The first four 352.2 MHz - 150 kW solid state amplifiers (SSA) were connected to the booster RF cavities during the long winter shutdown. They were brought into operation at the intermediary machine restart in March 2012. The system was debugged and calibrated in a few days. The new transmitter includes the SSAs delivered by ELTA/AREVA, two 400 kW - 280 V AC/DC power converters (one spare), implemented by the Power Supply Group and a new low level RF and control system built by the RF Group and the Accelerator Control Unit.


Fig. 153: Control synopsis of the new booster RF system with four SSAs powering the accelerating cavities.

Figure 153 shows the control synopsis of the booster RF system under typical operation conditions in pulsed mode at the 10 Hz repetition rate. A 3.2 F capacitor bank was installed on the 280 V DC supply in order to smooth out the power drawn from the mains and limit the flicker at 10 Hz. Thanks to filtering, only 366 kW AC are drawn from the mains. Under similar operation conditions, this is about one third of the power demand of the former klystron transmitter for which such filtering was not possible.

After debugging and tuning, the new booster RF system has been operating very well since the machine restart in user mode in May 2012. So far, only one of about one thousand RF modules that compose the SSA has been in fault. Thanks to the built-in redundancy, this failure did not interrupt operation. Fine tuning is still ongoing with no impact on operation.

During the commissioning of the SSAs for the booster, some unforeseen effects were observed that are inherent to the combination of many RF amplifier modules operating at high power. Although these effects have no impact on the booster SSAs operated in pulsed regime, some modifications are necessary for the three SSAs still to be delivered by ELTA for operation in CW on the storage ring. The process of identifying and implementing these modifications has caused a substantial delay in the delivery of the next three SSAs. The revised schedule foresees their connection, in succession, to the three new HOM damped cavities on cell 23 in August 2013, January 2014 and March 2014, respectively.