Paweł Linczuk

Evaluation of FPGA to PC feedback loop

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.

Algorithm for fast event parameters estimation on GEM acquired data

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.

The computation in diagnostics for tokamaks: systems, designs, approaches

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.

Development of GEM detector for plasma diagnostics application: simulations addressing optimization of its performance

The advanced Soft X-ray (SXR) diagnostics setup devoted to studies of the SXR plasma emissivity is at the moment a highly relevant and important for ITER/DEMO application. Especially focusing on the energy range of tungsten emission lines, as plasma contamination by W and its transport in the plasma must be understood and monitored for W plasma-facing material. The Gas Electron Multiplier, with a spatial and energy-resolved photon detecting chamber, based SXR radiation detection system under development by our group may become such a diagnostic setup considering and solving many physical, technical and technological aspects. This work presents the results of simulations aimed to optimize a design of the detectors internal chamber and its performance. The study of the effect of electrodes alignment allowed choosing the gap distances which maximizes electron transmission and choosing the optimal magnitudes of the applied electric fields. Finally, the optimal readout structure design was identified suitable to collect a total formed charge effectively, basing on the range of the simulated electron cloud at the readout plane which was in the order of ~ 2 mm.

The software-defined fast post-processing for GEM soft x-ray diagnostics in the Tungsten Environment in Steady-state Tokamak thermal fusion reactor

This article presents a novel software-defined server-based solutions that were introduced in the fast, real-time computation systems for soft X-ray diagnostics for the WEST (Tungsten Environment in Steady-state Tokamak) reactor in Cadarache, France. The objective of the research was to provide a fast processing of data at high throughput and with low latencies for investigating the interplay between the particle transport and magnetohydrodynamic activity. The long-term objective is to implement in the future a fast feedback signal in the reactor control mechanisms to sustain the fusion reaction. The implemented electronic measurement device is anticipated to be deployed in the WEST. A standalone software-defined computation engine was designed to handle data collected at high rates in the server back-end of the system. Signals are obtained from the front-end field-programmable gate array mezzanine cards that acquire and perform a selection from the gas electron multiplier detector. A fast, authorial library for plasma diagnostics was written in C++. It originated from reference offline MATLAB implementations. They were redesigned for runtime analysis during the experiment in the novel online modes of operation. The implementation allowed the benchmarking, evaluation, and optimization of plasma processing algorithms with the possibility to check the consistency with reference computations written in MATLAB. The back-end software and hardware architecture are presented with data evaluation mechanisms. The online modes of operation for the WEST are discussed. The results concerning the performance of the processing and the introduced functionality are presented.

GPU implementation of multiline TRL calibration for efficient Monte-Carlo uncertainty analysis

We present a graphics-processing-unit (GPU) OpenCL implementation of the multiline through-reflect-line (TRL) algorithm of vector-network-analyzer (VNA) calibration. We obtained about 40× of speed improvement on a middle-end GPU as compared to a single-threaded C/C++ implementation. This speed improvement leads to a significant acceleration of VNA-measurement Monte-Carlo uncertainty analysis, making it possible to evaluate VNA measurement uncertainties in a timeframe of a few minutes.

2D GEM based imaging detector readout capabilities from perspective of intense soft x-ray plasma radiation

A detecting system based on the Gas Electron Multiplier (GEM) technology is considered for tokamak plasma radiation monitoring. In order to estimate its capabilities in processing and recording intense photon flux (up to ∼0.1 MHz/mm2), the imaging effectiveness of GEM detectors was tested with different patterned anode planes (i.e., different signal readouts): a simple hexagonal readout structure and three structures with interconnected electrodes (XY square, XY rectangular, and UXV). It was found that under intense photon flux, all the readouts fail to account for a considerable amount of the incoming signals due to mostly photon position determination ambiguity and overlapped signals. Analysis of the signals that can be used to determine photon position and energy unambiguously showed that the UXV readout structure is more effective among the readouts with interconnected electrodes. Along with similar spatial resolution and accuracy, the UXV based layout could be considered as a quite promising base of the interconnected anode electrodes configuration, keeping in mind that the photon rate capability has to be improved for the final application.

Data distribution and dispatching software for processing measurement data acquired with SXR GEM-based system

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.

Matlab-based modeling of GEM diagnostic data sequencer

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 methodology of development of real-time and high-throughput heterogeneous devices for plasma confinement fusion diagnostics

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.