Using low voltage ionization chamber (LVIC) in current mode for energy spectrum reconstruction: Experiments and validation

Due to the International Thermonuclear Experimental Reactor (ITER) radiative environment, in particular during high D-T power phase, classic x-ray detectors, such as semiconductor diodes, might be too fragile and are thus not viable. Instead, robust detectors, such as gas-filled detectors, are nowadays considered. The Low Voltage Ionization Chamber (LVIC) is one of the most promising candidates for x-ray measurement during the ITER nuclear phase. A complete model of the detector, recently developed at IRFM (Intitute for Research on Magnetic Fusion), now requires experimental validation. Experimental testing at the IRFM laboratory of an ITER industrial LVIC prototype and comparison with modeling are presented. In particular, an original approach to extract information on the x-ray spectrum from current-mode LVIC measurement is validated experimentally.

Multichannel gas electron multiplier based soft x-ray field-programmable gate array measurement system for W-Environment in Steady-state Tokamak (WEST): Hardware, installation, and first plasma acquisition

The work describes a novel approach to the design of a fast, multichannel measurement system for plasma diagnostics [A. Wojenski et al., Fusion Eng. Des. 123, 727 (2016)]. Its main scope is to provide measurements of soft X-ray (SXR) emission during plasma phenomena at the W-Environment in Steady-state Tokamak (WEST), especially for monitoring and tracing tungsten impurities. This paper describes the vertical Gas Electron Multiplier (GEM) camera installed at the WEST [M. Chernyshova et al., J. Instrument. 10, P10022 (2015)]. The designed GEM detector readout board has more than 100 channels, resulting in high-performance requirements for the data acquisition and processing system. The novel system construction approach is that the unit works on the raw signals providing a high quality of the data, especially in the scope of pileup effect analysis. In the case of doubtful results, the source data can be easily reviewed offline. The data selection and transmission are done in Field-Programmable Gate Arrays (FPGAs) on the custom boards with the custom Peripheral Component Interconnect (PCI)-Express Gen2 switch that allows us to register signals from multiple FPGAs and then process the data by complex algorithms [G. Kasprowicz et al., J. Fusion Energy 38, 480 (2019)]. The firmware is replaceable and different working modes can be applied (some under verification): global trigger mode, high-speed data serialization, and extended signal registration. Low level optimized central processing unit software for data readout was also designed [P. Linczuk et al., J. Instrum. 14, C05001 (2019)]. The installation of the system is described due to complex system components' distribution. The first results of the successful acquisition of the plasma at the WEST are discussed. The corresponding SXR energy and topology spectra were computed. Those are the first technical measurements of the system to ensure verification of data quality.

Data Quality Monitoring Considerations for Implementation in High Performance Raw Signal Processing Real-time Systems with Use in Tokamak Facilities

Data quality of the tokamaks diagnostics is often a neglected topic. In literature it is rather rare to find considerations regarding the data quality received from the diagnostic systems’ sensors. The scope of the paper is to provide a discussion regarding systems’ construction and analysis in scope of implementation of data quality monitoring methods for a new generation of diagnostics. Mainly considerations are performed regarding the necessity of DQM (Data Quality Monitoring) implementation, functionality, performance and required system resources. The covered topics are related to basics of system construction including: system layout and construction blocks, data processing stages, signal processing modes, system construction with resource estimation in scope of DQM implementation. Based on the covered points, it is possible to plan the extra resources or specific construction, to provide reliable design with data quality monitoring features. The data quality monitoring aspect is especially important in the modern diagnostics working with a real-time feedback loop. Such approach could be especially interesting for the ITER-like projects, since the quality of the data may directly influence the behavior of the control systems during plasma phenomena. The work is based on experience in design work of various high performance diagnostic systems for plasma physics and high energy physics.

