) energy transfer to plasma ions and electrons and (b) T(d,n)^4He fusion reaction rate coefficient, during neutral beam injection (NBI) and α-particle heating operations, are examined on the basis of the Boltzmann-Fokker-Planck (BFP) equations for deuteron, triton, beam ion and α-particle in deuterium-tritium (DT) thermonuclear plasmas.
1.The enhancement in the fraction of the NBI heating power deposited to ions becomes appreciable when beam-injection energy is larger than 1 MeV. For low temperatures, high densities and long confinement times, the slowing down of an energetic ion by NES is intensified, and thus the energetic components in beam-ion and α-particle velocity distribution functions are relatively small. In such a case, the NES effect on fractional energy deposition to ions is hardly to appear. On the contrary for low densities and short confinement times, the NES effect is significant. When n_e【greater than or equal】4×10^<19> m^<-3>, τ_E【greater than or equal】3 sec and T=20keV, the degree of the enhancement is almost 9(4) % for 1.5-MeV NBI (3.5MeV α-particle) heating.
2.Owing to the NES by fusion-produced α-particle knock-on tail is formed at 〜MeV energy range in fuel-ion distribution function. On the contrary, as a result of neutral-beam injection, 1〜2 orders large tail compared with those by α-particle appears in hundreds-keV energy range. The BFP calculation shows that the NES effect caused by injected beam on T(d,n)^4He reaction rate coefficient can be appreciable depending on plasma conditions. When P_<NBI>=20MW, E_<NBI>=1MeV,τ_E=3sec and T_e=20keV, the degree of the enhancement in T(d,n)^4He reaction rate coefficient reaches by about 7(3)% for n_e=2(4)×10^<19>m^<-3>.
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