This work discusses different approaches to data processing in measurement systems with their examples. An overview of dedicated hardware to software migration trends is presented. Software data processing for soft real-time measurement systems is described based on multiple characteristics. A significant part of this work relates to an analysis of different frameworks which can be used in such systems to implement parts dedicated to software processing. Finally, the exemplary system, which can benefit from chosen solutions, built by our group is presented.
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 Gas Electron Multiplier (GEM) is a detector used to register ionizing radiation, e.g., soft X-rays. The detector of this type, built and developed at the IPPLM institute, allows registering X-rays in the energy range of 2-20keV and determining its intensity in time, as well as its spatial position and energy. Simulating the work of such a detector, performed in parallel to experimental research, and sometimes preceding it, allows for optimization of construction and operation parameters of this detector with respect to the requirements set in the experiment, and allows for a better understanding of the physical processes occurring in the detector. The paper presents how simulations are performed, i.e. describes applied programs, main stages of simulation such as the construction of a three-dimensional model of the detector for calculations, the efficiency of X-ray detection, its conversion to primary electrons and the process of avalanche formation. Finally, the results obtained in this way are also presented.
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.
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.
Many types of micropattern gas detectors (MPGD) have been used as tracking detectors in experiments with high-energy particle physics and imaging detectors, especially in the case of soft X-rays. Several advantages like high count rate capability, good spatial and energy resolution, low cost and possibility of constructing large area detectors with very small dead area make these detectors very attractive in field of particle physics. The paper presents the designing, construction and assembling of two prototype Triple Gas Electron Multiplier (Triple-GEM) detectors. These were developed for highresolution X-ray spectroscopy measurements for tokamak plasma to serve as plasma monitoring in soft X-ray region for the WEST tokamak.
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.
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.
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.
KEYWORDS: Data modeling, Field programmable gate arrays, Data acquisition, Systems modeling, Sensors, Signal detection, Data communications, Diagnostics, Data processing, Control systems, Plasma diagnostics
Modern physics experiments require construction of advanced, modular measurement systems for data processing and registration purposes. The most important systems are connected to the feedback loop in order to perform real-time experiment control. The paper is related to soft X-ray measurement systems working on tokamaks. As the sensor unit the GEM detector is considered. The hardware platform consists of analog and digital data path, with data preprocessing in FPGAs and real-time output products computation in embedded PC (CPU). The main focus in put on the importance of output products data quality from the measurement systems. In the paper is presented the model of the data evaluation and quality monitoring component for work in real-time. The typical hardware and data path structure is described, with analysis of the low-quality data propagation, in order to present the most optimal placement of the DQM data filtering structure. The DQM model is divided into the FPGA and CPU part. The model is based on iterative signal classification unit working in real-time. Additional sub-diagnostics allows recording and analysis of the events in term of raw data and statistical information. In a summary section the benefits from model implementation are described. The presented model is designed in universal, modular approach and can be applied to various measurement systems.
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.
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, 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.
KEYWORDS: Data modeling, Sensors, Field programmable gate arrays, Systems modeling, Data processing, Data communications, Data acquisition, Data storage, Computing systems, Control systems
Modern physics experiments requires construction of advanced, modular measurement systems for data processing and
registration purposes. Components are often designed in one of the common mechanical and electrical standards,
e.g. VME or uTCA. The paper is focused on measurement systems using FPGAs as data processing blocks, especially
for plasma diagnostics using GEM detectors with data quality monitoring aspects. In the article is proposed standardized
model of HDL FPGA firmware implementation, for use in a wide range of different measurement system. The effort was
made in term of flexible implementation of data quality monitoring along with source data dynamic selection. In the
paper is discussed standard measurement system model followed by detailed model of FPGA firmware for modular
measurement systems. Considered are both: functional blocks and data buses. In the summary, necessary blocks and
signal lines are described. Implementation of firmware following the presented rules should provide modular design,
with ease of change different parts of it. The key benefit is construction of universal, modular HDL design, that can be
applied in different measurement system with simple adjustments.
