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.
The search for new technologies in the field of plasma diagnostics entails the increasing demands on the radiative stability of the used materials due to development and usage of fusion facilities, where the study of processes occurring during the interaction of radiation with matter has become particularly important. Currently, a new X-ray imaging detection technology is required for tokamaks such as ITER. X-ray detectors that are being used in existing equipment may rapidly degrade due to large neutron fluxes characteristic for the tokamak environment. Despite the relatively wide use of semiconductor detectors to record SXR radiation (generally ionizing radiation), gas detectors are promising candidates that are suited much better for use in future fusion reactors given their resistance to neutron radiation. The most promising representative of the new gas detector class is the so called Gas Electron Multiplier (GEM), which is characterized by high amplification factor of the primary charge that is originated from photon absorption. Its main advantages are the compactness of the detector, good temporal and spatial resolutions, the ability to discriminate against photon energy and better neutron resistance compared to existing systems. All this makes such a detection system a potentially better candidate for soft X-ray measurements in the ITER and DEMO reactors. In this work, a new type of detection system based on GEM technology was proposed for soft X-ray measurements in the ITER reactor-oriented research, which is being developed at IPPLM.
KEYWORDS: Field programmable gate arrays, Computing systems, Data acquisition, Signal processing, Sensors, Signal detection, Plasma, Data processing, X-rays, Analog electronics
The presented system is used for monitoring of the plasma impurities in the tokamak. It is done by measuring radiation in Soft X-Ray range with the use of a GEM-based detector. Acquired data is transferred through the whole system with low latency. Presented system can be divided into many parts - detector, analog electronics, FPGA, PCIe transmission line and computer system with high-performance CPU. This work will concentrate on synchronization between FPGA, which write data to the memory on the CPU side and computational part, which is executed in the computer. In long-running measurements, there is a synchronization problems which can arise. There is a difference in variables based on which the execution time of both parts is dependent. Working on measurements of radiation of plasma impurities requires limits in terms of latency. This paper presents reasons, descriptions and solutions for such problems.
KEYWORDS: Systems modeling, Data modeling, Field programmable gate arrays, Control systems, Plasma diagnostics, Plasma systems, Sensors, Human-machine interfaces
The paper describes the communication model implemented for tokamak plasma diagnostics systems. The approach was tested for the SXR measurement system working with the GEM detector. The model describes the interfaces used for integration of various firmware and software implementations, done in the system. The purpose of the applications is to control and manage the system with acquisition of measurement data. The applications are often design by various authors, therefore it is necessary to create a common communication model, for easy integration and upgrades of the components in the system.
This paper focuses on implementation of the charge signal sequencer in FPGA chip dedicated for GEM detector. First is described structure of GEM detector for WEST experiment developed by IPPLM and Warsaw University of Technology. Then the article explains why signal sequencer is needed in the new system and shortly presents how it works. It collects data from all detector channels and sends it out in unambiguous order to PC. It plays a big role in a data pipeline. Proper order of data improves parameters of the system, decreases the latency and simplifies computations on PC side. The article explains technical aspects of the implementation like architecture, blocks, dataflow or configuration features. In the end, there are presented results of the implementation.
This document was prepared to discuss the high voltage generator module which can be used to supply X-ray Gas Electron Multiplier (GEM) detector. Emphasis was placed on the description of the module’s hardware structure. Furthermore, the detector protecting mechanisms the against the damage have been presented and described.
KEYWORDS: Field programmable gate arrays, Diagnostics, Sensors, Plasma diagnostics, Plasma, Data processing, Signal processing, Digital signal processing, Computer architecture, Physics
This paper discusses the model and the development methodology that was proposed in the implementation process of the heterogeneous system for the WEST thermal fusion reactor. The objective was to provide a systematic approach to provide a heterogeneous device to handle high-throughput workloads with low-latency for the WEST Soft X-Ray impurities diagnostic. The presented mechanism is dedicated to augment the system applicability to a wider area of instrumentation for high-scale physics experiments.
We present the concept of data distribution and dispatching software which is prepared for low latency and high throughput SXR measurement system developed by our group. Its scope includes handling data acquisition from multiple FPGA chips, execution of numerical algorithms with the use of multiple threads and post calculation storage and transfer. Data transfer to CPU side is done with usage of DMA via PCIe interface with specially developed Linux driver. This paper describes the need and details of discussed part of the system.
