Inertial confinement fusion (ICF) is an approach to fusion that relies on the inertia of the fuel mass to provide confinement. To achieve conditions under which inertial confinement is sufficient for efficient thermonuclear burn, a capsule (generally a spherical shell) containing thermonuclear fuel is compressed in an implosion process to conditions of high density and temperature. ICF capsules rely on either electron conduction (direct drive) or x rays (indirect drive) for energy transport to drive an implosion. In direct drive, the laser beams (or charged particle beams) are aimed directly at a target. The laser energy is transferred to electrons by means of inverse bremsstrahlung or a variety of plasma collective processes. In indirect drive, the driver energy (from laser beams or ion beams) is first absorbed in a high‐Z enclosure (a hohlraum), which surrounds the capsule. The material heated by the driver emits x rays, which drive the capsule implosion. For optimally designed targets, 70%–80% of the d...

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Development of the indirect‐drive approach to inertial confinement fusion and the target physics basis for ignition and gain

The 1990 National Academy of Science final report of its review of the Inertial Confinement Fusion Program recommended completion of a series of target physics objectives on the 10-beam Nova laser at the Lawrence Livermore National Laboratory as the highest-priority prerequisite for proceeding with construction of an ignition-scale laser facility, now called the National Ignition Facility (NIF). These objectives were chosen to demonstrate that there was sufficient understanding of the physics of ignition targets that the laser requirements for laboratory ignition could be accurately specified. This research on Nova, as well as additional research on the Omega laser at the University of Rochester, is the subject of this review. The objectives of the U.S. indirect-drive target physics program have been to experimentally demonstrate and predictively model hohlraum characteristics, as well as capsule performance in targets that have been scaled in key physics variables from NIF targets. To address the hohlrau...

The physics basis for ignition using indirect-drive targets on the National Ignition Facility

As the way of decreasing of the driver energy which is needed for ignition of the LCF targets, the conception of separation of the process of compression of the main mass of the fuel and the process of heating of the ignitor is suggested. Thermonuclear gain of the target with direct heating of the ignitor is calculated. It's shown that using the target with direct heating of the ignitor may lead to considerable decreasing of the driver energy: in (10–20) times for “breakeven,” and in (5–10) times for thermonuclear gain of 100–300 in comparison with the traditional conception of simultaneous compression and heating of the ICF target.

Thermonuclear gain of ICF targets with direct heating of ignitor

Inertial confinement fusion, based on laser-heating a deuterium–tritium mixture, is one of the approaches towards energy production from fusion reactions. Now, record energy-yield experiments are reported—bringing us closer to ignition conditions.

Inertially confined fusion plasmas dominated by alpha-particle self-heating

It is shown that a relatively weak initial shock introduced into an otherwise isentropic hollowshell implosion can cause central fuel ignition, the bulk of the fuel undergoing little increase in entropy. The imploded-state fuel configuration is analysed at the threshold of ignition, and it is found that electron heat conduction is the predominant cooling mechanism opposing fuel ignition. Approximate temperature-dependent ρR requirements are presented for the conduction-limited ignition of thin DT shells, and for the equality of electron heat conduction and α-particle transport in thermonuclear burn propagation.

https://iopscience.iop.org/article/10.1088/0029-5515/19/2/006/pdf

Laser-driven isentropic hollow-shell implosions: the problem of ignition

The process of non-uniform laser-driven DT plasma burning caused by the thermonuclear burn wave produced and propagating in plasma is investigated theoretically. The energy transfer from the burning plasma region to the remaining cold portion is assumed to be realized either by α-particles or by free electrons. A similarity solution of this problem has been obtained and, deriving from this solution, the conditions for "firing-up" non-uniform thermonuclear targets are defined.

S.Yu. Gus'kov

Papers

Similarity solution of thermonuclear burn wave with electron and α-conductivities

Possibility of determining the characteristics of laser plasma by measuring the neutrons of the DT reaction