Accelerator System Research Articles

Enabling Fast and Memory-Efficient Acceleration for Pattern Matching Workloads: The Lightweight Automata Processing Engine

Growing pattern matching applications are employing finite automata as their basic processing model. These applications match tens to thousands of patterns on a large amount of data, which brings a great challenge to conventional processors. Therefore hardware-based solutions have emerged frequently and achieved high throuphput automata processing. However, existing methods are generally difficult to achieve both processing speed and storage efficiency, and are often too heavy to be integrated into a small chip and have to rely on off-chip DRAMs or other high capacity memories even on some simple data sets, leading to the potential area and power consumption issues. In this paper, we focus on building a more lightweight automata processing engine, hoping to store the whole automata model into on-chip memory and run effectively and independently. We propose LAP, a lightweight automata processing engine. Powered with a novel automata model (A-DFA) and efficient packing algorithms, extremely high storage efficiency compared with traditional DFA is achieved in LAP. Meanwhile, we identify the key parallelization factors in the A-DFA model and then propose a specialized microarchitecture with novel instructions to further accelerate the state transition process. As a result, LAP can obtain more effective trade-off between processing speed and storage efficiency. Evaluation results show that LAP achieves extremely high storage efficiency on simple data sets, exceeding IBM's RegX by 8×, and achieves significant improvements in processing speed ranging from 1.32× to 1.91× compared with previous lightweight hardware implementations. Moreover, LAP has good scalability in hardware architecture. It is easy to build an acceleration system with higher throughput by increasing the number of cores. We prototype a 16-core system into Xilinx ZC702 FPGA and a 64-core system into Xilinx ZCU102 FPGA respectively. The prototype system on ZC702 on average achieves 3.5 GB/s throughput on simple data sets, and the prototype system on ZCU102 can obtain higher throughput and compute density values on part of large datasets in ANMLZoo compared with modern in-memory NFA-based solutions.

Ion-Beam Surface Modification of Carbon Fibers

Carbon fibers are used in the production of automobiles, airplanes, sporting goods, energy, and biomedicine due to their unique properties such as high specific strength, high specific tensile strength, low coefficient of thermal expansion, and low density. The research and development of both the technology of carbon fibers production and their modification for a wide range of applications have been and remain relevant. The summary of the accumulated experience in the modification of carbon fibers shows that ion-beam treatment allows to obtain a variety of geometry of the developed surface topography, in particular, whisker-shaped and corrugated oriented across or along the fiber. Such processing compares favorably with ordinary fiber whiskering both by a variety of geometry of the composite interface, and by the absence of the problem of whisker-fiber adhesion. Ion-beam treatment also makes it possible to modify the surface layer structure from amorphized to ordered with different degrees of graphitization. Irradiation with chemically active ions leads to functionalization of carbon fiber due to formation, for example, of nitrides and carbon oxides. The choice of nitrogen ions for the technology of carbon-carbon and carbon-ceramic composites seems to be more preferable due to less stringent requirements for the temperature of the irradiated fiber. For ion-beam corrugation of polyacrylonitrile-based carbon fiber surface, only its heating above the temperature of dynamic annealing of radiation damage is required. The use of helium ions in technological plasma acceleration systems leads to a significant efficiency increase in ion-beam processing.

Upgrades of a Small Electrostatic Dust Accelerator at the University of Stuttgart

In this paper, we describe the upgrade of a small electrostatic dust accelerator located at the University of Stuttgart. The newly developed dust source, focusing lens, differential detector and linac stage were successfully installed and tested in the beam line. The input voltage range of the dust source was extended from 0–20 kV to 0–30 kV. A newly developed dust detector with two differential charge sensitive amplifiers is employed to monitor particles with speeds from several m/s to several km/s and with surface charges above 0.028 fC. The post-stage linac provides an additional acceleration ability with a total voltage of up to 120 kV. The entire system of this dust accelerator works without protection gas and without a complex high voltage terminal. The volumes to be pumped down are small and can be quickly evacuated. The new system was used to accelerate micron- and submicron-sized metal particles or coated mineral materials. Improvements in the acceleration system allow for a wider variety of dust materials and new applications.

