John H. Nuckolls

The feasibility of inertial‐confinement fusion

So concluded the chairman of a Department of Energy ad hoc committee of experts in 1979, after a comprehensive review of the US inertial‐confinement fusion program. In spite of this positive evaluation, the role of inertial‐confinement fusion in the total US energy program continues to be a subject of disagreement. Before I mention the issues of contention, let me describe inertial‐confinement fusion briefly. In a typical scheme, a pea‐sized target pellet containing hydrogen isotopes is projected into a reactor chamber, where it is suddenly irradiated with an intense beam of light or ions from a “driver” (see figure 1). As the surface of the target blasts away, the rocket‐like reaction forces implode the targets interior to densities and temperatures sufficient to cause the hydrogen nuclei to fuse, releasing an amount of energy equivalent to that of a barrel of oil (see PHYSICS TODAY, August 1973, page 46).

Laser‐induced thermonuclear fusion

Laser‐induced fusion has recently joined magnetic‐confinement fusion as a prime prospect for generating controlled thermonuclear power. During the past three years, the Atomic Energy Commission has accelerated the national laser‐fusion program more than tenfold, to about

Laser-Induced Implosion and Thermonuclear Burn

30 million annually, and the Soviet Union has a program of comparable size.

An Alternative Thermonuclear n-Capture Path to the Superheavy Island'

In high density laser induced fusion, the key idea is laser implosion of hydrogen isotope microspheres to approximately 10,000 times liquid density in order to initiate efficient thermonuclear burningl. Fusion yields 50–100 times larger than the laser energy for laser energies of 105–106 joules have been achieved in sophisticated computer simulation calculations. Most of the dense pellet is isentropically compressed to a high density Fermi-degenerate state, while thermonuclear burn is initiated in the central region. A thermonuclear burn front propagates radially outward from the central region heating and igniting the dense fuel.

The Development of Nuclear Explosives

Thermonuclear neutron-capture approaches to heavy transuranium element synthesis are investigated. Certain feature of capture experiments using thermonuclear macro-explosives are re-analyzed in view of recent results of nuclear shell-structure theory and theoretical developments in laser-energized fusion micro-explosions. The micro-explosion conditions for prompt multiple neutron capture are estimated for the simplest moderation techniques. We speculate on some practical neutor-capture paths to the superheavy island, especially a hybrid approach, using both macro-and micro-explosion events.

New approaches to CTR: general relativistic power plants

The development of nuclear explosives by the United States and their embedding in nuclear weapons systems has proceeded through several basic phases, most of which in turn have several well-defined sub-epochs. We review these to the extent possible under present circumstances from the perspective of Edward Teller’s impact on mid-twentieth century history.

Outlook for inertial confinement fusion

The use of small black holes (SBH) for producing controlled fusion power is described. The detection of SBH and power production from them are discussed. Energy conversion and transmission are mentioned. (MOW)

Inertial Confinement Fusion

During the next ten years the National Ignition Facility (NIF) will be completed and substantial fusion gains are likely to be achieved with the NIF megajoule class solid state laser. A facility very similar to NIF is being constructed by the French nuclear weapons program. Technological advances promise to make ICF increasingly attractive as a practical energy source. These advances include very high gain targets (e.g., the fast ignitor), petawatt lasers, diode pumped solid state lasers, and advanced heavy ion accelerators. Beyond the next ten years an experimental inertial fusion (IF) reactor will be needed to take the major step from NIF to a practical fusion power plant. A key question: how is this IF experimental reactor to be funded? A 100 MWe scale IF reactor could produce several kilograms per year of low cost tritium for DOE Defense Programs. Tritium produced by competing fission reactor and accelerator/spallation options is estimated to cost more than one hundred million dollars per kilogram, much more than the cost of tritium produced by a fusion reactor. Tritium production provides a defense funded option for IF`s next step beyond NIF.

Prospects for developing attractive magnetic fusion concepts

Edward Teller has been a strong proponent of harnessing nuclear explosions for peaceful purposes. There are two approaches: Plowshare, which utilizes macro-explosions, and inertial confinement fusion, which utilizes micro-explosions. The development of practical fusion power plants is a principal goal of the inertial program.

Laser Compression of Matter to Super-High Densities: Thermonuclear (CTR) Applications

Comments are made pertaining to a generic magnetic fusion reactor study carried out at ORNL. A second study was made of the required reactor characteristics for attractive fusion reactors. The study concluded that both the physics and economics would be achievable with present magnetic configurations.