CVD diamond photodetectors for FTU plasma diagnostics

Cesaroni, S; Angelone, M.; Apruzzese, G.; Bombarda, F.; Gabellieri, L.; Marinelli, M.; Palomba, S.; Pucella, G.; Романо, А.; Verona, C.; Centioli, C.; Grosso, Andrea; Piergotti, V.; Rocchi, G.; Sibio, A.; Tilia, B.

doi:10.1016/j.fusengdes.2021.112323

Cited by 11 publications

(6 citation statements)

References 10 publications

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“…In figure 2 are reported the equilibrium profiles obtained for Hydrogen and Helium, where we considered respectively a pinch To evaluate our estimates, a comparison is made with the experimental data as reported in table 1. In Proto-sphera, temperature measurements are obtained for Helium only with a spectroscopic technique [9] and radiation power measurements are made with a diamond detector sensitive to the UV radiation [10]. Our estimations for the mean electronic temperature and radiated power are in a good agreement with measurements.…”

Section: Results and Conclusionsupporting

confidence: 55%

A new indirect measurement method of the electron temperature for the Proto-sphera's pinch plasma

Napoli

Alladio

et al. 2023

J. Inst.

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This article presents a new method for estimating the electron temperature of the Proto-sphera's screw pinch. The temperature radial profile is obtained by a self-consistent modeling of a 1D MHD equilibrium along with a 0D power balance of the plasma column, given measurements and estimates of the axial pinch plasma current, of the plasma rotational frequency and, at the equatorial plane, of the electron density radial profile, of the edge poloidal magnetic field, of the edge electron temperature and of the neutrals pressure in the vacuum vessel. The plasma is considered in equilibrium with its neutral phase and in constant rotation. A MATLAB code has been developed with the aim of estimating the MHD radial equilibrium profiles, the thermodynamic plasma state and the neutrals profile. The numerical estimates are compared with available experimental data showing a good agreement.

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Section: Results and Conclusionsupporting

confidence: 55%

A new indirect measurement method of the electron temperature for the Proto-sphera's pinch plasma

Napoli

Alladio

et al. 2023

J. Inst.

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“…Beautiful examples of plasma fast events have been recorded in the course of the two last experimental campaigns in 2019 of the high field FTU tokamak (R 0 = 0.9 m, a = 0.3 m, B T < 8 T, I p < 1.6 MA) [9] for several different plasma conditions, confirming the fast response capabilities of diamond detectors [10], and showing a much wider range of potential diagnostic utilizations. The main results are presented in the following, each pointing to possible applications with more specifically designed and appropriate mounting of single crystal CVD diamond detectors than available for these scoping experiments.…”

Section: Experimental Results From Ftumentioning

confidence: 58%

CVD diamond detectors for fast VUV and SX-ray diagnostics on FTU

Bombarda¹,

Angelone²,

Apruzzese³

et al. 2021

Nucl. Fusion

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The diagnostic performances of photodetectors based on Chemical Vapor Deposition (CVD) single crystal diamonds that were installed on one of the equatorial ports of the FTU tokamak during the last six months of operation of the machine are reported. Examples of plasma fast events have been collected in several different plasma conditions, confirming the fast response capabilities of diamond detectors and the high S/N ratio. During the runaway control and mitigation experiments, for example, the so-called Anomalous DopplerInstabilities were observed as sharp peaks of Ly-α emission caused by fast electrons hitting the wall, as a result of RE beam instabilities, perfectly correlated in time with other magnetic diagnostics and fast EC polychromator signals. Fast oscillations in the plasma emission are also observed in the presence of tearing modes, while other interesting observations relate to pellet ablation processes. The CVD diamond detectors were installed on FTU in view of their possible use for replacement of the Si photodiodes currently adopted for Soft X-ray tomography on future devices with harsher radiation environments. In fact, it was realized that the relatively flat response of the UV diamond sensor opened the possibility of using these detectors as bolometers. The first encouraging results have prompted launching an R&D program for the development of full-fledged diamond bolometers, which will be especially well suited for the coverage of the divertor and edge regions in high performance devices, in the energy range from 10 eV to about 20 keV.

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“…In such a harsh environment, most of the diagnostics used in present reactors will not be able to operate; therefore, alternatives must be found. Diamond-based detectors are one possibility, both because of their endurance to high neutron fluxes and their broadband responsivity [30,31]. Since 2007, two diamond detectors for VUV and Soft X-ray measurements have been installed at JET [30] to investigate their potentialities, and more recently on the FTU machine [31,32].…”

Section: Diagnosticsmentioning

confidence: 99%

“…Diamond-based detectors are one possibility, both because of their endurance to high neutron fluxes and their broadband responsivity [30,31]. Since 2007, two diamond detectors for VUV and Soft X-ray measurements have been installed at JET [30] to investigate their potentialities, and more recently on the FTU machine [31,32]. This is the reason why in the following, data collected by the UV diamond detector are shown for the first time in comparison with data from the spectroscopic cameras at JET measuring the ELM fingerprints in Be II emission line.…”

Section: Diagnosticsmentioning

confidence: 99%

An Unsupervised Spectrogram Cross-Correlation Method to Assess ELM Triggering Efficiency by Pellets

et al. 2022

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The high confinement mode (H-mode) is considered the optimal regime for the production of energy through nuclear fusion for industrial purposes since it allows to increase the energy confinement time of the plasma roughly by a factor of two. Consequently, it has been selected at the moment as the standard scenario for the next generation of devices, such as ITER. However, pressure-driven edge instabilities, known as edge localized modes (ELMs), are a distinct feature of this plasma regime. Their extrapolated thermal and particle peak loads on the plasma-facing components (PFC) of the next generation of devices are expected to be so high as to damage such structures, compromising the normal operations of the reactors themselves. Consequently, the induced loads have to be controlled; this can be achieved by mitigating ELMs. A possibility then lays in increasing the ELMs frequency to lower the loads on the PFCs. As already demonstrated at JET, the pellet pacing of ELMs is considered one of the most promising techniques for such scope, and its optimization is therefore of great interest for present and future operations of nuclear fusion facilities. In this work, we suggest a method to access primary pieces of information to perform statistics, assess and characterize the pacing efficiency. The method, tested on JET data, is based on the clustering (k-means) of convoluted signals, using so-called spectrogram cross-correlation, between the measured pellets and ELMs time traces. Results have also been obtained by taking advantage of a new type of diagnostic for measuring the ELMs dynamic, based on synthetic diamond sensors, faster than the standard spectroscopic cameras used at JET.

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CVD diamond photodetectors for FTU plasma diagnostics

Cited by 11 publications

References 10 publications

A new indirect measurement method of the electron temperature for the Proto-sphera's pinch plasma

A new indirect measurement method of the electron temperature for the Proto-sphera's pinch plasma

CVD diamond detectors for fast VUV and SX-ray diagnostics on FTU

An Unsupervised Spectrogram Cross-Correlation Method to Assess ELM Triggering Efficiency by Pellets

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