Richard A. Galloway

The use of dose and charge distributions in electron beam processing

Absorbed dose distributions in products treated with energetic electrons are influenced by the electron energy, the atomic composition of the material. the size and shape of the product and its orientation to the electron beam. Dose distributions can be measured by placing small dosimeters at various positions within some products, but more detailed data can be calculated with Monte Carlo codes that are readily available. For high-dose treatment processes, the magnitude and internal distribution of electrostatic charges may be significant. The accumulation of high charges could cause discharges through some materials, which could damage the products. This effect can be avoided by using electrons with sufficiently high energy, so that most of them will pass through the material. Charge distributions are difficult to measure, but they can be calculated with the Monte Carlo method. Dose and charge distributions with a wide range of electron energies in typical materials are presented in this paper. These have been obtained with the Integrated Tiger Series of Coupled Electron/Photon Monte Carlo Transport Codes (ITS). The data illustrate the effects of electron energy and material composition. These quantitative results will enable users to determine the electron energy beam current and beam power requirements for a variety of electron beam treatment processes

Rapid consolidation and curing of advanced composites using electron beam irradiation

A low-cost, low-waste manufacturing method for advanced thermoset composite parts could improve market penetration of composites compared to other engineering materials such as aluminum or steel. Such a method could combine some of the new trends in composites manufacturing such as resin infusion (eliminates need for prepreg), out-of-autoclave consolidation, and snap curing. The feasibility of a hybrid process with these characteristics has been demonstrated by uniting liquid composite molding, resin curing by electron beam irradiation, and high pressure consolidation with specialized elastomeric tooling. To demonstrate feasibility, a mold set was designed to make flat, square four-ply woven carbon fiber parts by (1) vacuum-infusing dry preforms with an electron beam–curable epoxy resin in minutes, (2) applying 690 kPa of uniform pressure and consolidating in seconds using an elastomer-faced specialized elastomeric tooling tool and simple hydraulic press, and (3) curing in seconds using a 3 MeV electron beam source. To better understand how various process parameters affect part performance, parameters are varied in a simple design of experiments, and flexural strength and stiffness, thickness distribution, fiber and void volume fractions, surface roughness, and cross-sectional characteristics (via microscopy) are measured and compared.

The IBA Easy‐E‐Beam™ Integrated Processing System

IBA Industrial Inc., (formerly known as Radiation Dynamics, Inc.) has been making high‐energy and medium‐energy, direct‐current proton and electron accelerators for research and industrial applications for many years. Some industrial applications of high‐power electron accelerators are the crosslinking of polymeric materials and products, such as the insulation on electrical wires, multi‐conductor cable jackets, heat‐shrinkable plastic tubing and film, plastic pipe, foam and pellets, the partial curing of rubber sheet for automobile tire components, and the sterilization of disposable medical devices. The curing (polymerization and crosslinking) of carbon and glass fiber‐reinforced composite plastic parts, the preservation of foods and the treatment of waste materials are attractive possibilities for future applications. With electron energies above 1.0 MeV, the radiation protection for operating personnel is usually provided by surrounding the accelerator facility with thick concrete walls. With lower en...

A new high-current proton accelerator

A high-current (>20 mA) dc proton accelerator is being developed for applications such as boron neutron capture therapy (BNCT) and the detection of explosive materials by nuclear resonance absorption (NRA) of gamma radiation. The high-voltage dc accelerator (adjustable between 1.4 and 2.8 MeV) will be a single-ended industrial Dynamitron/sup reg / system equipped with a compact high-current, microwave-driven proton source. A magnetic mass analyzer inserted between the ion source and the acceleration tube will select the protons and reject heavier ions. A sorption pump near the ion source will minimize the flow of neutral hydrogen gas into the acceleration tube. For BNCT, a lithium target for generating epithermal neutrons is being developed that will be capable of dissipating the high power (>40 kW) of the proton beam. For NRA, special targets will be used to generate gamma rays with suitable energies for exciting nuclides typically present in explosive materials. Proton accelerators with such high-current and high-power capabilities in this energy range have not been developed previously.