Orbital angular momentum detection device for vortex microwave photons

Orbital angular momentum (OAM), which was first discovered in the optical field, represents a new dimension of electromagnetic waves. However, the detection of OAM microwave photons, i.e., vortex microwave photons, at room temperature is difficult due to their low energy. Here we report a prototype of a vortex microwave photon detection device based on vortex electrons. Our OAM detection device efficiently distinguishes the intrinsic OAM in the microwave band, which is helpful for exploring new physical dimensions. In addition, the detection device can be enhanced with a vortex electron sorting device designed with electron holograms so that OAM microwave photon demultiplexing can be achieved. Finally, the OAM detection device has high practicability; i.e., not only it can be used at room temperature, but also it is much smaller than a particle accelerator system. To illustrate the significance of this method, we demonstrate an on-off keying transmission system based on our OAM detection device.

Simulated Adaptive Radiotherapy for Shrinking Glioblastoma Resection Cavities on a Hybrid MRI-Linear Accelerator.

During radiation therapy (RT) of glioblastoma, daily MRI with combination MRI-linear accelerator (MRI-Linac) systems has demonstrated significant anatomic changes, including evolving post-surgical cavity shrinkage. Cognitive function RT for brain tumors is correlated with radiation doses to healthy brain structures, especially the hippocampi. Therefore, this study investigates whether adaptive planning to the shrinking target could reduce normal brain RT dose with the goal of improving post-RT function. We evaluated 10 glioblastoma patients previously treated on a 0.35T MRI-Linac with a prescription of 60 Gy delivered in 30 fractions over six weeks without adaptation ("static plan") with concurrent temozolomide chemotherapy. Six weekly plans were created per patient. Reductions in the radiation dose to uninvolved hippocampi (maximum and mean) and brain (mean) were observed for weekly adaptive plans. The dose (Gy) to the hippocampi for static vs. weekly adaptive plans were, respectively: max 21 ± 13.7 vs. 15.2 ± 8.2 (p = 0.003) and mean 12.5 ± 6.7 vs. 8.4 ± 4.0 (p = 0.036). The mean brain dose was 20.6 ± 6.0 for static planning vs. 18.7 ± 6.8 for weekly adaptive planning (p = 0.005). Weekly adaptive re-planning has the potential to spare the brain and hippocampi from high-dose radiation, possibly reducing the neurocognitive side effects of RT for eligible patients.

An Energy-and-Area-Efficient CNN Accelerator for Universal Powers-of-Two Quantization

CNN model computation on edge devices is tightly restricted to the limited resource and power budgets, which motivates the low-bit quantization technology to compress CNN models into 4-bit or lower format to reduce the model size and increase hardware efficiency. Most current low-bit quantization methods use uniform quantization that maps weight and activation values onto evenly-distributed levels, which usually results in accuracy loss due to distribution mismatch. Meanwhile, some non-uniform quantization methods propose specialized representation that can better match various distribution shapes but are usually difficult to be efficiently accelerated on hardware. In order to achieve low-bit quantization with high accuracy and hardware efficiency, this paper proposes Universal Power-of-Two (UPoT), a novel low-bit quantization method that represents values as the addition of multiple power-of-two values selected from a series of subsets. By updating the subset contents, UPoT can provide adaptive quantization levels for various distributions. For each CNN model layer, UPoT automatically searches for the optimized distribution that minimizes the quantization error. Moreover, we design an efficient accelerator system with specifically optimized power-of-two multipliers and requantization units. Evaluations show that the proposed architecture can provide high-performance CNN inference with reduced circuit area and energy, and outperforms several mainstream CNN accelerators with higher ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8\times $ </tex-math></inline-formula> – <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$65\times $ </tex-math></inline-formula> ) area efficiency and ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times $ </tex-math></inline-formula> – <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$19\times $ </tex-math></inline-formula> ) energy efficiency. Further experiments of 4/3/2-bit quantization on ResNet18/50, MobileNet_V2 and EfficientNet models show that our UPoT can achieve high model accuracy which greatly outperform other state-of-the-art low-bit quantization methods by 0.3%–6%. The results indicate that our approach provides a highly-efficient accelerator for low-bit CNN model quantization with low hardware overheads and good model accuracy.

