Gary Eden

Member of National Academy of Engineering, IEEE Fellow,University of Illinois,US

Advances in Microcavity Plasma Science and Applications: Vuv Photolithography, Atomic Clocks, and 3D Photonic Crystals 

 

Edl Schamiloglu

IEEE Fellow,University of New Mexico,America

The Evolution of the Relativistic Magnetron

The cavity magnetron is the most compact, efficient source of high-power microwave (HPM) radiation. High- and low-power magnetrons are used in many applications, such as radar systems, plasma generation for semiconductor processing, and the most common, microwave ovens for home and industrial use. Since the invention of the magnetron in 1921 by Hull [1,2] (as a high-current switch - Hull did not mention microwave generation at all in his initial work), scientists and engineers have improved and optimized magnetron technology by altering the geometry, materials, and operating conditions, as well as by identifying new applications. A major advance in magnetrons for high power applications was the relativistic magnetron introduced by Bekefi and Orzechowski at MIT (USA, 1976) [3], followed by the invention of the relativistic magnetron with diffraction output (MDO) by Kovalev and Fuks [4] at the Institute of Applied Physics (Soviet Union, 1977). This presentation will review the evolution of the relativistic magnetron from its roots to its most recent incarnations [5].

1. A.W. Hull, “The effect of a uniform magnetic field on the motion of electrons between coaxial cylinders,” Phys. Rev. 18, 31–57 (1921).

2. A.W. Hull, “The magnetron,” J. Am. Inst. Electr. Eng. 40, 715–723 (1921).

3. G. Bekefi and T.J. Orzechowski, “Giant microwave bursts emitted from a field emission, relativistic-electron-beam magnetron,” Phys. Rev. Lett. 37, 379–382 (1976).

4. N. Kovalev, B. Kol’chugin, V. Nechaev, M. Ofitserov, E. Soluyanov, and M. Fuks, “Relativistic magnetron with diffraction coupling,” Sov. Tech. Phys. Lett. 3, 430–434 (1977).

5. D. Andreev, A. Kuskov, and E. Schamiloglu, “Review of the relativistic magnetron,” Matter Radiat. Extremes 4, 067201 (2019).

This research was sponsored by ONR Grant N00014-23- 1-2072.

 

Manfred Thumm

IEEE Fellow,Karlsruhe Institute of Technology, Germany

Status of High-Power Gyrotrons for Electron Cyclotron Heating and Current Drive in ITER and Beyond

Abstract - The International Thermonuclear Experimental Reactor (ITER) in Cadarache, France, will be equipped with 20 MW Electron Cyclotron Heating and Current Drive (ECH&CD), 20 MW Ion Cyclotron Heating and Current Drive (ICH&CD) and 33 MW Neutral Beam Injection Heating and Current Drive (NBIH&CD). ECH&CD will be the first auxiliary heating and non-inductive current drive method used on the tokamak ITER, due to the very successful development and industrial availability of 170 GHz MW-class Continuous Wave (CW) gyrotrons and corresponding low-loss, evacuated, corrugated waveguide millimeter (mm)-wave HE11-hybrid mode transmission lines. Twenty years ago, NBIH using neutralized positive ions ( 100 keV) was the major and favorite additional heating method employed for plasmas in worldwide thermonuclear fusion research. However, since NBI systems with 0.8-1.0 MeV negative ions are needed for reactor-type devices, NBIH&CD for ITER is still under R&D. The 20 MW 170 GHz ITER ECH&CD system (24 MW installed power from 24 gyrotrons) shall provide the following H&CD functionalities: plasma start-up and plasma ramp-down, plasma heating and non-inductive current drive, as well as plasma stabilization. Eight gyrotrons will be provided by the Russian Federation (RF) Domestic Agency (DA) [1], eight by the Japan (JA) DA [2], six by the European (EU) DA [3,4] and two by the India (IN) DA, made in Russia. The US DA is responsible for providing the corrugated transmission line system from the RF building, housing the gyrotrons, HV power supplies and auxiliaries, to the torus vessel. The ECH waves will be injected into the plasma via one Equatorial Launcher (max. 3x8 EC-wave beams) or/and four Upper Launchers (4x8 antenna waveguides for max. 24 EC- wave beams), controlled by waveguide switches.

This review reports on the status of the three types of gyrotrons for ITER. It starts with a general introduction to the specific fast-wave gyrotron interaction principle, followed by a short description of the main components of modern long-pulse fusion gyrotrons (magnetron injection electron gun (MIG), beam tunnel, cavity, quasi-optical output coupler, synthetic diamond output window, and single-stage depressed collector). The three different types of ITER gyrotrons will be described by a comparison of their components. Their achieved output parameters will be discussed.

The last part of this report will present the status of the development of advanced gyrotrons for future fusion power plants as, e.g. a Demonstration plant DEMO. These will be tubes with higher frequencies, higher power (e.g. 2 MW coaxial-cavity gyrotrons), multi-frequency (multi-purpose) gyrotrons, and stepwise frequency tunable tubes for plasma stabilization. In addition, frequency and phase stabilization via PLL techniques and injection locking will discussed [1, 5-7].

Keywords – Nuclear fusion energy, ITER and DEMO tokamaks, electron cyclotron heating and current drive (ECH&CD), megawatt-class, continuous wave (CW) gyrotrons, 2 MW coaxial-cavity gyrotrons, multi-frequency (multi-purpose) gyrotrons, stepwise frequency tunable gyrotrons, very-high-frequency gyrotrons, PLL stabilization and injection locking of gyrotrons

[1] Denisov, G.G., et al., New developments of megawatt power gyrotrons in Russia. 21st Joint Workshop on Electron Cyclotron Emission (ECE) and Electron Cyclotron Resonance Heating (ECRH) (EC21), June 20-24, 2022, Cadarache, France, Mo-11.

[2] Kajiwara, K., et al., Progress of the EC system for ITER in Japan. 21st Joint Workshop on Electron Cyclotron Emission (ECE) and Electron Cyclotron Resonance Heating (ECRH) (EC21), June 20-24, 2022, Cadarache, France, Mo-01

[3] Goodman, T.P., et al., Tests and qualification of the European 1 MW, 170 GHz CW gyrotron in an ITER relevant configuration at SPC. 47th Int. Conf. on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz 2022), Aug. 28-Sep. 2, 2022, Delft, The Netherlands, Mo-AM-1-3

[4] Rzesnicki, T., et al., European 1 MW, 170 GHz CW gyrotron prototype for ITER- Long-pulse operation at KIT. 47th Int. Conf. on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz 2022), Aug. 28-Sep. 2, 2022, Delft, The Netherlands, Mo-PM2-1-4

[5] Krier, L., et al., Progress on the frequency stabilization of MW-class 140 GHz gyrotrons at W7-X with a phase-locked loop. 21st Joint Workshop on Electron Cyclotron Emission (ECE) and Electron Cyclotron Resonance Heating (ECRH) (EC21), June 20-24, 2022, Cadarache, France, Mo-14

[6] Thumm, M.K.A., et al., High-power gyrotrons for electron cyclotron heating and current drive. Nucl. Fusion, 59, No. 7, 073001 (37pp) (2019), doi.org/10.1088/1741-4326/ab2005

[7] Thumm, M., State-of-the-art of high-power gyro-devices and free electron masers. Journal of Infrared, Millimeter, and Terahertz Waves, 41, No. 1, 1-140 (2020), doi.org/ 10.1007/s10762-019-00631-y

Cheng-Wei Qiu

OSA Fellow,National University of Singapore, Singapore

Geometric Semimetal Photodetectors for Mid-infrared Light