Hand-Portable Accelerator for Radioisotope Replacement in Field Radiography

Portable X-ray sources are widely used by security, nuclear safeguard, and defense agencies. However, currently employed sources have significant drawbacks, limiting their practical applications. For example, radioisotope-based gamma sources have many associated safety and security issues. Betatrons have very low-dose emission due to low duty cycle, and non-ideal SWaP characteristics, making them unpractical for many field operations. X-ray tubes operating in the range of 150 - 370 keV have such operational as a limited range of energy variability, and non-variable dose rates or repetition rates. RadiaBeam is developing a hand-portable 50 lbs X-ray source based on a Ku-band electron linac. The dramatic level of miniaturization and cost-reduction is achieved thanks to the implementation of such innovative technologies as air-cooled Ku-band air-traffic control magnetrons, split accelerating structure fabrication technology, and solid-state Marx modulators. This innovative but at the same time very practical approach allowed to bring the size, weight and cost of low energy linacs to the point where they can be easily man-portable, while adding the capability to adjust radiation parameters (energy, dose rep. rate), thus replacing X-ray tubes and radioisotopes in critical field radiography applications. In Phase I, we have designed a high-voltage Marx modulator, achieving rise/fall times of as short as 50 ns, and a weight of ~1.2 kg. We have also demonstrated the stand-alone operation of the modulator from 2 standard Li-Ion batteries, which should provide a full power operation for at least 15 minutes. We have designed two versions of the accelerating structures, powered by the same 250 kW Ku-band magnetron: high-energy 2 MeV version, and low-energy fully adjustable 150-370 keV version. A prototype structure was fabricated and measured. In Phase II, we will build the full prototype of the 150-370 keV linac and demonstrate its performance with real radiographic imaging tests. The full system will include the RF source, accelerating structure, brand new electron gun, high voltage modulator, vacuum system, cooling fans, X-ray converter and enclosure box. The goal of his project is to build an ultra-compact portable radioactive material-free source of X-rays that will be used for the applications including physical security, inspection for munitions and defects, nuclear explosives investigations, explosives disposal, aircraft inspection, verification and characterization of nuclear fuel and materials, as well as pipelines, high-voltage conduits, turbines and jet engines NDT.