An Advanced Analysis Tool for Predicting Parasitic Oscillations in High Power Klystrons Used in Particle Colliders

72893S03-I High-cost klystrons are important components of proposed new accelerators such as the NLC. Highly accurate and detailed electromagnetic analyses are needed to fully understand and mitigate some of the effects that precede tube failure, such as instabilities due to high-order mode generation. These analyses can be accomplished only by using sophisticated frequency-domain, time-domain, and particle-in-cell analysis codes that run on massively parallel computers. They also must be easy to use and tightly integrated with geometry creation, automated meshing, post-processing, and optimization capabilities. This project will create an analysis module, specifically targeted for understanding parasitic oscillations in klystrons, that integrates parallel eigenmode, time-domain, and particle-in-cell analysis capabilities within a commercial design framework. The package will help identify modes that lead to parasitic oscillations, and ultimately will support the design of damping schemes to eliminate the oscillations. A prototype version of the klystron analysis module will be developed in Phase I, with an emphasis on identification of problematic high-order modes. This will involve the development of user-interface support for electrostatic particle-in-cell capabilities, and an automated system for identifying and classifying potentially unstable modes. Commercial Applications and Other Benefits as described by awardee: More robust designs for very high-power klystrons should help reduce the construction and operation costs for high-energy particle colliders used by the physics community. Klystrons also are used in a variety of commercial and military applications, including microwave telecommunications, radar, remote sensing, industrial heating/drying, and commercial accelerators for medical and other purposes.