In order to improve the ability of the J-TEXT tokamak which firstly only had the ohmic heating, we had begun to develop the electron cyclotron resonance heating (ECRH) system since 2017. The first ECRH system with the frequency of 105 GHz and the output power of 500 kW for 1s was successfully operated in 2019. This system is a traditional one which consists of a gyrotron from GYCOM, a...
Eight reflecting gratings are installed into the plasma facing wall of ASDEX Upgrade (AUG) in order to provide a controlled second pass through the plasma center in 140 GHz heating scenarios with reduced single pass absorption. Four of these gratings are machined out of W1.4901 steel and coated with tungsten to increase the reflectivity. During plasma operation three of the W1.4901 gratings...
In Spherical Torus (ST) with relatively low toroidal field, electron Bernstein wave (EBW) is known to be an efficient heating mechanism for high density plasmas without accessibility problem even at low frequency. Over-dense plasmas beyond L cut-off density was obtained via direct XB mode conversion from perpendicular low-field-side injection in Versatile Experiment Spherical Torus (VEST),[1]...
We report the neoclassical tearing mode (NTM) stabilization experimental results by injection of the electron cyclotron (EC) beam in KSTAR, and its analysis by calculating tearing stability index Δ′. In KSTAR #31747 experiment, the neoclassical tearing mode (NTM) is intentionally induced, and the KSTAR plasma control system (PCS) injects EC beam to stabilize the NTM. Here the EC is injected...
Recent experiments in Heliotron J have delved into the response of energetic-particle-driven MHD
instabilities to electron cyclotron heating and current drive (ECH/ECCD) [1]. Specifically, we
conducted ECH modulation experiments to scrutinize mode stabilization and its underlying physical
mechanisms [2]. In our initial modulation experiment, the NBI power was modest at 90 kW in...
One of the main goals of the superconducting stellarator Wendelstein 7-X (W7-X) is to demonstrate steady state plasma operation at reactor relevant plasma parameters in discharge scenarios with a length of up to 30 minutes. For this reason, W7-X was equipped with a steady state capable 140 GHz electron cyclotron resonance heating (ECRH) system with an installed power of currently 8.3 MW....
In this contribution, recent results achieved at the FALCON test facility are presented. This versatile facility proves useful for testing continuous wave high-power gyrotrons, but also serves as a platform for testing the transmission line components and RF-loads for ITER and other future facilities. The gyrotron currently under test at SPC is the TH1509UA [1] gyrotron for the Divertor...
In the commissioning of JT-60SA, two ECRH systems were operated at 110 GHz with a small-diameter waveguide of 31.75 mm (Unit1) and 82/110/138 GHz with a large-diameter waveguide of 60.3 mm (Unit2) [1]. The large-diameter waveguide potentially has a larger mode conversion loss due to misalignment than the small-diameter waveguide, and its feasibility in a 100 m-class transmission line (TL) is...
