A new microwave system operating at the second harmonic of the Electron Cyclotron Resonance is presently being installed on TdeV. Its main objectives are to provide plasma heating and current drive up to the x-mode cut-off density (n_e = 7.5x10¹⁹ m ^-3). The microwave source consists of two 110 GHz, 0.7MW, 2s, GYCOM gyrotrons. The high voltage on each gyrotron is independently controlled with high power tetrodes to assure proper regulation and flexible control of the RF output power. The tetrodes are also used to switch off rapidly ( T - 2µs ) the high voltage in case of a fault. The microwave beam is transmitted to TdeV by both quasi-optical and waveguide components.

The control and protection system has a multi-level structure. The primary level is the hard-wired fail safe protection system that uses programmable logic devices (PLD). PLD technology offers versatility to implement sophisticated protection schemes and allows modification of the control logic when needed. This level ensures protection to personnel and critical equipment such as gyrotrons, tetrodes and transmission lines. It has approximately 100 I/Os per gyrotron and its response time is adjustable between 1µs and 50 ms depending on the type of fault detected. The second level consists of a programmable logic controller with 480 I/Os. It is used for over-all supervision, event sequencing, control and slower protection (Tmin= 60ms). The last level is the user interface, which uses a commercial software. Event synchronization is done by a CAMAC based optical fibre timing highway linking the waveform generators, data acquisition and control systems.

The paper will describe in details the control and protection systems and its components. Preliminary performance of the system with one gyrotron in operation will be presented.

* This work was funded by the Government of Canada, Hydro-Quebec and the Institut national de la recherche scientifique.