SBIR Phase I: Microfabrication of Planar Accelerating Structures for High-Frequency Electron Linear Accelerators

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9661539 Yu This Small Business Innovation Research Phase I project will develop a planar structure for acceleration of a flat electron beam in a high-frequency, linear electron accelerator. The structure, different from the conventional cylindrically symmetric disk loaded structure, can be mass produced with modern microfabrication techniques using deep etch x-ray lithography. Phase I research will focus on the physics issues and fabrication techniques of the planar accelerating structure (PAS), and the feasibility of their application to future linear colliders and compact commercial linear accelerators operating at high frequencies. The PAS can be designed with a nearly constant axial electric field in the central region of the cavity through which the beam passes. Such a structure would reduce wakefields, and accommodate a high-current beam while maintaining a low current density. The PAS can also be used to accelerate electrons emitted by an asymmetric photoinjection gun, possibly eliminating the need of an expensive damping ring to control emittances. Asymmetric RF quadrupole beam focusing in a PAS-based linac is also possible. Precision microfabrication techniques are especially suitable for repeatable production of small, high-aspect ratio structures with tight tolerances. These techniques would replace tedious machining and brazing manufacturing processes for very small and intricate structures, and substantially reduce the manufacturing cost. If the research is successful, the resulting asymmetric planar accelerating structure (PAS) would be a revolutionary design applicable to a new generation of commercial linear accelerators and linear colliders. Microfabrication of PAS using lithography techniques will save production cost and increase precision in manufacturing tolerances. Microfabricated, PAS-based linacs can be used as compact medical and industrial accelerators. They can also be used as compact injectors to microfabricate free electron lasers to produce coherent, tunable radiations.