B. Santos

High performance detectors for upgraded gamma ray diagnostics for JET DT campaigns

In forthcoming deuterium-tritium (DT) experiments on JET a significant population of alpha-particles will be produced. For operating alpha-particle diagnostics at high DT neutron fluxes, specific improvements have to be made. Proposed new detectors for gamma-ray measurements will be based on CeBr3 and LaBr3:Ce scintillators. They are characterized by a good energy resolution, a relatively high detection efficiency for a few MeV gamma-rays and a fast response time. An overview of scintillator parameters is presented. A description of the properties of photodetectors is given to indicate optimal setups. Results of measurements, using gamma-ray sources with energies up to a few MeV, are discussed with relation to the DT campaign requirements.

Retinal Neurodegeneration in Diabetic Patients Without Diabetic Retinopathy

Purpose To compare the thickness of all retinal layers between a nondiabetic group and diabetic patients without diabetic retinopathy (DR). Methods Cross-sectional study, in which all subjects underwent an ophthalmic examination including optical coherence tomography. After automatic retinal segmentation, each retinal layer thickness (eight separate layers and overall thickness) was calculated in all nine Early Treatment Diabetic Retinopathy Study (ETDRS) areas. The choroidal thickness (CT) also was measured at five locations. Generalized additive regression models were used to analyze the data. Results A total of 175 patients were recruited, 50 nondiabetic subjects and 125 diabetic patients without DR, stratified into three groups according to diabetes duration: group I (<5 years, n = 55), group II (5-10 years, n = 39), and group III (>10 years, n = 31). Overall, groups I and III of diabetic patients had a decrease in the photoreceptor layer (PR) thickness, when compared with the nondiabetic subjects in six ETDRS areas (P < 0.0007). Patients with more recent diagnosis (group I) had thinner PR than those with moderate duration (group II). Interestingly, patients with longer known disease (group III) had the thinnest PR values. There were no overall differences in the remaining retinal parameters. Conclusions Retinal thickness profile is not linear throughout disease duration. Even in the absence of funduscopic disease, PR layer in diabetic patients seems to differ from nondiabetic subjects, thus suggesting that some form of neurodegeneration may take place before clinical signs of vascular problems arise.

The upgraded JET gamma-ray cameras based on high resolution/high count rate compact spectrometers

The JET gamma-ray cameras have been recently upgraded within the gamma-ray camera upgrade project in support of development of JET high performance deuterium plasma scenarios and in preparation of deuterium-tritium experiments. New, dedicated detectors based on a LaBr3 crystal and silicon photo-multipliers have been developed and replaced pre-existing CsI detectors in all 19 channels. The new instrument gives opportunity of making two-dimensional gamma-ray measurements with a counting rate capability exceeding 1 MCounts/s (MCps) and energy resolution better than 5% at 1.1 MeV. The upgrade is of relevance for fast ion and runaway electron physics studies in high performance deuterium discharges and also in plasmas with tritium at neutron yields in the range up to about 5 × 1017 n/s.

Choroidal thinning: Alzheimer's disease and aging

The purpose of this study was to measure and to compare macular choroidal thickness (CT) between patients with mild Alzheimers disease (AD), patients without AD, and elderly patients.

TCV Advanced Plasma Control System Software Architecture and Preliminary Results

A new advanced plasma control system for the TCV Tokamak has been implemented based on an in-house developed high performance DSPs-based VME system, specially designed for real-time plasma control and event detection on fusion experiments. This paper describes the software architecture of the digital system as well as the integration of the physicists control algorithms in the DSPs software. The integration conditions on the TCV control system and the first results of the real-time control operation are also presented. Finally, a critical analysis of the system performance and the experimental operation of TCV APCS is discussed.

ITER prototype fast plant system controller based on ATCA platform

The ITER Fast Plant System Controllers (FPSC) are based on embedded technologies and will be devoted to both data acquisition tasks (sampling rates >1 kSPS) and control purposes in closed-control loops whose cycle times are below 1 ms. Fast Controllers will be dedicated industrial controllers with the ability to: i) supervise other fast and/or slow controllers; ii) interface to actuators and sensors and high performance networks. This contribution presents an FPSC prototype, specialized for data acquisition, based on the ATCA (Advanced Telecommunications Computing Architecture) standard. This prototyping activity contributes to the ITER Plant Control Design Handbook (PCDH) effort of standardization, specifically regarding fast controller characteristics. For the prototype, IPFN is developing a new family of ATCA modules targeting ITER requirements. The modules comprise an AMC carrier/data hub/timing hub compliant with the upcoming ATCA extensions for Physics and a multi-channel with galvanic isolation hot-swappable digitizer designed for serviceability. The design and test of a peer-to-peer communications layer for the implementation of a reflective memory over PCI Express and the design and test of an IEEE-1588 transport layer over a high performance serial link was also performed. In this work, a complete description of the solution is presented as well as the integration of the controller into the standard CODAC environment. The most relevant results of real tests will be addressed, focusing in the benefits and limitations of the applied technologies.

