The Tandem Mirror Experiment Upgrade (TMX Upgrade) vacuum system uses most of the vacuum system from the original TMX and substantially increases its capabilities. The vacuum system provides the main structure for the experimental apparatus, as well as providing and maintaining the vacuum environment. The vacuum vessel provides the structure supporting all magnets, as they are contained inside the vacuum vessel, all of the neutral-beam injectors, and the various diagnostics. The vessel provides the main vacuum enclosure and the various access ports required by the magnet system, injector system, internal vacuum system, and plasma diagnostics. The vacuum environment is created and maintained by two systems, the external vacuum system and the internal vacuum system. The external system consists of mechanical pumps, turbopumps, and cryopumps, and creates a vacuum inside the vessel down to a minimum pressure of 10/sup -6/ Torr. The internal vacuum system further reduces the pressure into the 10/sup -8/ Torr range and provides the fast pumping required to handle the excess gas from the neutral-beam injector system during a plasma shot. The internal vacuum system consists of titanium sublimators and liquid nitrogen (LN) liners that separate the vacuum vessel into various pumping regions.

Instabilities with frequencies in the neighborhood of the electron cyclotron frequency are of interest in determining stable operating regimes of hot-electron plasmas in EBT devices and in tandem mirrors. Previous work used model distributions significantly different than those suggested by recent Fokker-Planck studies. We use much more realistic model distributions in a computer code that solves the full electromagnetic dispersion relation governing longitudinal and transverse waves in a uniform plasma. We allow for an arbitrary direction of wave propagation. Results for the whistler and upper-hybrid loss-cone instabilities are presented.

We have determined experimentally the fraction of laser light incident on DT filled cryogenic polymer coated and bare glass microsphere targets that is absorbed to produce target heating. Data have been obtained for bare glass and CH and CF polymer coated microspheres at 488 nm and 632 nm laser wavelengths. The measurement technique used and experimental results obtained are presented.

A magnet set, consisting of 24 coils, has been designed for the TMX Upgrade. Like the coil set designed for the TMX experiment, the coils for TMX Upgrade consist of a central-cell set with a minimum-B plug set on each end. Between the central cell and each end plug, there is a flux bundle recircularizing transition set. Physics considerations require that the TMX Upgrade magnet set be almost twice as long as the TMX magnet set (14 m between the outer mirrors). The central circular coils are the only coils used from TMX. The TMX transition set of two C-coils and an octupole is replaced by a C-coil and an Ioffe coil. The TMX plug composed of a baseball coil and two C-coils is replaced by an Ioffe coil, two C-coils and two circular coils. A comparison between the TMX and TMX Upgrade magnet sets is shown.

A heavy ion beam propagating through a hard or near vacuum (< 10/sup -3/ torr) is subject to emittance growth due to the phase space distortions caused by anharmonic self-forces. If the distortion remains uncorrected, an enlarged focal spot results. Analytic predictions of an increase in rms emittance and focal spot size are given for the hard vacuum case and are shown to agree with computer simuations for initially cold beams. Some effects of the beam preconditioning in the region from accelerator output to final focusing magnet are discussed. For the case of near vacuum transport (10/sup -4/ to 10/sup -3/ torr), prediction of final focal spot size requires consideration of additional effects such as beam stripping to high charge state and charge neutralization by electrons which are produced internally in the vessel and/or are injected from outside.

Measurement of inertial-fusion targets has stimulated the development of many new techniques and instruments. This paper reviews the basis for selected target measurement requirements and the development of optical interferometry, optical scattering, microradiography and scanning electron microscopy as applied to target measurement. We summarize the resolution and speed which have been achieved to date, and describe several systems in which these are traded off to fill specific measurement applications. We point out the extent to which present capabilities meet the requirements for target measurement and the key problems which remain to be solved.