In this paper the successful fabrication and assembly of the Multistage Depressed Collector (MDC) prototype developed at KIT for megawatt-class gyrotrons is described. The collector design bases on the application of the E×B drift concept for electron trajectory separation, a method that has been presented in [1-3]. The MDC prototype has a cylindrical structure with a helical isolation cut...
For long pulse gyrotron operation, the beam current of the gyrotron must be maintained at a target with high accuracy. In conventional method, the beam current has been adjusted with a pre-programmed control of the heater voltage to the cathode. The reason for changing the heater voltage during the pulse is to warm up the cathode as it cools down due to electron emission. This method requires...
The ECH gyrotron system at DIII-D currently consists of six 110-GHz Communications and Power Industries (CPI) diode tubes available for operation in the 2024 experimental campaign. The RF power is injected into DIII-D via four dual launchers (built by Princeton Plasma Physics Laboratory) located above the mid-plane of the machine. Eight existing transmission lines route from the four dual...
The Electron Cyclotron Heating and Current Drive system (EC HCD) plays a crucial role in all different plasma phase operations to achieve the objectives of ITER.
The European contribution to the ITER EC HCD system includes the procurement of the main part of the HV power supplies, six gyrotrons, all four upper launchers, all the ex-vessel waveguides, and the plant control system. It also...
To ensure advanced operation of KSTAR, KSTAR ECH power has been increased since 2017. ECH system was designed so that each ECH system has a source power of 1 MW and operates independently with its own individual power supply and transmission line and launcher [1]. To date, four 105/140 GHz dual frequency and one 170 GHz Russian gyrotrons have been installed and operated, out of a total 6 MW...
At the Wendelstein 7-X (W7-X) stellarator, a Phase-Locked-Loop (PLL) system has been implemented to stabilize the frequency of megawatt-class gyrotrons. The PLL system actively controls the accelerating voltage of the diode-type Magnetron Injection Gun (MIG) to counteract any unwanted frequency changes of the gyrotron output millimeter-wave beam. The accelerating voltage, which is applied...
In high power millimetre wave transmission systems, even small unwanted effects can have an impact on the system functionality. Therefore, a precise knowledge of the fields and loss mechanisms for realistic scenarios is required during the design phase. An important issue is the
effect of higher order modes (HOMs) on the performance of the equatorial and upper ECRH launchers for ITER. The...