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: 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.
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.
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).
Various types of Micro Pattern Gas Detectors (MPGDs) found applications as tracking detectors in high energy particle physics experiments and as well as imaging detectors, especially for soft X-rays. These detectors offer several advantages like high count rate capability, good spatial and energy resolution, low cost and possibility of constructing large area detectors with very small dead area. Construction, like the triple Gas Electron Multiplier (GEM) detector has become a standard detector, which is widely used for different imaging applications. Some examples of such applications are: monitoring the impurity in plasma, imaging system for mapping of some parameters like pigment distributions using X-ray fluorescence technique[1], proton range radiography system for quality assurance in hadron therapy. Measuring of the Soft X-Ray (SXR) radiation of magnetic fusion plasma is a standard way of accessing valuable information, for example, about particle transport and MHD. The paper is focused on the design of GEM based soft Xray radiation detecting system which is under development. It is dedicated to study soft X-ray emission of plasma radiation with focus on tungsten emission lines energy region. The paper presents the designing, construction and assembling of a prototype of two triple-GEM detectors for soft-X ray application on the WEST device.
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: 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 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.
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: 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.
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.
The detecting devices dedicated for plasma monitoring will be exposed for massive fluxes of neutron, photons as well as other rays that are components of fusion reactions and their product interactions with plasma itself or surroundings. In result detecting module metallic components will be activated becoming a source of radiation. Moreover, electronics components could change their electronic properties. The prototype GEM detector constructed for monitoring soft X-ray radiation in ITER oriented tokamaks was used for plasma monitoring during experimental campaign on tokamak ASDEX Upgrade. After that it became a source of gamma radiation caused by neutrons. The present work contains description of detector activation in the laboratory conditions.
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: 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.
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, Field programmable gate arrays, Plasma, Imaging systems, Data acquisition, Signal detection, Calibration, Analog electronics, Single photon, X-rays
A novel approach to two dimensional Gas Electron Multiplier (GEM) detector readout is presented. Unlike
commonly used methods, based on discriminators and analogue FIFOs, the method developed uses simulta-
neously sampling high speed ADCs with fast hybrid integrator and advanced FPGA-based processing logic to
estimate the energy of every single photon. Such a method is applied to every GEM strip / pixel signal. It is
especially useful in case of crystal-based spectrometers for soft X-rays, 2D imaging for plasma tomography and
all these applications where energy resolution of every single photon is required. For the purpose of the detector
readout, a novel, highly modular and extendable conception of the measurement platform was developed. It is
evolution of already deployed measurement system for JET Spectrometer.
This article debates about data fast acquisition and histogramming method for the X-ray GEM detector. The whole
process of histogramming is performed by FPGA chips (Spartan-6 series from Xilinx). The results of the histogramming
process are stored in an internal FPGA memory and then sent to PC. In PC data is merged and processed by MATLAB.
The structure of firmware functionality implemented in the FPGAs is described. Examples of test measurements and
results are presented.
KEYWORDS: Sensors, Data acquisition, Calibration, X-rays, Signal detection, Data processing, Fusion energy, Plasma, X-ray detectors, Field programmable gate arrays
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 [1]. Multi-channel measurement system and essential data processing for X-ray energy and position recognition is consider. Several modes of data acquisition are introduced depending on processing division for hardware and software components. Typical measuring issues aredeliberated for enhancement of data quality. Fundamental output characteristics are presented for one and two dimensional detector structure. Representative results for reference X-ray source and tokamak plasma are demonstrated.
