SLAC, Menlo Park, California, USA
LCLS-II's high beam rate of almost 1MHz and the requirement that several "high-performance" systems (such as MPS, BPM, LLRF, timing etc.) shall resolve individual bunches precludes the use of a traditional software based control system but requires many core services to be implemented in FPGA logic. SLAC has created a comprehensive open-source firmware framework which implements many commonly used blocks (e.g., timing, globally-synchronized fast data buffers, MPS, diagnostic data capture), libraries (Ethernet protocol stack, AXI interconnect, FIFOs, memory etc.) and interfaces (e.g., for timing, diagnostic data etc.) thus providing a versatile platform on top of which powerful high-performance systems can be built and rapidly integrated.
LBNL, Berkeley, California, USA
SLAC, Menlo Park, California, USA
JLab, Newport News, Virginia, USA
Fermilab, Batavia, Illinois, USA
The SLAC National Accelerator Laboratory is building LCLS-II, a new 4 GeV CW superconducting (SCRF) linac as a major upgrade of the existing LCLS. The SCRF linac consists of 35 ILC style cryomodules (eight cavities each) for a total of 280 cavities. Expected cavity gradients are 16 MV/m with a loaded QL of ~ 4 x 107. Each individual RF cavity will be powered by one 3.8 kW solid state amplifier. To ensure optimum field stability a single source single cavity control system has been chosen. It consists of a precision four channel cavity receiver and two RF stations (Forward, Reflected and Drive signals) each controlling two cavities. In order to regulate the resonant frequency variations of the cavities due to He pressure, the tuning of each cavity is controlled by a Piezo actuator and a slow stepper motor. In addition the system (LLRF-amplifier-cavity) was modeled and cavity microphonic testing has started. This paper will describe the main system elements as well as test results on LCLS-II cryomodules.