Impact ignition as a track to laser fusion

Abstract

In impact ignition, the compressed deuterium–tritium main fuel is ignited by impact with a separately imploded portion of fuel, which is accelerated in a hollow conical target to hyperspeeds of the order of 1000 km s−1. Its kinetic energy is directly converted into thermal energy corresponding to an ignition temperature of about 5 keV upon collision with the compressed fuel. The ignitor shell is irradiated by nanosecond pulses at intensities of between 1015 and 1016 W cm−2 with a wavelength of 0.25–0.35 µm, resulting in ablation pressures of several hundred mega-bars. Hydrodynamics-dominated physics and avoidance of ultra-intense petawatt lasers are notable features of this scheme. Experimental results for velocities exceeding 1000 km s−1, ion temperatures up to 3 keV, and neutron yield increases of 100-fold due to the impact effect indicate the potential of impact ignition for fusion energy production. The overall performance of impact ignition is reviewed with new analyses on the neutron yield and shell acceleration.

The convergence of the shock wave in the presence of energy release

“…Настоящая работа была стимулирована анализом расчетов [15][16], связанных с возбуждением термоядерного горения в однородно сжатом шаре (мишень лазерного термоядерного синтеза) путем удара по внешней его поверхности ускоренной (до 1000 км/с) макрочастицы (т.н. «ударный синтез», Impact Fusion).…”

“…Исходные для настоящего рассмотрения работы [15,16] относятся к другой ситуации. Здесь начальное энерговыделение также происходит в малом (по сравнению со всем рассматриваемым веществом) объеме, но в узком приповерхностном слое шара.…”

“…Результаты вычислительных экспериментов, проведенных в настоящей работе, говорят о следующем. Внутренняя часть рассмотренной здесь мишени (с температурой 0 ) практически «не горит» по сравнению с энерговыделением во внешнем узком слое с температурой G , что отвечает условиям постановок [15,16]. Формальное отношение времен обострения (14) внутренней и внешней области оказывается во всех наших расчетах в диапазоне 10 G − 10 0{ .…”

A high temporal resolution numerical algorithm for shock wave velocity diagnosis

“…Particularly in inertial confinement fusion (ICF), the generation of shock waves in ablation is a high-speed passing process 9,10 . The entire process of propagation, reflection, attenuation, and disappearance only takes several nanoseconds or even picoseconds 11,12 . The driven asymmetry and fluid mechanics instability, which are the cause of compression insufficiency, can be reflected by the record of the shock wave 13–15 .…”

Effects of relativistic electron temperature on parametric instabilities for intense laser propagation in underdense plasma

“…The propagation of short intense lasers in underdense plasma has been intensively studied, since it is closely related to a number of applications such as laser-driven particle acceleration 1 , advanced concept of inertial confined fusion including fast ignition with electron or ion beams [2][3][4] , shock ignition 5 , impact ignition 6 , and so on. Earlier studies 7 on short-pulse laser plasma interactions are mostly based on the cold plasma model assuming that the plasma electrons cannot be heated to high temperature by short pulse lasers in a short interval of time.…”