Speaker
Description
One of the most actual problems of modern physics is the development of powerful radiation sources in the THz band. At the moment, the highest pulse and average power in the THz band are realized by the fast-wave devices – free-electron lasers and gyrotrons. The gyrotrons are vacuum electronics devices based on the stimulated cyclotron radiation of electrons moving along helical trajectories in an external magnetic field. To increase operation frequency, which is essential for such applications as controlled fusion, spectroscopy, and medicine, we need magnetic systems (solenoids) with high magnetic fields. For example, gyrotrons for fusion devices like ITER recently achieved an impressive output power of 1 MW in continuous wave (1000 s) regimes at the frequency of 170 GHz. Such gyrotron system used cryomagnet with 7T field intensity and 160 mm hot bore produced by JASTEC Ltd (Japan). For the next generation (DEMO, TRT, SPARC tokamaks), frequencies about 230-260 GHz is proposed. Gyrotrons with 30-40T pulsed magnets cooled by liquid nitrogen demonstrate frequency up to 1.3 THz with pulse duration several tens microseconds, and some applications need higher frequencies. Thus, it makes it a challenge to create much more intensive magnets. All magnetic systems for gyrotrons have specific requirements for field profile, hot bore, homogeneity, stability, etc. This report aims to formulate the demands and R&D goals for the magnetic technology community to develop novel magnetic systems for gyrotrons. The most interesting for nuclear fusion looks cryomagnets based on high-temperature superconductors. On the other hand, pulsed magnets with reasonable repetition frequency and field closed to 80-90 T for high power, ultra-high frequency (up to 2 THz) pulsed radiation sources for spectroscopy applications and diagnostic of various media.
Gyrotrons development is supported by IAP RAS project 0035-2019-0001
