A Compact 500 MHz 65 kW Solid-State Power Amplifier for Accelerator Applications

The Paul Scherrer Institut (PSI) currently operates a klystron amplifier on the booster ring of the Swiss Light Source (SLS). In order to have an optional radio frequency (RF) source for the booster cavity, we have been developing a compact 500 MHz 65 kW solid state RF amplifier. An important goal in this development is the optimization of efficiency at any given operating point. In order to achieve this, each RF module has been equipped with its own direct-current (DC) Power Supply Controller (PS Controller), providing sufficient intelligence (control logic, monitoring of sensors, analog-to-digital and digital-to-analog conversion, interlock check, etc.) to adjust the drain and bias voltages in a fully independent and automatic way. With this technique it is possible to maximize the overall efficiency at any given RF output power. Considerable effort has been made in order to obtain extensive measurements from each individual module with the aim of investigating the behaviour of such a large number of combined arrays. We will discuss the amplifier design and present the results of measurements.