Presented 2D gaseous detector system has been developed and designed to provide energy resolved fast dynamic plasma radiation imaging in the soft X-Ray region with 0.1 kHz exposure frequency for online, made in real time, data acquisition (DAQ) mode. The detection structure is based on triple Gas Electron Multiplier (GEM) amplification structure followed by the pixel readout electrode. The efficiency of detecting unit was adjusted for the radiation energy region of tungsten in high-temperature plasma, the main candidate for the plasma facing material for future thermonuclear reactors. Here we present preliminary laboratory results and detector parameters obtained for the developed system. The operational characteristics and conditions of the detector were designed to work in the X-Ray range of 2-17 keV. The detector linearity was checked using the fluorescence lines of different elements and was found to be sufficient for good photon energy reconstruction. Images of two sources through various screens were performed with an X-Ray laboratory source and 55Fe source showing a good imaging capability. Finally offline stream-handling data acquisition mode has been developed for the detecting system with timing down to the ADC sampling frequency rate (~13 ns), up to 2.5 MHz of exposure frequency, which could pave the way to invaluable physics information about plasma dynamics due to very good time resolving ability. Here we present results of studied spatial resolution and imaging properties of the detector for conditions of laboratory moderate counting rates and high gain.
KEYWORDS: Sensors, Data acquisition, Control systems, Electronics, Plasma, Telecommunications, Data processing, Diagnostics, Calibration, Double positive medium
This paper presents the system integrating the dedicated measurement and control electronic systems for Gas Electron Multiplier (GEM) detectors with the Control and Data Acquisition system (CODAS) in the JET facility in Culham, England. The presented system performs the high level procedures necessary to calibrate the GEM detector and to protect it against possible malfunctions or dangerous changes in operating conditions. The system also allows control of the GEM detectors from CODAS, setting of their parameters, checking their state, starting the plasma measurement and to reading the results. The system has been implemented using the Python language, using the advanced libraries for implementation of network communication protocols, for object based hardware management and for data processing.
This paper describes architecture of a new data acquisition system (DAQ) targeted mainly at plasma diagnostic experiments. Modular architecture, in combination with selected hardware components, allows for straightforward reconfiguration of the whole system, both offline and online. Main emphasis will be put into the implementation of data transmission subsystem in said system. One of the biggest advantages of described system is modular architecture with well defined boundaries between main components: analog frontend (AFE), digital backplane and acquisition/control software. Usage of a FPGA chips allows for a high flexibility in design of analog frontends, including ADC ↔ FPGA interface. Data transmission between backplane boards and user software was accomplished with the use of industry-standard PCI Express (PCIe) technology. PCIe implementation includes both FPGA firmware and Linux device driver. High flexibility of PCIe connections was accomplished due to use of configurable PCIe switch. Whenever it's possible, described DAQ system tries to make use of standard off-the-shelf (OTF) components, including typical x86 CPU & motherboard (acting as PCIe controller) and cabling.
This paper describes current status of electronics, firmware and software development for new plasma measurement
system for use in WEST facility. The system allows to perform two dimensional plasma visualization (in time) with
spectrum measurement. The analog front-end is connected to Gas Electron Multiplier detector (GEM detector).
The system architecture have high data throughput due to use of PCI-Express interface, Gigabit Transceivers and
sampling frequency of ADC integrated circuits. The hardware is based on several years of experience in building X-ray
spectrometer system for Joint European Torus (JET) facility. Data streaming is done using Artix7 FPGA devices.
The system in basic configuration can work with up to 256 channels, while the maximum number of measurement
channels is 2048. Advanced firmware for the FPGA is required in order to perform high speed data streaming and analog
signal sampling. Diagnostic system management has been developed in order to configure measurement system, perform
necessary calibration and prepare hardware for data acquisition.
KEYWORDS: Diagnostics, Field programmable gate arrays, Plasma systems, Plasma, Data storage, Sensors, Telecommunications, Data communications, Tungsten, Analog electronics
This paper describes the concept of data management software for the multichannel readout system for the GEM
detector used in WEST Plasma experiment. The proposed system consists of three separate communication
channels: fast data channel, diagnostics channel, slow data channel. Fast data channel is provided by the FPGA
with integrated ARM cores providing direct readout data from Analog Front Ends through 10GbE with short,
guaranteed intervals. Slow data channel is provided by multiple, fast CPUs after data processing with detailed
readout data with use of GNU/Linux OS and appropriate software. Diagnostic channel provides detailed feedback
for control purposes.
