Several general approaches to remote servicing are briefly described for the LLL Field Reversed Mirror and Tandem Mirror Fusion reactors. Remote servicing system design considerations for the blanket module are briefly discussed. (RME)

Three magnetic confinement concepts, based on the mirror principle, are described. These mirror concepts are summarized as follows: (1) fusion-fission hybrid reactor, (2) tandem mirror reactor, and (3) reversed field mirror reactor. (MOW)

An examination of residual stresses and strains has been carried out experimentally on structural graphite components removed from Peach Bottom High-Temperature Gas-Cooled Reactor (HTGR) fuel elements. The purpose of this work is to confirm predicted stress distributions. Twenty-nine teledial fuel elements (of six- and eight-hole design) were irradiated in the Peach Bottom HTGR to fluences of less than or equal to 4 x 10/sup 25/ n/m/sup 2/ (E greater than 29 fJ) and time-average temperatures up to 1100/sup 0/C. The irradiation history was modeled with HTGR design codes. Performance predictions were verified by in-pile thermocouples and fuel burnup measurements. The predicted irradiation-induced strains were found to be in quantitative agreement with postirradiation measurements (less than or equal to 0.5 percent shrinkage over a 70-mm diameter). As a result of the temperature distribution in the teledial bodies, compressive stresses were predicted at the periphery and tensile stresses in the inner zones. A total of 19 graphite bodies from 8 different fuel elements were examined destructively for structural integrity and residual stresses.

A large cryogenic tensile test apparatus has been constructed at the Lawrence Livermore Laboratory (LLL) as part of the Nb/sub 3/Sn conductor program. This equipment was designed so that mechanical measurements can be made at 300, 77, or 4.2 K and critical current can be measured under simulated operating conditions as a function of the strain on large, prototype conductors for fusion magnets. The maximum operating parameters of the machine are load = 2.23 x 10/sup 5/ N, magnetic field = 12 T, and conductor current = 10 kA. Some of the unique features of this equipment are described and preliminary mechanical and superconducting data on sample Nb/sub 3/Sn conductors discussed.

The possibility of burning advanced fusion fuels in a tandem mirror is considered for a catalyzed DD cycle, in which the T and /sup 3/He reaction products from DD burn in both the solenoid and plugs are reinjected for complete burnup: 3D ..-->.. p + /sup 4/He + n + 21.6 MeV. Classical radial transport of the /sup 4/He ash determines the steady state alpha fraction in the solenoid. Synchrotron radiation losses are minimized at high beta, such that charged particle fusion power recovered in a direct converter exceeds radiation losses by a factor greater than two. An overall system Q = 4.5 is found for one reaction example but the power output is large (3 GE(e) net) due to the low power density in the solenoid. Optimizing recirculating power cost (Q) against plug/solenoid density ratio (power density) should result in much smaller reactor size and cost.

Papers are presented on research programs concerned with underground storage of radioactive wastes. A separate abstract was prepared for each of twenty-three papers. (JRD)

The laser acceleration of small (mass of order 1 gram) solid particles has been computationally analyzed. Acceleration is caused by a one sided laser illumination of a solid particle producing heating of the material, an ablation wave and the resulting ablative reaction force. Laser intensity is constrained to produce an ablation pressure less than the yield strength of the material (typically a few kbar). Preliminary results indicate the possibility of converting absorbed laser energy to solid density kinetic energy with an efficiency greater than 10 percent. Results of LASNEX calculations and comparison with an analytical model are presented which characterize the physics important to the process.

The formation of negative ions by hydrogen collisions on cesium-coated surfaces is discussed in the limiting cases where the resident cesium is either in the purely ionic state or in the purely atomic state. The survival fraction for negative ions moving away from a metal surface is calculated using a method employing complex eigenvalues. The fraction of surviving ions is found to be larger than calculated by previous workers. The secondary emission coefficient for negative ion production by incident atoms with energies of ten to one hundred electron volts is estimated to be in the range thirty to fifty percent. The secondary emission coefficient is found to be a sensitive function of the thickness of the alkali adsorbate coating for ion energies in the range below a few hundred electron volts.

Double shell targets for use with 0.2-1.0 ..mu.. lasers are discussed. With 0.2 ..mu.. light, such designs achieve 500-1000 times liquid density at 2 KJ, 10% or more of breakeven at 15 KJ, gains of 10 or more at 200 KJ and a gain of 1000 for lasers of 1 to 10 megajoules.

In multiwire proportional chambers used with honeycomb lead converters for detecting 511 KeV ..gamma.. rays from positron annihilation, a source of image blurring is generated by multiple interaction events due to the escape photoelectric x-ray or from the Compton scattered photon. Using the delay line readout method the majority of these double events are eliminated by using the fact that the sum of the time intervals from the prompt anode signal to the signal arrival at each end of the delay line is a constant to within the timing accuracy for a single interaction. Double interaction events produce a time sum which is shorter. Good improvement in image quality is obtained. The observed number of multiple events is larger than calculations would predict.

Preliminary experiments indicate that a hollow cathode, made from impregnated tungsten emitters, can be adapted for the Lawrence Berkeley Laboratory (LBL)/Lawrence Livermore Laboratory (LLL) ion source. Such cathodes could be the basis of a long life, continuously operated positive-ion source.

The spacial profile of a bunched or unbunched proton beam may be found by using a highly collimated molecular beam of N/sub 2/. A certain fraction of the molecular N/sub 2/ will be ionized as it crosses the proton beam. By measuring the N/sub 2//sup +/ current as a function of theta the cross section of the beam is directly obtained. As an example, a 10 A proton beam of diameter 1 mm is considered.

The Mirror Fusion Test Facility (MFTF) may be upgraded by extending the time of plasma sustenance in an approach to steady-state operation and/or by increasing the neutral-beam injection energy. Some parameter bounds for these upgrades are discussed as they relate to a definition of the required neutral-beam development.

A convenient method for determining the elastic constants of materials has been devised using the energy from a Q-switched neodymium-glass laser. Stress waves are induced in materials having circular rod or rectangular bar geometries by the absorption of energy from the laser. The wave transit times through the material are recorded with a piezoelectric transducer. Both dilatation and shear wave velocities are determined in a single test using an ultrasonic technique and these velocities are used to calculate the elastic constants of the material. A comparison of the constants determined for ten common engineering materials using this method is made with constants derived using the conventional ultrasonic pulse technique and agreement is shown to be about one percent in most cases. Effects of material geometry are discussed and surface damage to the material caused by laser energy absorption is shown.