Lightweight electron accelerator cleans up

Using electron beams to sterilise materials and surfaces is a promising new technology - cleaner, safer and more environmentally-friendly than systems using gamma radiation and toxic gases. Where it falls down is the sheer size of the equipment needed - the accelerator tube needs to be around 2m long to accelerate the electrons up to the near-light speed required, and tubes this size weigh 500kg. However, Mitsubishi Heavy Industries has now developed an electron tube only a quarter as long as this, and a fraction of the weight.

The tube consists of many resonating cavities, each containing an electric field excited by a high-power microwave emitter. Electrons injected into these cavities are accelerated to an energy of 10 MeV. The microwave emitter is set at double the usual frequency used for this purpose, which is the key to the size reduction. The Mitsubishi tube is 50cm long, and weighs just 25kg.

The electron accelerator has already been used to sterilise surgical instruments and gowns, and the company plans to expand sales into other research and industrial areas during the next twelve months.