174 Use of mesenchymal stem cell treatment to improve oocyte yield and invitro embryo production in cattle

Cumulative tissue damage and chronic inflammation associated with frequent ovum pickup (OPU) may lead to a progressive reduction in the number and quality of the oocytes recovered, particularly in donors with a high antral follicle count. The aim of this study was to evaluate the effect of an intraovarian treatment with mesenchymal stem cells (MSC) on oocyte yield, quality, and development potential during invitro embryo production (IVEP) in cattle donors undergoing repeated OPU. Mesenchymal stem cells were previously isolated from adipose tissue, cultured in Dulbecco's modified Eagle medium until reaching 80% confluence, isolated with trypsin, and frozen in liquid N2 until use. Characterisation of MSC was carried out according to the guidelines of the International Society for Cellular Therapy. Nelore (Bos indicus) cows (n=5) were used in this study, with the ovaries as replicates. The cows underwent eight OPU sessions at 15-day intervals, and the oocytes recovered were graded and used for IVEP with the semen of a single sire and batch under similar invitro culture conditions. To ensure a high inflammatory response, immediately after the fourth OPU session all ovaries received 30 additional punctures, performed with a 16-gauge Jelco needle. Six hours later, the left ovary of each cow was injected with 500µL of Dulbecco's modified phosphate buffered saline (control ovary) and the right ovary received 500µL of Dulbecco's modified phosphate buffered saline with 2.5×106 allogenic MSC (treated ovary). Oocyte yield and embryo production before and after treatment were recorded for each ovary and donor. Grade I blastocysts produced from control and treated ovaries were used for gene expression evaluation. Data was analysed using the repeated-measures procedure of SAS (SAS Institute Inc.) to account for the effects of treatment, time, and interactions. There was no difference (P>0.05) in any endpoint before treatment (sessions 1-4) between the right and left ovaries. Thus, differences between ovaries observed in OPU sessions 5-8 were assumed to be due to the treatment. After the injection of MSC, more total and viable oocytes were collected from the right ovaries compared with the left ovaries (15.3±2.2 vs. 8.7±1.2 (P<0.02) and 13.6±2.1 vs. 7.1±1.0 (P<0.01), respectively), resulting in more embryos produced invitro (7.6±1.2 vs. 3.6±0.6, respectively; P<0.01) as well as more initial and expanded blastocysts (1.4±0.3 vs. 0.4±0.1 and 4.4±0.9 vs. 2.1±0.4, respectively; P<0.04). The proportion of viable oocytes recovered from the right ovary after treatment was greater than that from the left ovary (89.1% vs. 81.5%; P<0.05). However, blastocyst rates did not differ between ovaries before or after treatment (50.4% vs. 55.5%: P>0.05). In the blastocysts produced from treated ovaries, SLC2A3 was overexpressed (P<0.04), whereas there was no difference for the expression of KRT8, PLAC8, SLC2A1, CASP3, PRDX3, or SOD2 (P>0.05), suggesting potential differences in glucose uptake and metabolism. In conclusion, intraovarian treatment with MSC improved oocyte yield and quality and may be an alternative to increase IVEP from donors under intensive OPU schedules. This research was supported by CNPq, CAPES, and Fazenda Grupo Esplanada.

Probiotics maintain intestinal secretory immunoglobulin A levels in healthy formula-fed infants: a randomised, double-blind, placebo-controlled study

Formula-fed infants are more susceptible to infectious diseases because they lack the maternal immune factors transferred from breast milk, while their own immune system is still immature. As timely probiotic administration was suggested to promote immune system development in formula-fed infants, this study aimed at assessing the safety and the effects of a probiotic supplement (Bifidobacterium infantis R0033, Bifidobacterium bifidum R0071, and Lactobacillus helveticus R0052) on mucosal immune competence and digestive function in formula-fed infants. Healthy infants (3.5-6 months old) were randomised to receive either probiotic- (n=66) or placebo-supplemented (n=66) formula once a day for four weeks. In the probiotics group, faecal secretory immunoglobulin A (SIgA) levels remained similar between visit 2 (baseline; V2) and visit 3 (end-of-treatment; V3), but decreased in the placebo group. Changes in SIgA levels following treatment (log₁₀ΔV3-V2 [95%CI]) between the probiotic and placebo groups were statistically significant (23 ng/dl [-57;102] and -137 ng/dl [-212;-62], respectively (P=0.0044; ANCOVA)). While log₁₀ΔV3-V2 [95%CI] for salivary SIgA levels increased in both groups, this trend was more pronounced in the probiotics than in the placebo group with an increase of 123 ng/dl [9;236] and 37 ng/dL [-72;147], respectively (P=0.2829; ANCOVA). The weekly average number of stools/day was significantly higher in the probiotics group compared to placebo during the last week of treatment for the per protocol population. There was no difference in microbiota composition or anthropometric parameters between groups. No serious adverse event was reported, and all adverse events were mild and unrelated to the product or study. Our results show that formula-fed infants receiving probiotics maintained higher faecal SIgA levels at the end of the four-week treatment period, suggesting a positive effect of probiotics on SIgA production. This study demonstrates the safety of this probiotic formulation in infants. Formula-fed infants may benefit from probiotics supplementation to sustain the development of mucosal immunity.

