THM, Friedberg, Germany
TEMF, TU Darmstadt, Darmstadt, Germany
GSI, Darmstadt, Germany
GHz transition radiation monitors (GTRs) can be used to measure longitudinal beam profiles even for low ß beams. In comparison to traditional methods e.g., Fast Faraday Cups (FFCs) and Feschenko monitors, GTRs are a non-destructive measurement method and are able to resolve bunch-by-bunch longitudinal profiles at the same time. In our case, we plan to measure the transition radiation outside the beam line through an RF-window with an 8 GHz broad band antenna. At the border of the RF-window the transition radiation is partially reflected propagating in the beam line backwards. In this contribution, we show a study of different geometries to suppress reflections generated at the transition to the RF-window. For higher permittivity the strength of these reflections becomes stronger, simultaneously reducing the measurable signal strength at the antenna. Secondly the RF-window material must be UHV usable and should be durable like Alumina or Peek.
GSI, Darmstadt, Germany
Controlling stored beams in particle accelerators requires specially designed RF signals, such as needed for spill control via transverse excitation. The software-defined radio (SDR) technology is adopted as a low cost, yet highly flexible setup to generate such signals in the kHz to MHz regime. A feedback system is build using a combination of digital signal processing with GNU Radio and RF Network-on-Chip (RFNoC) on a Universal Software Radio Peripheral (USRP). The system enables digitization of signals from particle detectors and direct tuning of the produced RF waveforms via a feedback controller – implemented on a single device. To allow for triggered operation and to reduce the loop delay to a few ms, custom OOT and RFNoC blocks have been implemented. This contribution reports on the implementation and first test results with beam of the developed spill control system.
