Design of collinear load for S-band compact electron LINAC

This paper describes a design of a four-cavity collinear load for a compact electron LINAC. The collinear load is composed of four cavities which are coated by high-resistance material of FeSiAl. In order to get the performance parameters of the material for designing the load, this paper advances in a novel method which combines a testing and simulation. According to these parameters, the four-cavity collinear load is designed, manufactured and finally revised. Test results and running in a LINAC of 14 MeV show that the collinear load works well. Keywords: Collinear load, FeSiAl, Frequency shift, Fitting revisin

rf conditioning and breakdown analysis of a traveling wave linac with collinear load cells

Huazhong University of Science and Technology (HUST) has built a compact linac-based terahertz free electron laser (THz-FEL) prototype. In order to achieve compact structure, the linac uses collinear load cells instead of conventional output coupler to absorb remanent power at the end of linac. The new designed structure is confronted with rf breakdown problem after a long time conditioning process, so we tried to figure out the breakdown site in the linac. Without transmitted signal, we propose two methods to analyze the breakdown site mainly based on the forward and the reflected power signals. One method focuses on the time relationship of the two signals while the other focuses on the amplitude. Both the two methods indicate the breakdown events happened at the end of the linac and more likely in the first or the second load cell