Hardware acceleration of number theoretic transform for zk‐SNARK

AbstractZk‐SNARK unleashes the great potential of ZKP (zero‐knowledge proof) in the blockchain, distributed storage, and so forth. However, the proof‐generation of zk‐SNARK is excessively time intensive, making it a challenge to deploy a high‐performance zk‐SNARK in most real applications. As a result, NTT (Number Theoretic Transform), one of the most time‐consuming parts in proof‐generation, needs to be accelerated significantly. To address this issue, we propose a novel and efficient “data reordering" technique to enable a highly pipelined architecture, on which an FPGA‐based hardware accelerator is designed to support the large‐bitwidth and large‐scale NTT tasks in zk‐SNARK. This two‐level pipelined architecture can effectively reduce the data dependency and memory access requirements, meanwhile, can be flexibly scaled to different scales of FPGAs. To balance computing efficiency and flexibility, the OpenCL equipped with HLS is used to implement the heterogeneous acceleration system. We prototype the accelerator on the AMD‐Xilinx Alveo U50 card (UltraScale+ XCU50 FPGA). The evaluation results show that (1) our accelerator shows high scalability for different scales of FPGAs with a stable performance improvement; (2) it performs 1.95 faster than the one in PipeZK; (3) and it achieves 27.98 , 1.74 speedup and 6.9 , 6 energy efficiency improvement than AMD Ryzen 9 5900X single core and 12 cores respectively when integrated into the well‐known ZKP open‐source project, Bellman.

Preparation and acceleration mechanism of a ternary hardening accelerator for high-performance concrete with full aeolian sand

The application of aeolian sand to produce concrete for the engineering construction of desert areas has important significance. Preliminary studies have suggested that producing high-performance concrete with full aeolian sand (FA-HPC) is feasible. However, construction in desert areas is often the most vulnerable to harsh climatic conditions. Hence, there is a need to investigate how to accelerate the strength formation of aeolian sand concrete to reduce the negative impact of the environment on its early performance development. In this paper, the applicability of a combination of aluminum sulfate (Al2(SO4)3), sodium nitrate (NaNO3), and triethanolamine (TEA) as a ternary hardening accelerator for FA-HPC was investigated. The response surface methodology (RSM) was employed to optimize the combination of the ternary hardening accelerator. The microscopic morphology and chemical composition before and after the addition of the accelerator were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. Then, the accelerated hydration mechanism was analyzed and a hydration model was established. The results showed that the addition of the ternary hardening accelerator significantly improved the early strength of aeolian sand concrete. The optimal dose combination of the accelerator is 0.93% for Al2(SO4)3, 1.29% for NaNO3, and 0.03% for TEA based on the response surface methodology (RSM). The incorporation of the accelerator increases the 12-hour and 1-day flexural strength of FA-HPC by 48.6% and 25.8%, respectively. In the ternary hardening accelerator system, NaNO3 and TEA enhance the dissolution of the mineral phase and provide a better environment for the hydration reaction. Meanwhile, the accelerator modifies the morphology of the hydration products and contributes to the strength skeleton formation. In addition, more ettringites (AFt) were formed in the effect of the ternary hardening accelerator, which improved the early mechanical properties of FA-HPC. The research results could promote the engineering application of FA-HPC in desert areas and provide theoretical guidance for the rapid construction and repair of the project.