KEYWORDS: Sensors, Field programmable gate arrays, Control systems, Data acquisition, Calibration, Operating systems, Computing systems, Diagnostics, Power supplies, Reliability
This paper describes the embedded controller used for the multichannel readout system for the GEM detector. The controller is based on the embedded Mini ITX mainboard, running the GNU/Linux operating system. The controller offers two interfaces to communicate with the FPGA based readout system. FPGA configuration and diagnostics is controlled via low speed USB based interface, while high-speed setup of the readout parameters and reception of the measured data is handled by the PCI Express (PCIe) interface. Hardware access is synchronized by the dedicated server written in C. Multiple clients may connect to this server via TCP/IP network, and different priority is assigned to individual clients. Specialized protocols have been implemented both for low level access on register level and for high level access with transfer of structured data with "msgpack" protocol. High level functionalities have been split between multiple TCP/IP servers for parallel operation. Status of the system may be checked, and basic maintenance may be performed via web interface, while the expert access is possible via SSH server. System was designed with reliability and flexibility in mind.
KEYWORDS: Field programmable gate arrays, Sensors, X-rays, Photons, X-ray detectors, Signal detection, Signal processing, Calibration, Time metrology, Electronics
This article presents a fast charge histogramming method for the position sensitive X-ray GEM detector. The energy
resolved measurements are carried out simultaneously for 256 channels of the GEM detector. The whole process of
histogramming is performed in 21 FPGA chips (Spartan-6 series from Xilinx) . The results of the histogramming process
are stored in an external DDR3 memory. The structure of an electronic measuring equipment and a firmware
functionality implemented in the FPGAs is described. Examples of test measurements are presented.
KEYWORDS: Sensors, Field programmable gate arrays, Amplifiers, X-rays, Signal detection, Connectors, Clocks, Temperature metrology, Analog electronics, Calibration
A novel approach to the Gas Electron Multiplier1 (GEM) detector readout is presented. Unlike commonly used
methods, based on discriminators, and analogue FIFOs,[ the method developed uses simultaneously sampling
high speed ADCs and advanced FPGA-based processing logic to estimate the energy of every single photon.
Such method is applied to every GEM strip signal. It is especially useful in case of crystal-based spectrometers
for soft X-rays, where higher order reflections need to be identified and rejected. For the purpose of the detector
readout, a novel conception of the measurement platform was developed.
KEYWORDS: Sensors, Field programmable gate arrays, Electronics, Signal detection, Prototyping, X-rays, Amplifiers, Signal processing, Diagnostics, Power supplies
A novel approach to the Gas Electron Multiplier (GEM) detector readout is presented. Unlike commonly used methods, based on discriminators[2],[3] and analogue FIFOs[1], the method developed uses simultaneously sampling high speed ADCs and advanced FPGA-based processing logic to estimate the energy of every single photon. Such method is applied to every GEM strip signal. It is especially useful in case of crystal-based spectrometers for soft X-rays, where higher order reflections need to be identified and rejected[5].
KEYWORDS: Signal processing, Field programmable gate arrays, Linear filtering, Sensors, Signal detection, Electronic filtering, Amplifiers, Silicon, Analog electronics, Prototyping
This paper presents analysis of processing method of the signal from Gas Electron Multiplier (GEM) detector acquired in
our Field-Programmable Gate Array (FPGA) based readout system. We have found that simple processing of GEM signal
received from the charge amplifier, sampled at 100MHz with 10-bit resolution, after low-pass filtering with 15 MHz cut-off
frequency, provides accuracy similar to obtained by processing of the raw GEM signal sampled at 2.5 GHz frequency with
8-bit resolution. Even when 3 bits are lost due to long term instability of the detector and analog part of the system - resulting
in 7-bit effective resolution, the reasonable accuracy is still preserved. Additionally we have analyzed computational
power required to perform the real-time analysis of the GEM signal, taking into consideration resources offered by the
FPGA chip used in the prototype platform.
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