Zero-Suppression Trigger Mode for GEM detector measurement system

A novel approach to a trigger mode in the GasElectron Multiplier (GEM) detector readout system is presented.The system is already installed at WEST tokamak. The articlebriefly describes the architecture of the GEM detector and themeasurement system. Currently the system can work in twotrigger modes: Global Trigger and Local Trigger. All trigger processingblocks are parts of the Charge Signal Sequencer modulewhich is responsible for transferring data to the PC. Therefore,the article presents structure of the Sequencer with details aboutbasic blocks, theirs functionality and output data configuration.The Sequencer with the trigger algorithms is implemented inan FPGA chip from Xilinx. Global Trigger, which is a defaultmode for the system, is not efficient and has limitations due tostoring much data without any information. Local trigger whichis under tests, removes data redundancy and is constructed tosend only valid data, but the rest of the software, especially on thePC side, is still under development. Therefore authors proposethe trigger mode which combines functionality of two existingmodes. The proposed trigger, called Zero Suppression Trigger, iscompatible with the existing interfaces of the PC software, butis also capable to verify and filter incoming signals and transferonly recognized events. The results of the implementation andsimulation are presented

Soft X-ray diagnostic system upgrades and data quality monitoring features for tokamak usage

The validation of the measurements quality after on-site diagnostic system installation is necessary in order to provide reliable data and output results. This topic is often neglected or not discussed in detail regarding measurement systems. In the paper recently installed system for soft X-ray measurements is described in introduction. The system is based on multichannel GEM detector and the data is collected and sent in special format to PC unit for further postprocessing. The unique feature of the system is the ability to compute final data based on raw data only. The raw data is selected upon algorithms by FPGA units. The FPGAs are connected to the analog front-end of the system and able to register all of the signals and collect the useful data. The interface used for data streaming is PCIe Gen2 x4 for each FPGA, therefore high throughput of the system is ensured. The paper then discusses the properties of the installation environment of the system and basic functionality mode. New features are described, both in theoretical and practical approach. New modes correspond to the data quality monitoring features implemented for the system, that provide extra information to the postprocessing stage and final algorithms. In the article is described also additional mode to perform hardware simulation of signals in a tokamak-like environment using FPGAs. The summary describes the implemented features of the data quality monitoring features and additional modes of the system

New directions in the construction of tokamak plasma impurity diagnostics systems

Thermonuclear fusion will be a promising energy source soon. Sophisticated systems are called tokamaks (toroidal chambers with magnetic coils) to generate hot plasma. Currently, the fusion process is not yet fully controlled. To better understand it, scientists use diagnostic systems that record plasma behavior. A particular group of diagnostic systems is responsible for the analysis of plasma impurities. The article briefly discusses the method of producing energy from a controlled nuclear fusion. Then, it presents groups of diagnostic systems in terms of their functions and focuses on systems dedicated to monitoring and analyzing plasma impurities. Parameters and limitations of representative currently used diagnostics systems for plasma impurities are described. In the end, the functional and technical requirements of plasma diagnostic systems designed for new tokamaks such as ITER and DEMO are discussed