Article presents latest updates in development of automated cage for optogenetic experiments. New hardware concept for data concentrator is presented with ability to fuse incoming data from multiple sources. Along with hardware updates, a new web interface for controlling the hardware is presented as well as localization system development.
The measurement system based on GEM - Gas Electron Multiplier detector - is developed for soft X-ray diagnostics of tokamak plasmas. The multi-channel setup is designed for estimation of the energy and the position distribution of an Xray source. The focal measuring issue is the charge cluster identification by its value and position estimation. The fast and accurate mode of the serial data acquisition is applied for the dynamic plasma diagnostics. The charge clusters are counted in the space determined by 2D position, charge value and time intervals. Radiation source characteristics are presented by histograms for a selected range of position, time intervals and cluster charge values corresponding to the energy spectra.
The advanced Soft X-ray (SXR) diagnostics setup devoted to studies of the SXR plasma emissivity focusing on the energy range of tungsten emission lines is at the moment a highly relevant and important for ITER/DEMO as W became a plasmafacing material and, therefore, plasma contamination by W and W transport in the plasma must be understood and monitored. The Gas Electron Multiplier (GEM) based SXR radiation detecting system under development by our group with a spatial and energy-resolved photon detecting chamber may become such a diagnostic setup; however, many physical, technical and technological aspects must be taken into consideration. This work presents the results of preliminary tests and simulations of the research into the optimal design of the detector’s internal chamber. The study of the influence of different GEM foils on the properties and distribution of the electron avalanche as well as the effect of the high rate photon flux on GEM foil performance was performed. Effect of electrodes alignment allowed choosing the gap distances which maximize electron transmission was also examined. Finally, the optimal readout structure design was identified suitable to collect a total formed charge effectively.
This paper focuses on the model of the sequencer algorithm created in Matlab. The sequencer is used in the measurement system of 2nd generation for GEM detector. First, are described and compared two generations of the system. The article explains why sequencer is needed in the new system and presents how it works. It can collect data from many sources and send it out in unambiguous order. The model of the sequencer designed in Matlab allows adjusting its parameters to the specific process. The article explains technical aspects of the model, describes basic objects that were used to build the model. In the end, there are presented results. The sequencer is implemented in FPGA device.
The requirements given for GEM (Gaseous Electron Multiplier) detector based acquisition system for plasma impurities
diagnostics triggered a need for the development of a specialized software and hardware architecture. The amount of
computations with latency and throughput restrictions cause that an advanced solution is sought for. In order to provide a
mechanism fitting the designated tokamaks, an insight into existing solutions was necessary. In the article there is
discussed architecture of systems used for plasma diagnostics and in related scientific fields. The developed solution is
compared and contrasted with other diagnostic and control systems. Particular attention is payed to specific requirements
for plasma impurities diagnostics in tokamak thermal fusion reactor. Subsequently, the details are presented that justified
the choice of the system architecture and the discussion on various approaches is given.
KEYWORDS: Field programmable gate arrays, Feedback loops, Telecommunications, Computing systems, Data communications, Particle accelerators, Data processing, Algorithm development, Operating systems, Control systems
The paper presents the evaluation study of the performance of the data transmission subsystem which can be used in High Energy Physics (HEP) and other High-Performance Computing (HPC) systems. The test environment consisted of Xilinx Artix-7 FPGA and server-grade PC connected via the PCIe 4xGen2 bus. The DMA engine was based on the Xilinx DMA for PCI Express Subsystem1 controlled by the modified Xilinx XDMA kernel driver.2 The research is focused on the influence of the system configuration on achievable throughput and latency of data transfer.
This article presents recent development of the automated cage for optogenic experiments. A new electromagnetic localization system introduced to simplify localization system hardware infrastructure and measurement procedure is described. Preliminary experimental results are provided. Ongoing development of the implantable device in the context of communication protocols and utilization with a new localization system is covered.
