Recent experiments with the European 1MW, 170GHz industrial CW and short-pulse gyrotrons for ITER

Abstract

The European Gyrotron Consortium (EGYC) is developing the European 1 MW, 170 GHz Continuous Wave (CW) industrial prototype gyrotron for ITER in cooperation with Thales Electron Devices (TED) and Fusion for Energy (F4E). This conventional, hollow-cavity gyrotron, is based on the 1 MW, 170 GHz Short-Pulse (SP) modular gyrotron that has been designed and manufactured by the Karlsruhe Institute of Technology (KIT) in collaboration with TED. Both gyrotrons have been tested successfully in multiple experiments. In this work we briefly report on the results with the CW gyrotron at KIT and we focus at the experiments at the Swiss Plasma Center (SPC). In addition, we present preliminary results from various upgrades of the SP tube that are currently tested at KIT.

Development and Experimental Verification of an XY-Table for the Optimization of the Alignment of High-Power Gyrotrons

“…However, this fact does not reduce the importance of the XY-table, when the superconducting magnet is not equipped with dipole coils. This alternative procedure was followed at the SPC [18] for the proper alignment of the European 1-MW, 170-GHz CW Industrial prototype gyrotron, by using a modification of the design presented in Fig. 2.…”

A New Lumped Approach for the Simulation of the Magnetron Injection Gun for MegaWatt-Class EU Gyrotrons

“…The emitter ring itself is made of a material which can withstand the high operational temperatures required and that promotes electron emission by having low material-tovacuum work function. In the case of the European gyrotron for ITER [7,8], of special interest here, the emitter is constituted by a substrate of sintered tungsten impregnated by barium-calcium aluminate. To generate the amount of current necessary to drive, e.g., the 1MW ITER gyrotron, the surface of the emitter ring must reach temperatures of about 1200 K. An electrical heating element is placed purposely in the cavity formed by the emitter ring and the thermal shields, as shown in Figure 3, labeled as "Filament cavity".…”

“…Among them, as far as the MIG's cathode is concerned, we find the design of a suitable control system to guarantee a constant current [11], which, in fact, tends to decay during the gyrotron operation, jeopardizing the device performance. During the long pulse tests performed on the 1MW, 170 GHz European Gyrotron prototype for ITER, for instance, it has been observed that the cathode current undergoes a drop of more than 20% over the course of few seconds, after the beginning of the shot [7,8,12]. Up to now, the main technique utilized to counteract this phenomenon consists in the pre-programming of heating sequences of the MIG's cathode, to reach the desired current level during the gyrotron operation [11].…”

“…In this work, we concentrate on the test-case of the MIG of a European gyrotron designed for ITER (1 MW and 170 GHz [7,8,12]), and we develop a lumped-parameter dynamic model for its cathode that is capable of capturing the physical phenomena that are responsible for the current drop in the gyrotrons, when operated at high power levels. The purpose behind the lumped model development is twofold: First, having a numerical model able to predict the evolution of the system can allow operators to calculate and implement in the experiments different sequences of input heating power, as to minimize the occurrence of the current drop when performing controlled tests.…”

“…The values used as input time series in the simulations are experimental values obtained at the Fusion for Energy FALCON facility, currently operational at EPFL Lausanne. The radiative heat terms, thermal resistances, and beam heat are calculated according to Equations ( 5)- (7). Tn1 and Tn2 represent the average temperature of the nosecone seen by mass M5; Tw and Tp represent the average temperature of the MIG wall and of the prolongator.…”