Upgrades of Diagnostic Techniques and Technologies for JET next D-T Campaigns

Conference · Wed Jul 01 00:00:00 EDT 2015

DOI:https://doi.org/10.1109/TNS.2016.2527243· OSTI ID:22531215

Murari, Andrea ^[1]

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1. Consorzio RFX - CNR, ENEA, INFN, Universita di Padova, Acciaierie Venete SpA,Corso Stati Uniti 4, 35127 Padova (Italy)

JET next D-T campaign is presently scheduled for the year 2017. The main scientific objectives include the assessment of the isotopic effects on various plasma aspects: mainly on confinement, on the threshold to access the H mode and on ELM behaviour. From a technical point of view, the total yield of the entire D-T phase is expected to be 1.7 1021 neutrons, about a factor of six higher than the previous main D-T campaign on JET, DTE1. Therefore the radiation field will be quite relevant for next step devices, since the neutron flux at the first wall (∼10{sup 16} n/cm{sup 2}s), for example, will be comparable to the one in ITER behind the blanket. From a point of view of diagnostics developments, for many years JET diagnostics have been upgraded in order to provide adequate support for the scientific exploitation of a D-T campaign. The main efforts have concentrated on improving three main aspects of JET measuring capability: 1) the quality of the measurements of the electron and ion fluids to support the plasma physics programme 2) the diagnostic for the fusion products 3) diagnostic technologies for ITER. In terms of general diagnostic capability, compared to the previous DTE1, JET diagnostics have a much better spatial and temporal resolution of both the ion and electron fluid (about one order of magnitude improvement for each parameter). The consistency of the various independent measurements of the same parameters has also increased significantly; the three independent measurements of the electron temperature, for example, agree now within 5%. Moreover, solutions are being addressed to operate some cameras, both visible and IR, even during the full D-T phase to provide imaging of the plasma and the first wall. Various upgrades of neutral particle analysis are being considered, mainly to measure the isotopic composition. A new set of reflectometers is expected to provide valuable information about the changes in the turbulence with the different fuel mixtures. With regard to the fusion products, JET now can deploy a consistent set of techniques to measure the neutron yield and neutron spectra and to diagnose the fast particles. A full calibration of the neutron diagnostics with a 14 MeV source is being considered, after the recent very successful calibration for the 2.45 MeV neutrons. Vertical and horizontal lines of sight are foreseen for neutron and gamma spectrometry, in order to better determine the thermal neutron yield and to separate the trapped and passing components of the alphas. Various gamma ray spectrometers are being developed to cover all the various operational scenarios, from trace tritium to 50-50 D-T operation. The redistribution of the alphas will be measured with the gamma ray cameras, recently upgraded with full digital electronics; new detectors are being considered to bring the time resolution of the system in the ten of ms range. The lost alphas will also be diagnosed with improved spatial and temporal resolution, using Faraday cups and a scintillator probe. From a technological perspective, the D-T campaign will provide a unique opportunity to test ITER relevant technologies. From radiation hard detectors, for example Hall probes, to neutron absorbers and to shielding concepts, the potential of various solutions in a realistic 14 MeV radiation field will be assessed. The effects of neutrons and gamma on ancillary technologies and systems, such as fibre optics and electronics circuits, are also expected to be sufficiently high to derive useful information about the competitive advantage of various alternatives.

• Research Organization: Institute of Electrical and Electronics Engineers - IEEE, 3 Park Avenue, 17th Floor, New York, N.Y. 10016-5997 (United States)
• OSTI ID: 22531215
• Report Number(s): ANIMMA-2015-IO-158; TRN: US16V0377102156
• Resource Relation: Journal Volume: 63; Journal Issue: 3; Conference: ANIMMA 2015: 4. International Conference on Advancements in Nuclear Instrumentation Measurement Methods and their Applications, Lisboa (Portugal), 20-24 Apr 2015; Other Information: Country of input: France
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
D-T OPERATION
EDGE LOCALIZED MODES
ELECTRON TEMPERATURE
FARADAY CUPS
FIRST WALL
GAMMA CAMERAS
GAMMA SPECTROSCOPY
H-MODE PLASMA CONFINEMENT
ISOTOPE EFFECTS
ISOTOPE RATIO
ITER TOKAMAK
JET TOKAMAK
MEV RANGE
NEUTRAL PARTICLES
NEUTRON FLUX
NEUTRON SPECTRA
PLASMA
PLASMA DIAGNOSTICS
TRITIUM