AINNS: All-Inclusive Neural Network Scheduling Via Accelerator Formalization

Driven by the rapid development of accelerators and diverse efficiency requirements of the naturally heterogeneous neural network computation, recent years have seen increased heterogeneity in neural network accelerator systems in terms of network structures, accelerator dataflows and implementations. However, existing research fails to schedule and map the heterogeneous neural networks on heterogeneous accelerators efficiently. They rely on clumpy exhaustive search or complicated ad hoc mapping approaches due to the semantic gap between the networks and accelerators. This paper proposes a systematic method to transform various accelerators into standard parameterized containers of the neural network loops, which builds a direct connection between the computation and the underlying hardware resources. This enables us to match the neural networks with accelerators based on their essential characteristics (e.g., reuse opportunities and bandwidth requirements) without diving into the detailed architectures. To this end, we propose AINNS, an all-inclusive neural network scheduler, that automatically schedules and maps the NN computation on heterogeneous accelerators with just one universal algorithm. Our experimental results show the proposed AINNS not only performs well in the traditional neural network acceleration but also improves the system throughput and energy efficiency by 1.8x and 1.7x respectively in the most challenging heterogeneous acceleration system.

Application of a Comprehensive Treatment Planning Test for Credentialing Intensity-Modulated Radiotherapy and RapidArc in a TrueBeam Linear Accelerator Setup.

An extended version of task group report (TG)-119 dosimetric tests was introduced and tested on the TrueBeam linear accelerator setup. Treatment plan results and quality assurance (QA) results of RapidArc (RA) and intensity-modulated radiotherapy (IMRT) were compared to understand the limitation and efficacy of the RA and IMRT system of the linear accelerator. Test structure sets were drawn on OCTAVIUS four-dimensional (4D) phantom computed tomography scan data for this study. We generated treatment plans based on the specified goal in the Eclipse™ treatment planning system using RA and IMRT in the study phantom. We used the same planning objectives for RA and IMRT techniques. Planar dose verification was performed using electronic portal imaging device and OCTAVIUS 4D phantom. The treatment log file was further analyzed using Pylinac (V2.4.0 (Open Source Code library available on Github, runs under Python programming language)) to compare the dosimetric outcome of RA and IMRT. Dose to the planning target volume (PTV) 1-5 and organ at risk (OAR) were analyzed in this study for the efficiency comparison of RA and IMRT. The primary objective was accomplished by adhering to the dose constraints associated with PTV 2 and the OAR. RA and IMRT also met the secondary objective. The tertiary goal of dose delivery to PTV 4 was met with RA but not IMRT. This study can be utilized to compare different institutions' planning and patient-specific QA (PSQA) procedures. The findings of this study were in line with the published works of the literature. A multi-institutional planning and delivery accuracy audit can be built using this structure and set of planning objectives having similar PSQA phantom. The TG-119 report incorporated test challenges that were combined in a single study set and a single plan. This reduces the complexity of performing the original TG-119 tests, whereas keeping the challenges as introduced in the TG-119 report. This study's planning and dosimetric results could be further utilized for dosimetry audit with any institute having a linear accelerator and OCTAVIUS 4D phantom for PSQA.

Effect of the Flat-Top Resonance System of DC-280 Accelerator on a Charged Particle Beam

Effect of the Flat-Top Resonance System of DC-280 Accelerator on a Charged Particle Beam

The Implementation and Optimization of Neuromorphic Hardware for Supporting Spiking Neural Networks With MLP and CNN Topologies

Spiking neural network (SNN) has attracted extensive attention in large-scale image processing tasks. To obtain higher computing efficiency, the development of hardware architecture suitable for SNN computing has become a hot research topic. However, the existing hardware of spike neurons still has high computational complexity and they do not perform well enough on complicated datasets, and the neuromorphic system cannot support SNNs with different convolutional topologies, resulting in low efficiency of the system. To address the above problems, an optimized leaky integrated-and-fire (LIF) neuron called EPC-LIF and a neuromorphic hardware acceleration system (ELIF-NHAS) are designed and implemented based on the field-programmable gate array (Xilinx Kintex-7). First, the classical LIF neuron is designed using the optimization method of extended prediction correction (EPC), which can reduce the computation complexity and hardware resources with a maximum frequency of 439.95 MHz. The ELIF-NHAS is constructed and optimized with parallel and pipeline techniques for effectively running SNNs, working with a maximum frequency of 135.6 MHz. Then, the genetic algorithm is applied to adjust the membrane threshold of neurons for further improving the accuracy of SNNs. Furthermore, the ELIF-NHAS can support different SNNs with multilayer perceptron and convolutional neural network topologies (called SCNN), including traditional, depth-separate, and residual convolutions. The accuracy of multilayer SCNNs can achieve 99.10%, 90.29%, and 82.15% on MNIST, Fashion-MNIST, and SVHN datasets, respectively; and the speed and energy consumption achieve 1.21 ms/image and 1.19 mJ/image. Compared with existing systems, the ELIF-NHAS is more suitable for the deployment and inference of SNNs with higher speed and lower consumption.