The new magnetic diagnostics in the WEST tokamak

The WEST tokamak consists of a major upgrade of the superconducting medium size tokamak Tore Supra aiming at testing ITER divertor components. Such modification has required rebuilding a full set of magnetic diagnostics. The project was started in 2013 and completed in 2016. The diagnostic consists of a set of 469 sensors (421 pick-up coils, 36 flux loops, and 12 Rogowski coils) installed in the WEST vacuum vessel. New analog integrators have been developed in order to obtain the magnetic field and flux from the raw signal of the sensors. During the startup phase of WEST, plasma currents of the order of a few kilo amperes were measured despite much larger current of the order of hundreds of kilo amperes flowing in nearby conducting structures. The diagnostic is now fully operational and exhibits a noise level of about 0.5 mT on the magnetic field, and 2.0 mWb on flux loops allowing identifying the plasma boundary with an accuracy of a few millimeters on a 2 ms time cycle.

Soft x-ray tomography for real-time applications: present status at Tore Supra and possible future developments

This paper is focused on the soft x-ray (SXR) tomography system setup at Tore Supra (DTOMOX) and the recent developments made to automatically get precise information about plasma features from inverted data. The first part describes the main aspects of the tomographic inversion optimization process. Several observations are made using this new tool and a set of shape factors is defined to help characterizing the emissivity field in a real-time perspective. The second part presents a detailed off-line analysis comparing the positions of the magnetic axis obtained from a magnetic equilibrium solver, and the maximum of the reconstructed emissivity field for ohmic and heated pulses. A systematic discrepancy of about 5 cm is found in both cases and it is shown that this discrepancy increases during sawtooth crashes. Finally, evidence of radially localized tungsten accumulation with an in-out asymmetry during a lower hybrid current drive pulse is provided to illustrate the DTOMOX capabilities for a precise observation of local phenomena.

Characterization of a 2D soft x-ray tomography camera with discrimination in energy bands

A gas detector with a 2D pixel readout is proposed for a future soft x-ray (SXR) tomography with discrimination in energy bands separately per pixel. The detector has three gas electron multiplier foils for the electron amplification and it offers the advantage, compared with the single stage, to be less sensitive to neutrons and gammas. The energy resolution and the detection efficiency of the detector have been accurately studied in the laboratory with continuous SXR spectra produced by an electronic tube and line emissions produced by fluorescence (K, Fe, and Mo) in the range of 3-17 keV. The front-end electronics, working in photon counting mode with a selectable threshold for pulse discrimination, is optimized for high rates. The distribution of the pulse amplitude has been indirectly derived by means of scans of the threshold. Scans in detector gain have also been performed to assess the capability of selecting different energy ranges.

An original calibration technique for soft x-ray detectors and its use in the Tore Supra tomographic system

This paper describes in detail the recent progresses which have been made in Tore Supra for developing a new technique of calibration of the soft x-ray (SXR) detectors in the range 1-30 keV. The diode response as a function of the flux of photons resulted accurately linear over almost three orders of magnitude. Apart from a limited number of deficient detectors, promptly replaced with new ones, the spread of the diode responses (84 detectors) is about 20% total of the average value. It allowed the derivation of the calibration factor for each detector of the tomography system. The effect of the environmental temperature, in the range 15 degrees-40 degrees, has also been studied, revealing that up to 35 degrees the linearity of diode response and these calibration factors remain constant. It demonstrates the capability of discriminating slight and localized changes in the two dimensional spatial distribution of the SXR intensity.

Characterization of detection efficiency as function of energy for soft x-ray detectors

A new technique has been especially developed for determining the detection efficiency of the silicon surface barrier diodes used for tomography reconstructions at Tore Supra, as function of the energy of the x-ray photons, in the range of 4-25 keV. The response of these diodes has been studied for different bias voltages (0-120 V), with a portable x-ray electronic tube and a cooled Si-p-i-n diode, working in photon counting mode, for the absolute calibration.