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A deterministic forward model that includes the essential physics of all of the elements of the radiographic chain is required to extract volume density distributions and material interface surface positions from proton transmission radiographs by iterative non-linear fitting of parametric forward models. An essential part of the forward model is an analytic description of the angular distribution that an incident pencil beamlet acquires in passing through a thick slab of material. The angular-distribution model described here includes nuclear attenuation, multiple Coulomb scattering, coherent nuclear elastic scattering, and quasielastic nuclear scattering. The model is in good agreement with experimental step-wedge proton transmission data from experiments at the AGS proton accelerator at Brookhaven National Laboratory.

Multi-turn injection of H/sup -/ by foil stripping into an accumulator ring produces metastable neutrals that contribute to machine activation. Placing the foil in a magnetic field has been shown to greatly reduce such losses. However, the electrons associated with the H/sup -/ repeatedly and destructively pass through the foil under the influence of the magnetic field. The electrons can be swept off the foil by a small circular coil placed on surface of the injection dipole's pole face, centered on the electron's trajectory. The coil, in "magnetic-mirror" configuration, will exert a downward force on the electrons causing them to be swept off the foil, limiting the electron foil interactions to one or two. Beam dynamics simulations indicate that the effect on the stored beam is minimal and that such effects can be corrected by small correction magnets in the ring. As a test of this concept a full scale prototype has been fabricated and mapped in the "magnetic-mirror" configuration. The measured and calculated results were found to be in good agreement.

Performance requirements, design concepts, and test results for a prototype multipulse kicker modulator based on solid-state switches and a voltage-adding transformer topology are described. Tape-wound cores are stacked to form the transformer primary windings and a cylindrical pipe that passes through the circular inner diameters of the cores serves as the secondary winding of the step-up transformer. Boards containing MOSFET switches, trigger circuitry, and energy-storage capacitors plug into the core housings. A 50 kV prototype modulator that meets most of the facility requirements has been designed, fabricated, and tested at LLNL. More recent work has been concerned with designing and testing cores and boards with the full volt-second capability needed for 24-pulse operation. Results of the 50 kV prototype tests, preliminary tests of the full-volt-second cores and boards, and future development needs are described.

The ability to extract particle beam bunches from a ring accelerator in arbitrary order can greatly extend an accelerator's capabilities and applications. A prototype solid-state kicker pulser capable of generating asynchronous bursts of 50 kV pulses has been designed and tested into a 50 /spl Omega/ load. The pulser features fast rise and fall times and is capable of generating an arbitrary pattern of pulses with a maximum burst frequency exceeding 5 MHz. If required, the pulse-width of each pulse in the burst is independently adjustable. This kicker modulator uses multiple solid-state modules stacked in an inductive-adder configuration where the energy is switched into each section of the adder by a parallel array of MOSFETs. Test data, capabilities, and limitations of the prototype pulser are described.

An upgrade program for increasing the stored beam current in the proton storage ring is presently under way. A part of the upgrade is the design and installation of a four-magnet beam-bumping system used for phase-space painting and minimizing interaction of the stored beam with the injection stripper foil. This paper describes the bump-magnet system including the relevant beam requirements, magnet specifications, power-cable specifications, pulsed-modulator requirements, and beam-tube eddy-current effects. The magnets are ferrite window-frame magnets with saddle windings. Series-pass pulsed modulators are programmable both in rise and fall time as well as amplitude. The peak current can be varied between 50 and 300 A. Pulsed-current rise-time is fixed at 1 ms, and the linear fall-time during which the beam is injected into the ring can be varied between 0.5 and 1.5 ms.

In order to exploit the full potential of the Advanced Hydrotest Facility (AHF) facility to produce a time sequence of proton transmission radiographs throughout the dynamic event, a kicker/modulator for extraction from the 50 GeV ring that is capable of generating a string of 25 pulse pairs at arbitrary times within a total time duration of 100 microseconds or more is desired. The full range of desired pulse-train requirements cannot be met with the commonly used pulse-forming cables or networks (PFNs) switched with thyratrons. The preferred modulator design approach at present is a transformer voltage-adder concept with primary-side pulses formed with MOSFET-switched capacitors. This modulator will be a scale-up of an existing modulator that has been developed by Lawrence Livermore National Laboratory for use in DARHT, an electron induction accelerator facility at Los Alamos National Laboratory. Before the voltage-adder concept can be adopted for use in AHF, a working prototype that meets the AHF requirements for the pulse voltage, current, rise and fall time, and total pulse number must be built and tested. Additional requirements for pulse-to-pulse flattop height variation and baseline shift must also be met. A development and testing plan for the voltage-adder kicker modulator for AHF is described.

The Advanced Hydrotest Facility is to provide a time sequence of multiple radiographic images using a proton beam produced by a 50-GeV synchrotron. We give an overview of the approaches devised to produce up to twelve simultaneous radiographic images of an object by a sequence of beam-transport lines. The required distribution system has undergone a parametric study that optimized its configuration within operational constraints. These constraints and our approach to configuration optimization for both superconducting and normal-conducting transport lines are described. Additionally, we describe the optics stratagems that were devised to meet system requirements.

A survey of commercially available strain gauges potentially suitable for testing of superconducting magnets is presented. Strain measurement errors caused by magnetic fields and temperature changes are discussed. Previously unpublished data for the magnetic field induced error for weldable half-bridge strain gauges are given, along with the results of a test for the temperature dependence of the magnetorestistance of modified Karma alloy foil gauges in the liquid helium temperature range. Apparent strain-vs-temperature curves for the weldable half-bridge gauges and metal foil gauges are shown. Errors caused by magnetic fields are in general repeatable from gauge to gauge, whereas errors due to temperature effects exhibit considerable variation from gauge to gauge in a lot of nominally identical gauges.

The behaviour of some metal foil strain gauges in magnetic fields up to 6 T at room temperature and at the boiling points of nitrogen and helium has been investigated. At room temperature the Constantan alloy gauges showed a significant magnetically induced negative zero shift. Although at room temperature and liquid nitrogen temperature the Karma-type alloy gauges tested showed no observable magnetoresistance, they all showed a significant positive magnetoresistance at liquid helium temperature.

The magnet development effort for the controlled thermonuclear research program will require extensive testing of superconducting coils at various sizes from small-scale models to full-size prototypes. Extensive use of diagnostic instrumentation will be required and to make detailed comparisons of predicted and actual performance in magnet tests and to monitor the test facility for incipient failure modes. At later stages of the program, cryogenic instrumentation will be required to monitor magnet system performance in fusion power reactors. Measured quantities may include temperature, strain, deflection, coil resistance, helium coolant pressure and flow, current, voltages, etc. The test environment, which includes high magnetic fields (up to 8-10 T) and low temperature, makes many commercial measuring devices inoperative or at least inaccurate. In order to ensure reliable measurements, careful screening of commercial devices for performance in the test environment will be required. A survey of potentially applicable instrumentation is presented along with available information on operation in the test environment based on experimental data or on analysis of the physical characteristics of the device. Areas where further development work is needed are delineated.

Two types of heat sinks for cryogenic applications have been made with commercial technology. Both are described and analysed.