Runaway electron measurements in the JET tokamak

Esposito, B.; Martin-Solís, J.R.; Belle, P. van; Jarvis, O.N.; Marcus, F.B.; Sadler, G.; Sánchez, Raúl; Fischer, Baruch; Froissard, P.; Adams, J. M.; Cecil, Ed; Watkins, N. W.

doi:10.1088/0741-3335/38/12/001

Cited by 58 publications

(52 citation statements)

References 20 publications

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“…It is important to remark that limited detection efficiencies are expected from gamma-ray profile monitor. The spectral lines resolution is affected by the tokamak geometry, uncertainty due to the nonlinear response of CsI(Tl) detectors, the absorber materials in each Line-Of-Sight (LOS), and low counting statistics [11,12].…”

Section: Resultsmentioning

confidence: 99%

Data pre-processing using an FPGA by binning gamma ray energies and forwarding consolidated spectra data

Fernandes

Pereira

Neto

et al. 2015

Fusion Engineering and Design

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h i g h l i g h t s• JET monitor equipped with a DAQ system to digitize gamma signals from 19 detectors.• DAQ FPGAs used for real-time processing and streaming the gamma-ray energy values.• New algorithm was designed to produce at FPGA real-time spectra from energy values.• Spectra built at FPGA ensures streamed packets not limited by count rate.• New algorithm is relevant for future experiments expecting high event count rates. a r t i c l e i n f o Gamma-ray diagnostics are considered of crucial importance for understanding the plasma behavior of next fusion devices. Among other physical phenomena, gamma-ray spectra can provide information about the fusion reactions rate and the fast ions temperature and confinement, indicators of how close we are from reaching self-sustained burning plasmas. Accordingly, dedicated gamma-ray diagnostics are currently installed at the Joint European Torus (JET). The 2D gamma-ray profile monitor is one of these diagnostics, equipped with an Advanced Telecommunications Computing Architecture (ATCA) Data Acquisition (DAQ) system, capable of digitizing gamma-ray signals from the 19 photodiode detectors. The DAQ system includes Field Programmable Gate Array (FPGA) devices, with embedded processing algorithms. These algorithms are responsible for processing the gamma-ray signals acquired from each detector in real-time, and for periodically streaming the corresponding energy values to the DAQ host. However, for higher count rates it will be unfeasible to stream periodically all the energy values without loss. Thus, a new algorithm was designed, capable to produce real-time spectra at FPGA from the processed energy values. The spectra should be periodically streamed, delivering binned data rather than a value for each gamma-ray. This allows to reduce the data rate, avoiding data losses. Consequently, the streaming data can be used for control purposes, as demanded by next fusion experiments with long plasma discharges of high energy/count rate content. This work describes the real-time spectrum code developed for FPGA along with the attained results. It was concluded that the spectrum code is suitable for implementation in any spectroscopy diagnostic, whenever real-time spectra are required.

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Section: Resultsmentioning

confidence: 99%

Data pre-processing using an FPGA by binning gamma ray energies and forwarding consolidated spectra data

Fernandes

Pereira

Neto

et al. 2015

Fusion Engineering and Design

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“…Myra and Catto [41] deduced an expression that related the runaway diffusion coefficient with the magnetic coefficient and in turn with the electron thermal conductivity. From a more general scenario, where the effect of electrostatic turbulence also is considered, an expression of the runaway diffusion coefficient is given as [18] The contribution of the magnetic turbulence alone is given as…”

Section: Estimates Of Magnetic Fluctuationmentioning

confidence: 99%

“…In more recent machines, with much better confinement properties, runaways were observed to be generated and confined more towards the core and have much reduced diffusion coefficients (e.g. JET: D RE ∼ 0.2 m 2 /s for r/a < 0.5 [18]; TEXTOR: D RE < 0.01 m 2 /s for 25 MeV [19]; Tore Supra: D RE = 0.1-0.2 m 2 /s in the range 100-200 keV [20]; FTU: ∼0.03 m 2 /s at current flat top [21]). Most of the parallel current densities at the edge of the reversed-field pinch devices were observed to be carried by the nonthermal electron distribution, and found to have significant effects on the edge physics [22] (for e.g., ZT-40M: superthermal electron energies W RE ∼ 0.6-6 keV and energy flux q || ∼ 140 MW/m 2 [23], TPE-1RM20: W RE ∼ 2-8 keV [24]; RFX: T ⊥ ∼ T ≈ 100-200 eV and energy flux q ⊥ ∼ 100 MW/m 2 [25]).…”

Section: Introductionmentioning

confidence: 99%

Comparative study of runaway electron diffusion in the rise phase of low q a and normal q a discharges in the SINP tokamak

Narayanan

Iyengar

2010

Pramana - J Phys

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The behaviour of runaway electrons in the SINP tokamak, which can be operated in a normal edge safety factor (qa) (NQ) discharge configuration as well as in a low q a (LQ) configuration, was experimentally investigated, during the initial plasma generation phase. An energy analysis of the runaway electron dynamics in the rise phase of the SINP tokamak discharges was also made. A comparison of the runaway electron diffusion coefficients in NQ and LQ is carried out in this paper.

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“…The energetic ions give rise to the intense -ray emission reacting with either fuel ions or main plasma low-Z impurities, that is, beryllium and carbon [4,5]. HXR and -ray intensities, as well as their energy spectra recorded with collimated spectrometers deliver essential data on energy distributions of fast electrons and energetic ions (fusion reaction products, ion-cyclotron resonance frequency (ICRF) -accelerated ions, NBI--injected ions).…”

Section: Introductionmentioning

confidence: 99%

Characterization of some modern scintillators recommended for use on large fusion facilities in γ-ray spectroscopy and tomographic measurements of γ-emission profiles

et al. 2017

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Abstract. LaBr 3 :Ce,CeBr 3 and GAGG:Ce scintillators were investigated and the determined characteristics were compared with those obtained for the well-known and widely used CsI:Tl and NaI:Tl crystals. All the detectors were of the same size of 10 × 10 × 5 mm 3 . The aim of this test study was to single out scintillation detectors most suitable for -ray spectrometry and -ray emission radial profi le measurements in high-temperature plasma experiments. Decay time, energy resolution, non-proportionality and full energy peak detection effi ciency were measured for -ray energies up to 1770 keV. Due to their good energy resolution, short decay time and high detection effi ciency for MeV gamma rays, LaBr 3 :Ce and CeBr 3 scintillators are proposed as the best candidates for use especially under conditions of high count rates, which are expected in the forthcoming DT experiments.

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Runaway electron measurements in the JET tokamak

Cited by 58 publications

References 20 publications

Data pre-processing using an FPGA by binning gamma ray energies and forwarding consolidated spectra data

Data pre-processing using an FPGA by binning gamma ray energies and forwarding consolidated spectra data

Comparative study of runaway electron diffusion in the rise phase of low q a and normal q a discharges in the SINP tokamak

Characterization of some modern scintillators recommended for use on large fusion facilities in γ-ray spectroscopy and tomographic measurements of γ-emission profiles

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