The accurate characteristic analysis of corrugated waveguide transmission line (TL) for electron cyclotron resonance heating system is very important for future application in fusion plasma research, including the alignment, mode purity, transmission efficiency and power transmission capability. A test scheme for these purposes has been developed based on 105GHz/1MW/3s gyrotron for 40 meters...
Electron Cyclotron Heating (ECH) devices up to 6 MW have been used for plasma heating and current drive in KSTAR [1].The efficiency of the heating had been somewhat questionable since the increase of the electron temperature and the plasma stored energy saturated in some transport time scale (~10msec) are likely smaller than other heating device (e.g. NBI), and they are unexpectedly small in...
The use of cold tests (low power) for Quasi-Optic (QO) mode converter performance analysis and verification has been an important topic in Gyrotron research [1]. This involves the use of low-power coaxial cavity mode generators producing higher-order TE-modes at mm-Wave and THz frequencies, which can be converted to linear polarized Gaussian-like beams [2],[3]. Misaligned mode generators...
High power gyrotrons are normally axially symmetric, which applies to both the electron optics and the microwave optics from the electron gun up to the end of the cavity and this is crucial for the most efficient interaction between the electron beam and the desired mode. On the other hand, due to the symmetry, undesired modes can also be excited, which are in competition with the main mode...
The Electron Cyclotron Emission diagnostic for ITER will provide essential information for plasma operation and for establishing performance characteristics. It will measure Core and Edge Electron Temperature Profile, ELM (Edge Localized Mode) temperature transient, NTM (Neo-classical Tearing Mode) and TAE (Toroidal Alfvén Eigenmode) δT/Te, as well as contribute to the measurement of βp and...
The design, development, and characterization of a silicon carbide (SiC) based high-temperature black body source at 600 ºC for Electron Cyclotron Emission (ECE) measurements have been done. The design has been optimized for higher emissivity performance in the 65–140 GHz frequency range using CST Microwave Studio. The innovative design features a pyramid-based structure incorporating a heater...
We present a dual-frequency gyrotron for the electron cyclotron heating and current drive (ECH/ECCD) system to achieve steady-state tokamak plasma operation for future K-DEMO. We will use this dual-frequency gyrotron to study the transmission lines and a launching system, including nonlinear harmonic signals generated from the gyrotron, which interrupt the RF beam steering. The gyrotron...
The ITER Electron Cyclotron Resonance Heating (ECRH) and Current Drive (CD) system will be equipped with four identical Upper Launchers (ULs), each injecting up to eight 170 GHz beams in the plasma. The eight beams can be steered in two groups of four, by an Upper and a Lower Steering Mirror (USM, LSM). The UL optical design and steering range are tailored to its primary task of controlling...
Four Electron Cyclotron Heating Upper Launchers will be used in ITER to inject power at 170 GHz mainly for suppression of MHD instabilities, especially Neoclassical Tearing Modes. For each UL, the quasi-optical section injecting millimetre waves into the plasma consists of eight beams divided in two rows (upper and lower) reflecting on three fixed and one steering mirrors. A simplified model...
The COMPASS Tokamak is undergoing a significant upgrade to achieve a high toroidal magnetic field of $B_{\mathrm{T}}=5$~T, high current $I_{\mathrm{p}}\leq 2$~MA and a high density \cite{vondracek2021}. To ensure sufficient power for reaching a promising advanced confinement mode and controlling high $Z$ impurities in the plasma, a new Electron Cyclotron Resonance Heating (ECRH) system is...
The electron cyclotron (EC) heating & current drive (H&CD) system on ITER provides plasma heating by generating, transmitting, and launching high-intensity, high-frequency (170 GHz) electromagnetic wave energy steerable across the plasma cross-section. The transmission line (TL) subsystem connects the Matching Optics Unit (MOU) on each of the 24 gyrotrons to the 32 feed points in the four...
A primary contributor to the effectiveness of the ITER electron cyclotron (EC) heating & current drive (H&CD) transmission line (TL) is the distortion of the waveguide which has a strong, direct correlation with power transmission efficiency and electromagnetic mode purity. Two main sources of distortion are the deflection of the TL due to operational loads and misalignment of the waveguide...
