Design of E×B multistage depressed collector concepts for high-power fusion gyrotrons
C. Wu, I. Pagonakis, G. Gantenbein, S. Illy, M. Thumm, J. Jelonnek
Proc. 42th Int. Conf. Infrared, Millimeter and Terahertz waves (IRMMW-THz), 2017, Sep, pp. 1–2
The introduction of advanced Multistage Depressed Collectors (MDC) to high-power fusion gyrotrons will be the key to increase the gyrotron overall efficiency above 60 % as required for future DEMOnstration power plant. MDCs which base on the E×B drift concept might solve the fundamental issue of handling the secondary electrons. To consider the effect of secondary electrons in a stationary state, full 3D Particle-In-Cell (PIC) simulations are performed. A novel two-stage collector designed using PIC is presented which shows an excellent collector efficiency of up to 77 %. Moreover, the undesired generation of secondary electrons only reduces the efficiency by 1 %, compared to a typical 10 % efficiency reduction in other known classical concepts.