First benchmarked electron cooling simulations from first principles

We present the first microscopic electron cooling simulations from first principles with accurate prediction of cooling time. These simulations were performed using our previously developed numerical method, PHAD, which is the first efficient large-scale collisional numerical method in beam physics. The simulation results are benchmarked with the experimental data of the low energy bunched electron cooling of ion beams at the storage ring CSRm at the IMP facility in China. We have accurately considered the nonlinear dynamics in the whole accelerator system in addition to the electron cooling section. As a result, our simulations correctly reproduced cooling times of the experiments from first principles and without any tuning or fitting parameters in the code.

Thoracic motion-compensated cone-beam computed tomography in under 20 seconds on a fast-rotating linac: A simulation study.

Rapid kV cone-beam computed tomography (CBCT) scans are achievable in under 20 s on select linear accelerator systems to generate volumetric images in three dimensions (3D). Daily pre-treatment four-dimensional CBCT (4DCBCT) is recommended in image-guided lung radiotherapy to mitigate the detrimental effects of respiratory motion on treatment quality. To demonstrate the potential for thoracic 4DCBCT reconstruction using projection data that was simulated using a clinical rapid 3DCBCT acquisition protocol. We simulated conventional (1320 projections over 4 min) and rapid (491 projections over 16.6 s) CBCT acquisitions using 4D computed tomography (CT) volumes of 14 lung cancer patients. Conventional acquisition data were reconstructed using the 4D Feldkamp-Davis-Kress (FDK) algorithm. Rapid acquisition data were reconstructed using 3DFDK, 4DFDK, and Motion-Compensated FDK (MCFDK). Image quality was evaluated using Contrast-to-Noise Ratio (CNR), Tissue Interface Width (TIW), Root-Mean-Square Error (RMSE), and Structural SIMilarity (SSIM). The conventional acquisition 4DFDK reconstructions had median phase averaged CNR, TIW, RMSE, and SSIM of 2.96, 8.02mm, 83.5, and 0.54, respectively. The rapid acquisition 3DFDK reconstructions had median CNR, TIW, RMSE, and SSIM of 2.99, 13.6mm, 112, and 0.44 respectively. The rapid acquisition MCFDK reconstructions had median phase averaged CNR, TIW, RMSE, and SSIM of 2.98, 10.2mm, 103, and 0.46, respectively. Rapid acquisition 4DFDK reconstruction quality was insufficient for any practical use due to sparse angular projection sampling. Results suggest that 4D motion-compensated reconstruction of rapid acquisition thoracic CBCT data are feasible with image quality approaching conventional acquisition CBCT data reconstructed using standard 4DFDK.

Accuracy of a local positioning system for time-series speed and acceleration and performance indicators in game sports

ABSTRACT The objective was to determine the reliability and validity of a local positioning system (LPS) promising high accuracy at reduced product costs. Fifty-five random static positions in a gym (54.8 × 26.0 m) were obtained 10 times via LPS (50 Hz) and measuring tape. An athlete’s LPS-derived peak and time-series speed and acceleration during dynamic movements (n = 80) were compared with Vicon (100 Hz). Reliability and validity were assessed via Intraclass and Concordance Correlation Coefficients (ICC/CCC), root mean square errors, Bland-Altman plots, and analysis of variance. ICC3,1 (≥0.999) and CCC (0.387–0.999) were calculated for static positions (errors <0.22 m). CCC for time-series speed and acceleration, and peak speed, acceleration, and deceleration were 0.884–0.902, 0.777–0.854, 0.923, 0.486, and 0.731, respectively. Errors were larger in time-series acceleration (14.37 ± 3.77%) than in speed (11.99 ± 5.78%) ( = 0.472, p < 0.001) and in peak acceleration (28.04 ± 14.34%) and deceleration (25.07 ± 14.90%) than in speed (7.34 ± 6.07%) ( = 0.091, p < 0.01). LPS achieved excellent reliability and moderate-to-excellent validity of time-series speed and acceleration. The system accurately measured peak speed but not peak acceleration and deceleration. The system is suitable for analyses based on instantaneous speed and acceleration in game sports (e.g., energy estimations).