We have designed a dual frequency gyrotron targeting frequencies of 142 GHz and 208 GHz. Prior to conducting a hot test on the gyrotron, it is essential to validate the output beam patterns of a designed mode converter launcher and a quasi-optic system with a low-power source. To achieve this, we designed mode generator cavity structures with perforated features to produce identical modes as...
High power microwaves are commonly applied in magnetically confined fusion devices for electron cyclotron (EC) resonance heating (ECRH) and current drive (ECCD). Whilst ECRH and ECCD have several favorable qualities in a future fusion power plant, ECCD is generally not as efficient at driving current as neutral beam injection (NBI) or lower hybrid current drive. Older microwave experiments...
Abstract: ECEI (Electron Cyclotron Emission Imaging) has been widely used in multiple nuclear fusion experimental devices and is one of the most important diagnostic systems on the HL-3 Tokamak for measuring the two-dimensional electron temperature perturbations. The optical system, as a key component of the ECEI diagnostic, determines the spatial resolution, field of view, and signal-to-noise...
In view of the realization of the Divertor Tokamak Test (DTT) facility, whose main goal is the study of heat exhaust on the divertor in conditions comparable to ITER and DEMO, up to 45 MW of additional heating shall be coupled to the plasma. The Electron Cyclotron (EC) system will provide most of the power, with 32 1-MW/170 GHz gyrotrons grouped in four clusters of eight sources. Each cluster...
This is an abstract for a poster presentation on the STEP HCD System design.
The Spherical Tokamak for Energy Production (STEP) device aims at net energy production. The primary aim of the Heating and Current Drive (HCD) system is to drive plasma current. A pure microwave HCD system was selected with two potential non-inductive operating configurations: (1) Electron Cyclotron (EC) and (2) a...
The paper present an effective and efficient coupling of the RF output beam of a gyrotron to the input of the transmission line. The investigation show that the quasi-optical system and the |Matching Optics Unit (MOU) can provide relative high TE11 mode contents for all modes operating at broadband (+/- 10 GHz) at center frequencies 136.170/204/238 GHz.
Recent Results from Electron Cyclotron Emission (ECE) Radiometer diagnostics in the presence of Electron Cyclotron Resonance Heating (ECRH)
VARSHA SIJU 1,2, S.K.PATHAK 1,2, B.K.SHUKLA1, R.L.TANNA1, R.KUMAR1, J.GHOSH1 and ADITYA-U TEAM2,
1 Institute for Plasma Research, Bhat, Gandhinagar – 382 428
2 Homi Bhabha National Institute (HBNI), Anushaktinagar, Mumbai-400094, India.
A radiometer...
Electron cyclotron (EC) radiation plays a critical role in the control of magnetohydrodynamic (MHD) instabilities. Therefore, high optical performance is demanded of EC antennas/launchers [1] in order to achieve effective instability suppression [2,3].
(Figure can be found in the attached abstract)
Figure 1: Schematic representation of thermal disturbances on ray paths (black arrows) as a...
We propose a mode generator cavity design capable of producing a higher-order rotating mode. This cavity generates a TE7,2 mode at 142 GHz and a TE9,3 mode at 208 GHz in a coaxial geometry, which is later used as an input mode for a launcher in an internal mode converter of a gyrotron. It consists of a perforated metallic cavity with a tapered inner rod to suppress the counter-rotating and...
SAMI-2 is a microwave based MCF diagnostic, which stands for Synthetic Aperture Microwave Imager. It is the second iteration of the original microwave back-scattering diagnostic SAMI and uses a phased antenna array to allow digital focusing of 2D doppler backscattered radiation. SAMI-2 operates in the 20 – 40GHz region, allowing it to probe the edge region of MAST-U plasmas. The antenna array...
Microwave absorbing materials are critical for several components including bolometers and beam dumps. Profound knowledge of the material properties and the material-wave interactions is a necessity for both design and use of these components. With the strong focus of the ITER absorbing components on ceramic materials, a systematic study was performed to methodically investigate the optical...
In SST-1 Tokamak, two ECRH systems are used 42GHz-500kW and 82.6GHz-200k to carry out varying experiments related plasma breakdown and heating at fundamental and second harmonic. The SST-1 tokamak is operated at 1.5T magnetic field and 42GHz ECRH system has been extensively for plasma start-up and heating. The 82.6GHz ECRH could not be used thoroughly due limitation in power as 200kW power is...
