First Energy Efficient RF Sources Workshop
by Erk Jensen (CERN), Charlotte Houghton (STFC)
Attendees of the EnEfficient RF Workshop at the Cockcroft Institute, June 2014.
Image credit: Cockcroft Institute
The first Energy Efficient RF Sources workshop, supported by EuCARD-2, took place in June 2014 at the Cockcroft institute in the UK. Over 40 delegates and 18 speakers were part of the two day workshop which discussed state-of-the-art RF sources.
In the early days of particle accelerators, RF experts concentrated their design work on cavities and amplifiers with large acceleration in mind. Later, when the beam currents in accelerators increased, the focus of their ingenuity shifted towards coping with beam loading, better beam stability and increasing beam power. With demands for ever increasing beam energy and power, the overall energy consumption has now clearly become a major concern; large future particle accelerators must remain economically and ecologically sustainable and acceptable, so the overall power conversion efficiency has taken centre stage. Optimization of this efficiency could reduce both power consumption and wasted energy, both relevant for the society at large. At this Daresbury workshop, these concerns were discussed among international experts, and many novel and interesting solutions to make better RF systems were proposed.
Workshop highlights included, pioneering ideas proposed to substantially increase the power conversion efficiency of high power klystrons. Klystrons are Multi-Megawatt RF power amplifiers at the heart of many particle accelerators. While present-day klystrons are limited to efficiencies below 70%, the proposed improvements may push efficiencies to 90%. Much attention was also devoted to high power solid-state amplifiers. These amplifiers are still limited to much smaller power limits than vacuum electronic devices, but the trend over the last decade is very promising; and it is predicted they will become important in the future. Inductive output tubes (IOT’s), combine the advantages of grid tubes, this allows them to run without DC current, i.e. at lower power consumption. With the advantages of high frequency klystrons, IOT’s do not yet reach the power levels needed in accelerators, but promise better efficiency. This has encouraged recent results and plans for further research.
The two-day workshop, which is part of the EnEfficient EuCARD-2 work package, addressed the above interesting and promising topics and more. The workshop included a tour of the Versatile Electron Linear Accelerator (VELA), located at the Daresbury Laboratory.
