The technology base formed by the development of high peak power simulators, laser drivers, free electron lasers (FEL's), and Inertial Confinement Fusion (ICF) drivers from the early 60's through the late 80's is being extended to high average power short-pulse machines with the capabilities of performing new roles in environmental cleanup applications and in supporting new types of industrial manufacturing processes. Some of these processes will require very high average beam power levels of hundreds of kilowatts to perhaps megawatts. In this paper we briefly discuss new technology capabilities and then concentrate on specific application areas that may benefit from the high specific energies and high average powers attainable with short-pulse machines. 011O5 1993 DtSTBIBU'I'ION OF THIS L._,..:I C,UME:NT IS UNLIMIFED OSTI ¢ ! such as the use of ethylene oxide or methyl bromide, which may, in turn, make accelerator treatment methods more appealing. To gain acceptance, the technology must be shown to offer a robust and cost effective solution to a specific need.

We review research investigating the application of intense pulsed ion beams (IPIBs) for the surface treatment and coating of materials. The short range (0.1–10 μm) and high-energy density (1–50 J/cm2) of these short-pulsed (⩽1 μs) beams (with ion currents I=5–50 kA, and energies E=100–1000 keV) make them ideal in flash heating a target surface, similar to the more familiar pulsed laser processes. IPIB surface treatment induces rapid melt and solidification at up to 1010 K/s causing amorphous layer formation and the producing nonequilibrium microstructures. At higher energy density the target surface is vaporized, and the ablated vapor is condensed as coatings onto adjacent substrates or as nanophase powders. Progress towards the development of robust, high-repetition rate IPIB accelerators is presented.

The emerging capability to produce high average power (10-300 kW) pulsed ion beams at 0. Deposition of the energy in a thin surface layer allows melting of the layer with relatively small energies (1-10 J/cm2) and allows rapid cooling ofthe melted layer by thermal conduction into the underlying substrate. Typical cooling rates of this process (109 Wsec) are sufficient to cause amorphous layer formation and the production of non-equilibrium microstructures (nanocrystalline and metastable phases). Results fiom initial experiments confirm surface hardening, amorphous layer and nanocrystaline grain size formation, corrosion resistance in stainless steel and aluminum, metal surface polishing, controlled melt of ceramic surfaces, and surface cleaning and oxide layer removal as well as surface ablation and redeposition. These results follow other encouraging results obtained previously in Russia using single pulse ion beam systems.Potential commercialization of this surface treatment capability is made possible by the combination of two new technologies, a new repetitive high energy pulsed power capability (0.2-2MV, 25-50 kA, 60 ns, 120 Hz) developed at SNL, and a new repetitive ion beam system developed at Cornell University.

Electrical breakdown across a vacuum/plastic interface in the presence of applied or self-generated magnetic fields, B?3.5 T, was investigated. The E×B drift of charged particles near the interface in these experiments was away from the insulator surface. The self-magnetic field effects on a plastic vacuum insulator flashover were examined with inductive loads, particle beam loads, and imploding plasma loads. Average breakdown electric fields of up to 38 MV/m were observed. Power densities of 100 TW/m2 were passed through acrylic-vacuum interfaces. The flashover electric fields were improved over the B = 0 fields from previous experiments by factors of 7.1, 5.0, and 1.8 for the −45°, 0°, and +45° insulators, respectively.

Single-pulse pulsed power systems were developed during the 60's through the late 80's for a variety of applications such as EMP and x-ray pulse simulators, free electron laser drivers, and high-power microwave sources. The addition of repetitive pulsed power capabilities to some of the specialized output devices developed for these programs can create systems that address areas of current public concern in environmental cleanup and enhanced manufacturing technology. These systems can produce non-thermal, in-depth, pulsed energy deposition or energy coupling into the material through pulsed radiated fields.Non-thermal destruction of organic contaminants using the free radicals produced by e-beam interactions has been demonstrated in simulated mixed-waste radiolyzed material. Cleanup of organic contaminants in ground waters can also be accomplished using e-beams. Both applications require beams with 100's of kW average power with beam energies of about 10 MeV. High power is required for high volume throughput, or to achieve the required dose, and high beam energy is required for uniform energy deposition profiles.Pulsed power driven ion sources can effectively couple to large surface areas to achieve amorphous layer formation, formation of surface alloys, and surface hardening. Ceramics and carbon composites may be candidates for e-beam treatment and bonding where energy is delivered to a high-z interlayer. High energy shortpulse electron beams may also play a role in the welding of large, thick-section, assemblies in a non-vacuum environment.High average power systems, based on saturable magnetic switching, are now entering the operational phase at several facilities. Such systems can provide small area or large area beams as demanded by the specific application. These operational facilities, coupled with single pulse accelerators, can be used in an application development process to acquire feasibility demonstration data and to develop the necessary interdisciplinary teams with pulsed power, materials processing, medical effects, and radiochemistry experience. NM 87 185 * Experiments have been performed on Sandia's PBFA II accelerator using a thin film LiF source studying power and energy coupling to a lithium ion diode, ion divergence, and optimal focusing of the lithium beam to enable target experiments. These experiments have provided insight into the present limitations on focussed ion intensity in single-stage applied-B ion diodes using a passive ion source.Power and energy coupling to the ion beam is primarily limited by "parallel loads" in the diode and in the Magnetically Insulated Transmission Lines (MITLs) that feed the power from the accelerator to the ion diode. The losses in the M m s are due to electron flow that lowers the flow-impedance of the line. This problem may be alleviated by modifying the design of the vacuum section of PBFA II to minimize injection of electrons into the MITLs. The parallel load in the diode is hypothesized to be caused by chargeexchange neutrals generated by the primary ...