Test results of an ITER relevant FPGA when irradiated with neutrons

The data acquisition and control instrumentation in port cell cubicles of tokamak ITER will be irradiated with neutrons, during the fusion reactor operation. A Virtex-6 FPGA from Xilinx (XC6VLX365T-1FFG1156C) is used on the ATCA-IO-PROCESSOR board, included in the ITER Catalog of I&C products - Fast Controllers. The Virtex-6 is a re-programmable logic device where the configuration is stored in Static RAM (SRAM), functional data stored in dedicated Block RAM (BRAM) and functional state logic in Flip-Flops. Single Event Upsets (SEU) due to the ionizing radiation of neutrons causes soft errors, unintended changes (bit-flips) to the values stored in state elements of the FPGA. The SEU monitoring and soft errors repairing, when possible, were explored in this work. An FPGA built-in Soft Error Mitigation (SEM) controller detects and corrects soft errors in the FPGA configuration memory. SEU sensors with Error Correction Code (ECC) detect and repair the BRAM memories. Proper management of SEU can increase reliability and availability of control instrumentation hardware for nuclear applications. The results of the tests performed using the SEM controller and the BRAM SEU sensors are presented for a Virtex-6 FPGA (XC6VLX240T-1FFG1156C) when irradiated with neutrons from the Portuguese Research Reactor (RPI), a 1 MW nuclear fission reactor operated by IST in the neighborhood of Lisbon. Results show that the proposed SEU mitigation technique is able to repair the majority of the detected SEU errors in the configuration and BRAM memories.

Integration of EPICS subsystem control on FireSignal

This paper presents a slow control system based on Experimental Physics and Industrial Control System (EPICS) and FireSignal technology for fusion devices, that is being developed for ISTTOK and COMPASS tokamaks. In this approach, the machine sub-systems control is based in micro-controllers. These sub-systems can handle automatically the necessary procedures before, during and after a plasma discharge, including safety protocols. An EPICS based supervisory control software then integrates all machine subsystems for central monitoring, configuration, logging and alarm management. Instead of the usual EPICS MEDM client tools, remote monitoring and configuration is accomplished by means of a specifically developed Java application using the CAJ library for EPICS and Common Object Request Broker Architecture (CORBA). This application behaves also as FireSignal Client, allowing the subsystems to be completely integrated on a FireSignal-based CODAC with all Process Variables (PV) and relevant control events being recorded in the central database. Through the FireSignal operator console, the so called FS User Client, it is possible to present a dedicated GUI for each subsystem, thus providing the machine operator a complete overview of the state of the machine and full control capabilities.

TCV Advanced Plasma Control System Software Architecture and Results

A new advanced plasma control system for the TCV tokamak has been implemented based on an in-house developed high performance DSPs-based VME system, specially designed for real-time plasma control and event detection on fusion experiments. This paper describes the software architecture of the digital system as well as the integration of the physicists control algorithms in the DSPs software. The integration conditions on the TCV control system and the first results of the real-time control operation are also presented. Finally, a critical analysis of the system performance and the experimental operation of TCV APCS is discussed.

Implementation of an ATCA/AXIe board for fast control and data acquisition systems of nuclear fusion devices

The implementation of an ATCA/AXIe board, developed for fast control and data acquisition systems of nuclear fusion devices, is presented. The implemented board was designed for systems requiring high levels of reliability and availability, such as those of long duration discharges or steady-state operation nuclear fusion experiments. Following ITER instrumentation guidelines for rear signals interfaces, the board comprises a passive rear transition module allowing analogue IO cabling connectivity and cable-less hop-swap maintenance of the front board. Onboard ADC modules have differential input, galvanic isolation and an ADC chopper circuit which assures offset compensation over time for integrators used on magnetic diagnostics. Classical clock and trigger synchronism as well as IEEE-1588/IRIG timing are supported. Full ATCA redundancy and management are also provided.