Sano Takayoshi, Fujioka Shinsuke, Mori Yoshitaka, Mima Kunioki, Sentoku Yasuhiko
Institute of Laser Engineering, Osaka University, Suita, Osaka 565-0871, Japan.
The Graduate School for the Creation of New Photonics Industries, Hamamatsu, Shizuoka 431-1202, Japan.
Phys Rev E. 2020 Jan;101(1-1):013206. doi: 10.1103/PhysRevE.101.013206.
Thermal fusion plasmas initiated by standing whistler waves are investigated numerically by two- and one-dimensional particle-in-cell simulations. When a standing whistler wave collapses due to the wave breaking of ion plasma waves, the energy of the electromagnetic waves transfers directly to the ion kinetic energy. Here we find that ion heating by use of standing whistler waves is operational even in multidimensional simulations of multi-ion species targets, such as deuterium-tritium (DT) ices and solid ammonia borane (H_{6}BN). The energy conversion efficiency to ions becomes as high as 15% of the injected laser energy, which depends significantly on the target thickness and laser pulse duration. The ion temperature could reach a few tens of keV or much higher if appropriate laser-plasma conditions are selected. DT fusion plasmas generated by this method must be useful as efficient neutron sources. Our numerical simulations suggest that the neutron generation efficiency exceeds 10^{9} n/J per steradian, which is beyond the current achievements of the state-of-the-art laser experiments. Standing whistler-wave heating would expand the experimental possibility for an alternative ignition design of magnetically confined laser fusion and also for more difficult fusion reactions, including the aneutronic proton-boron reaction.
通过二维和一维粒子模拟对由驻波哨声波引发的热核聚变等离子体进行了数值研究。当驻波哨声波由于离子等离子体波的波破裂而坍塌时，电磁波的能量直接转移到离子动能上。在此我们发现，即使在多离子种类靶标的多维模拟中，例如氘 - 氚（DT）冰和固态氨硼烷（H₆BN），利用驻波哨声波进行离子加热也是可行的。离子的能量转换效率高达注入激光能量的15%，这在很大程度上取决于靶标厚度和激光脉冲持续时间。如果选择合适的激光 - 等离子体条件，离子温度可达几十keV甚至更高。通过这种方法产生的DT聚变等离子体必定可作为高效中子源。我们的数值模拟表明，中子产生效率超过每球面度10⁹ n/J，这超出了当前最先进激光实验的成果。驻波哨声波加热将拓展磁约束激光聚变替代点火设计以及更困难聚变反应（包括无中子质子 - 硼反应）的实验可能性。
