Updated Nucleosynthesis Constraints on Unstable Relic Particles

We revisit the upper limits on the abundance of unstable massive relic particles provided by the success of Big-Bang Nucleosynthesis calculations. We use the cosmic microwave background data to constrain the baryon-to-photon ratio, and incorporate an extensively updated compilation of cross sections into a new calculation of the network of reactions induced by electromagnetic showers that create and destroy the light elements deuterium, he3, he4, li6 and li7. We derive analytic approximations that complement and check the full numerical calculations. Considerations of the abundances of he4 and li6 exclude exceptional regions of parameter space that would otherwise have been permitted by deuterium alone. We illustrate our results by applying them to massive gravitinos. If they weigh ~100 GeV, their primordial abundance should have been below about 10^{-13} of the total entropy. This would imply an upper limit on the reheating temperature of a few times 10^7 GeV, which could be a potential difficulty for some models of inflation. We discuss possible ways of evading this problem.Comment: 40 pages LaTeX, 18 eps figure

Physics problems of thermonuclear reactors

From topical conference on energy; Philadelphia, Pennsylvania, USA (Nov 1973). A problem common to all controlled fusion reactors is that of the burning deuterium --tritium fuel under conditions of plasma confinement which approach the ideal limit as nearly as possible. After ignitlon, the balance between alpha- particle energy deposition and plasma losses (radiation plus thermal and particle diffusion) determines the stability or instability of the burn in toroidal systems. Tokamak systems are described both with unstable, injection-regulated burn cycles and stabilized steady-state burn conditions. In the theta-pinch reactor an unstable burn occurs, some, what regulated by high-beta plasma expansion, which is quenched by a programmed plasma decompression. The plasma expansion during the constant-pressure burn provides direct'' conversion of plasma thermonuclear heat to electrical output, in addition to the electrical power derived from the neutron energy through conventional thermal conversion equipment. The open-ended mirror reactor is characterized by a direct conversion system for recovering end-loss plasma energy and converting it to electrical energy for reinjection into the plasma. This allows a favorable reactor energy balance and an amplification factor Q (= thermonuclear energy output/injected plasma energy) which is compatible with classical collisional losses. For the three reactor types considered the ramifications of burn and confinement conditions for reactor configuration, energy balance, economy, fuel handling, materials problems, and environmentalradiological factors are considered. (auth

Fusion reactors as future energy sources

From conference on energy policies and the international system; New, Delhi, India (4 Dec 1973). The need is now apparent for a global energy policy with the following characteristics: Compatibility with environmental and economic factors; large fuel resources, the recovery and exploration of which have minimal environmental impact and which do not introduce disturbing factors into the world political situation. Fusion power in this context is discussed, including assessments of its potential and of the problems yet to be solved in achieving its realization. The proposition is advanced that fusion should be considered as the ultimate source of energy, and that other sources of energy, including conventional nuclear power, should be considered as interim sources. (auth

Possible application of electromagnetic guns to impact fusion

The rail gun has the potential of developing into an impact fusion macroparticle accelerator, and it is the most promising electrical accelerating system since its efficiency can be high, its length relatively short, and there is a considerable body of experimental work. The next step in rail gun development would be to increase the velocity by a factor of three or four using three to five gram pellets. The final goal of rail gun research and development would then be to increase the velocity by another factor of five to six to obtain impact fusion parameters

Project management of scyllac construction

From fifth symposium on engineering problems of fusion research; Princeton, New Jersey, USA (6 Nov 1973). Scyllac, a 10-MJ ( approximates 10 million) toroidal theta-pinch experiment, was authorized by Congress in 1968 and the first plasma experiments began in 1971. The procedures used to establish and maintain communication between the physicists, the engineers and the installation personnel in the design and construction of the experiment are described. (auth

Surface effects at the first-wall of the Reference Theta-Pinch Reactor (RTPR)

From surface effects in controlled thermonuclear fusion devices and reactors meeting; Argonne, Illinois, USA (10 Jan 1974). The fundamental operating principles and parameters inherent to the Reference Theta-Pinch Reactor (RTPR) are described herein. An emphasis is placed on those engineering aspects of the RTPR design which bear directly on the thermal, hydraulic, and radiation response of the first wall. The major portion of the data presented is calculational, and further experimental and theoretical results are needed to assess accurately anticipated material problems and to forecast appropriate solutions. Material problems envisioned for the RTPR first wall are discussed brie fly in the context of the particular RTPR design described. (auth

Pulsed Energy Storage in Fusion Devices

Research and development on pulsed energy technologies primarily for pulsed high-beta fusion systems, is described. Systems studies at Los Alamos and elsewhere have served to define these required technologies, which include fast discharging homopolar machines, pulsed superconducting coils, and the associated switching technology. Programs at the Los Alamos Scientific Laboratory, Westinghouse, and The University of' Texas are described here.Center for Electromechanic