Soft X-ray plasma measurement systems are mostly multi-channel, high performance systems. In case of the modular construction it is necessary to perform sophisticated system discovery in parallel with automatic system configuration. In the paper the structure of the modular system designed for tokamak plasma soft X-ray measurements is described. The concept of the system discovery and further automatic configuration is also presented. FCS application (FMC/ FPGA Configuration Software) is used for running sophisticated system setup with automatic verification of proper configuration. In order to provide flexibility of further system configurations (e.g. user setup), common communication interface is also described. The approach presented here is related to the automatic system firmware building presented in previous papers. Modular construction and multichannel measurements are key requirement in term of SXR diagnostics with use of GEM detectors.
KEYWORDS: Optogenetics, Control systems, Antennas, Curtains, Field programmable gate arrays, Detection and tracking algorithms, LED displays, Transceivers, Polishing, Physics
In this article there is presented an implementation of control system for the extended experiments involving both the advanced functionalities of home-cage environments and optogenetic mechanisms. The issues associated with the system from control perspective are shown. The introduced novel mechanisms of developed system are discussed. Exemplary upcoming experiments with the utilization of the system are presented.
This article is an overview of what has been implemented in the process of development and testing the GEM detector based acquisition system in terms of post-processing algorithms. Information is given on mex functions for extended statistics collection, unified hex topology and optimized S-DAQ algorithm for splitting overlapped signals. Additional discussion on bottlenecks and major factors concerning optimization is presented.
We present study of a software-hardware environment for developing fast computation with high throughput and low latency methods, which can be used as back-end in High Energy Physics (HEP) and other High Performance Computing (HPC) systems, based on high amount of input from electronic sensor based front-end. There is a parallelization possibilities discussion and testing on Intel HPC solutions with consideration of applications with Gas Electron Multiplier (GEM) measurement systems presented in this paper.
KEYWORDS: Sensors, MATLAB, Data modeling, Data acquisition, Field programmable gate arrays, Data processing, Clocks, Algorithm development, Detection and tracking algorithms, Process control
This article presents method of modeling in Matlab hardware architecture dedicated for FPGA created by languages like VHDL or Verilog. Purposes of creating such type of model with its advantages and disadvantages are described. Rules presented in this article were exploited to create model of Serial Data Acquisition algorithm used in X-ray GEM detector system. Result were compared to real working model implemented in VHDL. After testing of basic structure, other two structures were modeled to see influence parameters of the structure on its behavior.
This article presents a modular control system used in Eco-HAB experimentation system. Features specific to the solution are covered. Control system is described in details. The architecture is outlined in the context of requirements to be met. Modes of utilization of implantable device, time synchronization, localization service and antenna driving oscillation fine-tuning as well as preliminary experiments in preparation are described.
One of the requests from the ongoing ITER-Like Wall Project is to have diagnostics for Soft X-Ray (SXR) monitoring in tokamak. Such diagnostics should be focused on tungsten emission measurements, as an increased attention is currently paid to tungsten due to a fact that it became a main candidate for the plasma facing material in ITER and future fusion reactor. In addition, such diagnostics should be able to withstand harsh radiation environment at tokamak during its operation. The presented work is related to the development of such diagnostics based on Gas Electron Multiplier (GEM) technology. More specifically, an influence of neutron radiation on performance of the GEM detectors is studied both experimentally and through computer simulations. The neutron induced radioactivity (after neutron source exposure) was found to be not pronounced comparing to an impact of other secondary neutron reaction products (during the exposure).
KEYWORDS: Algorithm development, Sensors, Plasma, Field programmable gate arrays, Data acquisition, Signal detection, Calibration, Plasma diagnostics, Diagnostics, Iron
The measurement system based on GEM - Gas Electron Multiplier detector - is developed for soft X-ray diagnostics of tokamak plasmas. The multi-channel setup is designed for estimation of the energy and the position distribution of an Xray source. The focal measuring issue is the charge cluster identification by its value and position estimation. The fast and accurate mode of the serial data acquisition is applied for the dynamic plasma diagnostics. The charge clusters are counted in the space determined by 2D position, charge value and time intervals. Radiation source characteristics are presented by histograms for a selected range of position, time intervals and cluster charge values corresponding to the energy spectra.