Development of a compact linear accelerator to generate ultrahigh dose rate high-energy X-rays for FLASH radiotherapy applications.

In recent years, the FLASH effect, in which ultrahigh dose rate (UHDR) radiotherapy (RT) can significantly reduce toxicity to normal tissue while maintaining antitumor efficacy, has been verified in many studies and even applied in human clinical cases. This work evaluates whether a room-temperature radio-frequency (RF) linear accelerator (linac) system can produce UHDR high-energy X-rays exceeding a dose rate of 40Gy/s at a clinical source-surface distance (SSD), exploring the possibility of a compact and economical clinical FLASH RT machine suitable for most hospital treatmentrooms. A 1.65m long S-band backward-traveling-wave (BTW) electron linac was developed to generate high-current electron beams, supplied by a commercial klystron-based power source. A tungsten-copper electron-to-photon conversion target for UHDR X-rays was designed and optimized with Monte Carlo (MC) simulations using Geant4 and thermal finite element analysis (FEA) simulations using ANSYS. EBT3 and EBT-XD radiochromic films, which were calibrated with a clinical machine Varian VitalBeam, were used for absolute dose measurements. A PTW ionization chamber detector was used to measure the relative total dose and a plane-parallel ionization chamber detector was used to measure the relative normalized dose of each pulse. The BTW linac generated 300-mA-pulse-current 11 MeV electron beams with 29kW mean beam power, and the conversion target could sustain this high beam power within a maximum irradiation duration of 0.75 s. The mean energy of the produced X-rays was 1.66 MeV in the MC simulation. The measured flat-filter-free (FFF) maximum mean dose rate of the room-temperature linac exceeded 80Gy/s at an SSD of 50cm and 45Gy/s at an SSD of 67.9cm, both at a 2.1cm depth of the water phantom. The FFF radiation fields at 50cm and 67.9cm SSD at a 2.1cm depth of the water phantom showed Gaussian-like distributions with 14.3 and 20cm full-width at half-maximum (FWHM) values, respectively. This work demonstrated the feasibility of UHDR X-rays produced by a room-temperature RF linac, and explored the further optimization of system stability. It shows that a simple and compact UHDR X-ray solution can be facilitated for both FLASH-RT scientific research and clinical applications.

Accelerator based epithermal neutron source for clinical boron neutron capture therapy

The world’s first accelerator based epithermal neutron source for clinical boron neutron capture therapy (BNCT) was designed, developed, and commissioned between 2008 and 2010 by Sumitomo Heavy Industries in collaboration with Kyoto University at the Kyoto University Institute for Integrated Radiation and Nuclear Science. The accelerator system is cyclotron-based and accelerates a proton up to an energy of approximately 30 MeV. The proton strikes a beryllium target, which produces fast neutrons that traverse a beam shaping assembly composed of a combination of lead, iron, aluminum, and calcium fluoride to reduce the neutron energy down to the epithermal range (∼10 keV) suitable for BNCT. The system is designed to produce an epithermal neutron flux of up to 1.4 × 10 9 n · cm − 2 · s − 1 (exiting from the moderator of a 12 cm diameter collimator) with a proton current of 1 mA. In 2017, the same type of accelerator was installed at the Kansai BNCT Medical Center and in March 2020 the system received medical device approval in Japan (Sumitomo Heavy Industries, NeuCure® BNCT system). Soon after, BNCT for unresectable, locally advanced, and recurrent carcinoma of the head and neck region was approved by the Japanese government for reimbursement covered by the national health insurance system.

