Engineering topics

Martin, V

Publications and source records attributed to Martin, V.

3 records

DOE OSTI2011

The ITER VIS/IR wide angle viewing system: Challenges and on-going R and D

The ITER tokamak is the next generation fusion device which will allow studying burning plasma obtained by a Deuterium-Tritium (D-T) fusion reaction during hundreds of seconds. ITER vacuum vessel real-time protection will be mandatory during plasma operation to avoid water leaks and critical plasma facing components degradation. The protection system will be based on a wide angle viewing system (WAVS) composed with 18 visible (VIS) and 18 infrared (IR) cameras covering 80 % of the vacuum vessel which will be one of the major imaging systems of ITER. Compared to protection systems routinely used on current tokamaks and based on imaging (VIS and/or IR), new constraints must be taken into account because of their influence on the system performance: the harsh environment (high neutron flux) and the metallic plasma facing components (both first wall and divertor). In this new demanding context, we have achieved three mandatory R and D studies starting from the understanding of the source of signals by using realistic photonic simulation up to real-time processing strategy taken into account first order optical design constraints to define what type of performance could be reached for ITER vacuum vessel protection. (authors)

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2010

Wall reflection issues for optical diagnostics in fusion devices

The problem of light reflection has been raised as a high priority issue for optical diagnostics in next step fusion devices where metallic wall environment will generate significant perturbations in the diagnostics measurements. Tore Supra is a large size tokamak equipped with water-cooled stainless-steel panels used to sustain the plasma long shot radiations. These panels are highly reflective and affect significantly optical systems. In particular, we show that the infrared imaging diagnostic, which surveys the plasma facing component surface temperature for safety purposes, can give incorrect information due to reflected light coming from the bottom limiter. In the visible range, motional Stark effect and Zeff measurements experience important drifts during the plasma heating phases due to parasitic light coming from the limiter, but also from the plasma itself when the viewing lines are facing the reflecting walls. In the next step fusion devices such as ITER, the possibility to use optical measurements needs to be accessed by a modeling of the diagnostic light in its machine environment and the development of new techniques of online correction.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2010

New field programmable gate array-based image-oriented acquisition and real-time processing applied to plasma facing component thermal monitoring

During operation of present fusion devices, the plasma facing components (PFCs) are exposed to high heat fluxes. Understanding and preventing overheating of these components during long pulse discharges is a crucial safety issue for future devices like ITER. Infrared digital cameras interfaced with complex optical systems have become a routine diagnostic to measure surface temperatures in many magnetic fusion devices. Due to the complexity of the observed scenes and the large amount of data produced, the use of high computational performance hardware for real-time image processing is then mandatory to avoid PFC damages. At Tore Supra, we have recently made a major upgrade of our real-time infrared image acquisition and processing board by the use of a new field programmable gate array (FPGA) optimized for image processing. This paper describes the new possibilities offered by this board in terms of image calibration and image interpretation (abnormal thermal events detection) compared to the previous system.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