Measurements for low level RF control systems

Abstract

The low level RF control system for the European x-ray free electron laser, which is based on TESLA technology, requires information on a large number of signals and parameters which are either directly measurable as physical signals or must be derived from the physical signals. In most cases, calibrations are required to obtain the desired quantities. The measured signals are used in the real time feedback loops for field and resonance control, and for diagnostic purposes to support automation and exception handling. Good system models and powerful signal processors (including field programmable gate arrays and digital signal processors) combined with fast communication links allow for processing a large number of complex algorithms in real time. Several of these algorithms have been implemented at the free electron laser at Hamburg (FLASH) for evaluation and have increased the availability of the facility for user operation.

Interfaces and Communication Protocols in ATCA-Based LLRF Control Systems

“…According to the Xilinx datasheet the overall latency of the transmitter-receiver path for RocketIO blocks varies from 12.5 to 23 clock cycles (106.25 MHz) depending on the chosen configuration options. 5 Therefore, the latency of the custom protocol is from 117 ns to 216 ns. The output update rate for the XFEL field controller is 200 ns.…”

“…The LLRF system, based on SimCon 3.1L [3] that is currently installed in FLASH, controls one cryogenic module comprised of eight superconductive TESLA cavities [4]. The LLRF system of FLASH is based on the VME (Versa Module Eurocard) architecture [5], [6]. Since the XFEL accelerator needs almost 1000 cavities, the LLRF system will consist of more than 32 RF stations.…”

Effects of correlations between particle longitudinal positions and transverse plane on bunch length measurement: a case study on GBS electron LINAC at ELI-NP

“…Moreover, the electron bunch length must be tuned according to the laser bunch length. Consequently, the measurement of the properties of the single bunch and the whole train of bunches is a crucial task for beam diagnostic [16,24,25].…”

<title>Decomposition of MATLAB script for FPGA implementation of real time simulation algorithms for LLRF system in European XFEL</title>

“…The idea behind them is to implement mathematical models of RF station components like cavities, klystron, waveguides, circulators, piezo, etc. in dedicated hardware system using FPGA and DSP chips for fast, parallel data processing [7]. Such electronics with the RF input and output stage can create the real test bench simulating accelerator operation environment and, what is really important, is completely independent of the hardware and software technologies used to build the LLRF system, fig.…”