Development and validation of analysis code for spallation products behavior in LBE coolant system of ADS comparing with the distribution data in MEGAPIE spallation target

It is important to evaluate the inventories and the release and transport behavior of the spallation products (SPs) including polonium-210 in the Lead-Bismuth Eutectic (LBE) coolant system of Accelerator Driven System (ADS) for the safety studies of the radiological hazard both in the cases of normal operation and accident. Especially, the transport and deposition inside the coolant circulation system and the evaporation from the coolant to the cover gas are dominant mechanisms to evaluate the release and transport behavior of SPs. University of Fukui and Japan Atomic Energy Agency (JAEA) have been developing the computer analysis code TRAIL (Transport of RAdionuclides In Liquid metal systems) which predicts the time dependent behavior of SPs within the LBE coolant system of ADS for the wide range of operational events. The TRAIL code is intended to deal with the SPs transport, deposition and evaporation behavior mechanistically in consideration of a variety of the physicochemical configuration of SPs in LBE. The physicochemical configuration of the SPs is essential to evaluate the release and transport behavior because the physical and chemical properties such as the molecular weight, the density, the solubility in LBE and the vapor pressure depend on the configuration. The SPs behavior modelled in the code are based on the generalized flow network model including pipe and tank components. The flow network model is constituted from mass and energy conservation equations in consideration of the mass and energy transfer due to coolant flow effect, deposition or adsorption of SPs onto the structure surfaces, transport into the cover gas due to evaporation and radioactive decay of the radioactive SPs. The source term of both radioactive and stable SPs in the LBE coolant is given as input and the radioactive decay chain model for the radioactive SPs is implemented in the code to evaluate the effect of precursors on the SPs mobility. This paper presents the recent advancement status of the code development and the validation results comparing with the distribution data of volatile SPs in MEGAPIE spallation target.

Construction and tests of phosphor view screen station for monitoring transverse profile of electron beam at PCELL

Development of an accelerator-based light source for generating coherent terahertz (THz) and mid-infrared (MIR) free-electron laser (FEL) is ongoing at the PBP-CMU Electron Linac Laboratory (PCELL). For producing high quality radiation, suitable electron beam property is necessary. In particle accelerator technology, transverse beam distribution and profile can be measured by using several techniques. The beam monitoring using view screen station is one of popular and effective methods. At PCELL, we use stations consisting of phosphor screen equipped with CCD camera to monitor, measure and record the beam image along the accelerator system and beamlines. The phosphor screen was chosen due to its high spatial resolution. The phosphor film is uniformly coated on a thin aluminium plate. Its green emission when electrons hitting the screen is matched well with the respond of the CCD camera. The screen can be moved in and out from the vacuum chamber using the air pressurized linear actuator. This paper presents about design, construction and tests of the screen stations at PCELL. The resolution of measurements for beam transverse profile and emittance is also be discussed.

Status of the engineering design of the IFMIF-DONES high energy beam transport line and beam dump system

IFMIF-DONES plant [1] (International Fusion Materials Irradiation Facility – DEMO Oriented Neutron Source) is currently being developed under the framework of a work package of the EUROfusion Consortium. It will be a facility located at the south of Spain in Granada. Its objective and main goal is the testing and qualification of fusion materials by the generation of a neutron flux with a broad energy distribution covering the typical neutron spectrum of a (D-T) fusion reactor. This is achieved by the Li (d,xn) nuclear reactions occurring in a liquid lithium target where a 40 MeV at 125 mA deuteron beam with a variable beam footprint between 200 mm × 50 mm and 100 mm × 50mm collides. The Accelerator Systems is in charge of providing such high energy deuterons to produce the required neutron flux. The High Energy Beam Transport line (HEBT) is the last subsystem of the IFMIF-DONES accelerator, and its main functions are to guide the deuteron beam towards the liquid lithium target and to shape it with the required rectangular reference beam footprints. The HEBT system includes a Beam Dump devoted to stop the beam during commissioning and start-up phases. The present work details the present status of the HEBT engineering design, including beam dynamics, vacuum configuration, radioprotection, beam diagnostics devices and remote handling analyses performed detailing the layout and integration of required components through-out the beamline.