State-of-the-Art of High-Power Gyro-Devices : Update of Experimental Results 2023

This report presents an update of the experimental achievements published in the review "State- of-the-Art of High-Power Gyro-Devices and Free Electron Masers", Journal of Jnfrared, Millimeter, and Terahertz Waves, 41, No. 1, pp 1-140 (2020) related to the development of gyro-devices (Tables 2-34). Emphasis is on high-power gyrotron oscillators for long-pulse or continuous wave (CW) operation and pulsed gyrotrons for many other applications. In addition, this work gives a short update on the present development status of frequency step-tunable and multi-frequency gyrotrons, coaxial-cavity multi-megawatt gyrotrons, complex two-section stepped cavity gyrotrons, gyrotrons for technological and spectroscopy applications, relativistic gyrotrons, !arge orbit gyrotrons (LOGs), quasi-optical gyrotrons, fast- and slow-wave cyclotron autoresonance masers (CARMs ), • gyroklystron-, gyro-TWT- and gyrotwystron amplifiers, gyro-harmonic converters, gyro-BWOs and dielectric vacuum windows for such high-power mm-wave sources. Gyrotron oscillators (gyromonotrons) are mainly used as high power millimeter wave sources for electron cyclotron heating (ECH), electron cyclotron current drive (ECCD), stability control and diagnostics of magnetically confined plasmas for clean generation of energy by controlled thermonuclear fusion. ... mehrThe maximum pulse length of commercially available 140 GHz, megawatt gyrotrons employing synthetic ·diamond output windows is 30 minutes (CPI and European KIT-SPC-THALES collaboration). The world record parameters of the European tube are: 0.92 MW output power at 30 min. pulse duration, 97.5% Gaussian mode purity and 44% efficiency, employing a single-stage depressed collector (SDC) for electron energy recovery. PLL­frequency stabilization of such tu bes has been demonstrated. A 1.5 MW version of this gyrotron is under development (JPP-KIT-THALES). The maximum output power of 1.5 MW in 4.0 s pulses at 45% efficiency was generated with the QST-CANON 110 GHz gyrotron. The first Japan 170 GHz ITER gyrotron prototype achieved 1 MW, 800 s at 55% efficiency and holds the energy world record of2.88 GJ (0.8 MW, 60 min., 57 %). The Russian 170 GHz ITER gyrotron obtained 0.99 (l.2) MW with a pulse duration of 1000 (100) s and 57 (53) % efficiency. First frequency-injection-locked operation of a Russian 170 GHz-1 MW gyrotron has been demonstrated in short pulses using a PLL-frequency-stabilized 20 kW gyrotron master oscillator. The prototype tube of the KIT 2 MW, 170 GHz coaxial-cavity gyrotron (pulse duration 50 ms) achieved in 1 ms pulses the record power of2.2 MW at 48% efficiency and 96% Gaussian mode purity. High-power CW gyrotron oscillators have also been successfully used in materials processing. Such technological applications require tubes with the following parameters: f 2:, 24 GHz, P001 = 4-50 kW, CW, 'l'J 2:. 30%. Gyrotrons with pulsed magnet for various short-pulse applications deliver P001 = 210 kW
with 't = 20 µs at frequencies up to 670 GHz (ri = 20%), P001 = 5.3 kW at l THz (ri = 6.1%), and Pout = 0.5 kW at 1.3 THz (ri = 0.6%). The average powers produced by 94 GHz gyroklystrons, gyrotwystrons and gyro-TWTs are 10 kW, 5 kW and 2 kW, respectively.