INEXPENSIVE BRAZELESS MEDICAL ACCELERATOR

The cost of the accelerating waveguide in modern medical accelerators and industrial linacs is substantial. This comes to no surprise, as the accelerating waveguide is a set of diamond – turned copper resonators brazed together. Such a multistep manufacturing process is not only expensive, but also prone to manufacturing errors, which decrease the production yield. In the big picture, the cost of the accelerating waveguide precludes the use of accelerators as a replacement option for radioactive sources. This is especially true for systems intended for operation in an environment with electricity, temperature, humidity, and water supply issues. Ultimately, an inexpensive and robust accelerator is needed. Euclid Techlabs LLC proposes a revolutionary brazeless accelerating structure made out of copper-plated stainless steel or tungsten cells, with copper irises serving as gaskets for vacuum and RF seals. Skipping the brazing step and using stainless steel components reduces the costs compared to copper. Because of a higher radiation screening efficiency for stainless steel or tungsten, the shielding weight is also reduced. Brazeless design allows the addition of cooling channels and embedded focusing magnets for performance optimization. Embedded focusing/steering elements allow for a small bore, lower current focusing coil for a significant weight and space reduction. In Phase I we designed and fabricated a full-featured brazeless accelerating structure with microwave coupler. Field balance tuning was first demonstrated in a low power test. Then a vacuum test was performed, followed by high power testing (conditioning) of the structure. The structure was conditioned to a 10 MV/m gradient. There was no damage observed to the copper-plated surfaces, and minor multipactor-related damage was found on structure irises. This was the shortest turnaround time for a high power microwave R&D effort on the smallest budget in our 15 years of experience. In Phase II, we will produce and test several designs for a few MeV accelerator based on this brazeless design approach. A field-emission or thermal electron gun will be incorporated into the design. The ultimate goal is to produce a very inexpensive few MeV electron accelerator. Besides high power tests at our R&D facility in Bolingbrook, IL, we plan to perform an ultra-high power test at the Stanford Linear Accelerator Center. The high gradient accelerator community may also benefit from the fast turnaround testing of various materials and geometries based on this brazeless design. Commercial Applications and Other Benefits: Besides the industrial application, this robust and inexpensive accelerator will find application as a replacement for radioactive isotopes for use as an irradiation source. Due to increased regulations imposed by US Nuclear Regulatory Commission (NRC), there are additional indirect expenses associated with radionuclide-based sources. These expenses are associated with the disposal of the radionuclide source of the irradiator. The proposed inexpensive design makes radiation-on-demand accelerator–based gamma ray sources commercially viable.