Compact and light weight x-ray sources that are man-portable and easily deployed in the field are very desirable for security and inspection as well as non-destructive testing purposes. X-ray energies of a few MeV are wells suited to penetrate most objects of interest for these applications. However, in some cases lower energies are more desirable where the objects may be less dense and or made of lower atomic number material given lower energies result in improved image contrast. This could further allow image subtraction and improved object identification. The ability for the x-ray source to be able to generate multiple energies especially within a single unit makes it a very attractive option. In Phase I of this proposal, we will investigate the feasibility of developing a variable energy linear accelerator system based on TibaRay technology that will produce at 2.5 MeV with the possibility of generating lower energies, with a dose rate of 5 R/min at 1 m and having a total system weight that is < 90 lbs. Our company, TibaRay Inc. is actively developing RF components including linacs for use in our novel medical accelerator application. These are based on recent technology developed at SLAC that involve new approaches to designing highly efficient resonant cavities and for manufacturing them. The proposed linac will be designed based on this concept of distributed coupling source. It will operate at X-band frequencies that area a standard for medical and industrial applications as well as for large research accelerators. It will be powered by a commercial RF source with the electrical power being provided by a power modulator based on a concept developed at TibaRay. This modulator will use the concept of distributed Marx capacitor bank where lower voltage modular units are stacked up as per requirement to generate the high voltage. In Phase I we plan to optimize all design aspect of the linac (beam energy, target and filtration material and thickness as well has size and weight). We will also evaluate the performance of the linac at 1 MeV and will simulate its behavior at lower energies to determine the performance limit. The thermal behavior of the device will be analyzed, and the cooling requirements will be considered. The RF power-modulator design will be optimized and evaluated for the different energy settings of the linac. Emphasis will be placed on compactness and weight of the system and manufacturing ease and reliability. This work will serve as the basis for Phase II where, if approved, we will develop these concepts into commercially available portable MeV x-ray sources. We will develop the plan for the production and sale of these devices.