The objective of this article is to present a prototype of miniature, low power implantable device, suitable for optogenetics. The device is designed to control the light stimulation by generating the signal that controls the LEDs. Another function of the device is to gather the data from measurement sensors, sending it through the wireless interface and to provide location service functionality.
An increased attention to tungsten material is related to a fact that it became a main candidate for the plasma facing material in ITER and future fusion reactor. The proposed work refers to the studies of W influence on the plasma performances by developing new detectors based on Gas Electron Multiplier GEM) technology for tomographic studies of tungsten transport in ITER-oriented tokamaks, e.g. WEST project. It presents current stage of design and developing of cylindrically bent SXR GEM detector construction for horizontal port implementation. Concept to overcome an influence of constraints on vertical port has been also presented. It is expected that the detecting unit under development, when implemented, will add to the safe operation of tokamak bringing creation of sustainable nuclear fusion reactors a step closer.
KEYWORDS: Sensors, Signal detection, X-rays, Field programmable gate arrays, X-ray detectors, Fusion energy, Data acquisition, Diagnostics, Amplifiers, Signal processing
The Triple Gas Electron Multiplier (T-GEM) is presented as soft X-ray (SXR) energy and position sensitive detector for high-resolution X-ray diagnostics of magnetic confinement fusion plasmas. Multi-channel measurement system and serial data acquisition for X-ray energy and position recognition is described. Fundamental characteristics are presented for two dimensional detector structure. Typical signals of ADC – Analog to Digital Converter are considered for charge value and position estimation. Coinciding signals for high flux radiation cause the problem for cluster charge identification. The amplifier with shaper determines time characteristics and limits the pulses frequency. Separation of coincided signals was introduced and verified for simulation experiments. On line separation of overlapped signals was implemented applying the FPGA technology with relatively simple firmware procedure. Representative results for reconstruction of coinciding signals are demonstrated.
KEYWORDS: Detection and tracking algorithms, Operating systems, Field programmable gate arrays, Digital signal processing, Sensors, Data processing, Parallel computing, Data communications, Data modeling, Signal processing
This article is an assessment of potential parallelization of histogramming algorithms in GEM detector system. Histogramming and preprocessing algorithms in MATLAB were analyzed with regard to adding parallelism. Preliminary implementation of parallel strip histogramming resulted in speedup. Analysis of algorithms parallelizability is presented. Overview of potential hardware and software support to implement parallel algorithm is discussed.
KEYWORDS: MATLAB, Sensors, Data processing, Data communications, Optimization (mathematics), Field programmable gate arrays, Data acquisition, Data analysis, Control systems, X-ray detectors
This article concerns optimization methods for data analysis for the X-ray GEM detector system. The offline analysis of collected samples was optimized for MATLAB computations. Compiled functions in C language were used with MEX library. Significant speedup was received for both ordering-preprocessing and for histogramming of samples. Utilized techniques with obtained results are presented.
KEYWORDS: Field programmable gate arrays, Data acquisition, X-rays, Diagnostics, Data processing, Signal processing, Data storage, Computer simulations, Detection and tracking algorithms, Sensors
Soft X-ray (SXR) measurement systems working in tokamaks or with laser generated plasma can expect high photon fluxes. Therefore it is necessary to focus on data processing algorithms to have the best possible efficiency in term of processed photon events per second. This paper refers to recently designed algorithm and data-flow for implementation of charge data acquisition in FPGA. The algorithms are currently on implementation stage for the soft X-ray diagnostics system. In this paper despite of the charge processing algorithm is also described general firmware overview, data storage methods and other key components of the measurement system. The simulation section presents algorithm performance and expected maximum photon rate.
KEYWORDS: Field programmable gate arrays, Data acquisition, Sensors, Detection and tracking algorithms, Telecommunications, Data communications, Data transmission, Data storage, MATLAB, Data processing
This article proposes new method of storing data and transferring it to PC in the X-ray GEM detector system. The whole process is performed by FPGA chips (Spartan-6 series from Xilinx). Comparing to previous methods, new approach allows to store much more data in the system. New, improved implementation of the communication algorithm significantly increases transfer rate between system and PC. In PC data is merged and processed by MATLAB. The structure of firmware implemented in the FPGAs is described.
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