CAMD Upgrades to Solid State RF

CAMD has recently reached an important milestone with the upgrade of its RF system.  The RF provides the power that accelerates the electron beam to its operational energy and keeps the electrons at that energy while they emit synchrotron radiation.  Figuratively, one might compare the RF to a heart that keeps the blood – the electron beam ¬– flowing, bringing life to the accelerator.  

Traditionally, RF is generated within a tube accelerator called a klystron and this has been used at CAMD since first light in 1991.  The technology has advanced to solid state RF generators and our style of klystron is no longer manufactured.  Unfortunately, klystrons age with time and use and require periodic replacement. This led to CAMD, like other synchrotrons world-wide, to transition to solid state RF.  We have teamed with Ampegon Power Electronics AG to make this transition.

On July 12, 2021 we began the assembly and installation of our Ampegon solid-state RF system.  This system is based on multiple power modules that can each provide 1.5 kW from dual transistor amplifiers powered by a low voltage DC supply.  These modules are attached to a cavity combiner that, in our case, takes up to 64 modules.  We have installed 48 modules for up to 72 kW but, considering engineering tolerances, it is likely to be operated closer to 60 kW.  In just 3 days the system was connected to the accelerator and tested to 40 kW – our prior operating point for the klystron – and within 5 days it was providing power to a stored electron beam.

The importance of this upgrade for CAMD and its users cannot be overstated.  With the klystron aging and providing reduced power we were limited in our operations.  Our superconducting wavelength shifter and multipole wiggler insertion devices were not operated at full power – or at all – and the ring energy was reduced.  With the new RF, operations have been resumed to normal and the system is providing a reliable and rock-steady level of RF power.  Through the upcoming weeks we anticipate that this will allow us to provide users with higher-energy photons and will extend the lifetime of the stored beam, both aspects allowing users to take better data in less time.

Ampegon cavity combiner pictured with one RF module		Frame for the amplifier system.	Operational RF system.