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Title: Fast ion energy distribution from third harmonic radio frequency heating measured with a single crystal diamond detector at the Joint European Torus

Abstract

Neutron spectroscopy measurements with a single crystal diamond detector have been carried out at JET, for the first time in an experiment aimed at accelerating deuterons to MeV energies with radio frequency heating at the third harmonic. Data are interpreted by means of the expected response function of the detector and are used to extract parameters of the highly non-Maxwellian distribution function generated in this scenario. A comparison with observations using a time of flight and liquid scintillator neutron spectrometers is also presented. The results demonstrate the capability of diamond detectors to contribute to fast ion physics studies at JET and are of more general relevance in view of the application of such detectors for spectroscopy measurements in the neutron camera of next step tokamak devices.

Authors:
; ;  [1];  [2];  [2];  [1];  [2];  [3]; ; ;  [1];  [2]; ;  [1];  [4];  [1];  [3];  [5]
  1. EUROfusion Consortium, JET, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom)
  2. (Italy)
  3. (United Kingdom)
  4. (Sweden)
  5. (EUROfusion Consortium, JET, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom)
Publication Date:
OSTI Identifier:
22482556
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 86; Journal Issue: 10; Other Information: (c) 2015 EURATOM; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; DEUTERONS; DIAMONDS; DISTRIBUTION FUNCTIONS; ENERGY SPECTRA; IONS; JET TOKAMAK; MONOCRYSTALS; NEUTRON CAMERAS; NEUTRON SPECTROMETERS; NEUTRON SPECTROSCOPY; RADIOWAVE RADIATION; RESPONSE FUNCTIONS; TIME-OF-FLIGHT METHOD

Citation Formats

Nocente, M., Rebai, M., Gorini, G., Dipartimento di Fisica “G. Occhialini,” Università degli Studi di Milano-Bicocca, Milano, Istituto di Fisica del Plasma “P. Caldirola,” Consiglio Nazionale delle Ricerche, Milano, Cazzaniga, C., Istituto di Fisica del Plasma “P. Caldirola,” Consiglio Nazionale delle Ricerche, Milano, Rutherford Appleton Laboratory, ISIS Facility, Didcot, Tardocchi, M., Giacomelli, L., Muraro, A., Istituto di Fisica del Plasma “P. Caldirola,” Consiglio Nazionale delle Ricerche, Milano, Binda, F., Eriksson, J., Department of Physics and Astronomy, Uppsala University, Uppsala, Sharapov, S., CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, and Collaboration:. Fast ion energy distribution from third harmonic radio frequency heating measured with a single crystal diamond detector at the Joint European Torus. United States: N. p., 2015. Web. doi:10.1063/1.4931755.
Nocente, M., Rebai, M., Gorini, G., Dipartimento di Fisica “G. Occhialini,” Università degli Studi di Milano-Bicocca, Milano, Istituto di Fisica del Plasma “P. Caldirola,” Consiglio Nazionale delle Ricerche, Milano, Cazzaniga, C., Istituto di Fisica del Plasma “P. Caldirola,” Consiglio Nazionale delle Ricerche, Milano, Rutherford Appleton Laboratory, ISIS Facility, Didcot, Tardocchi, M., Giacomelli, L., Muraro, A., Istituto di Fisica del Plasma “P. Caldirola,” Consiglio Nazionale delle Ricerche, Milano, Binda, F., Eriksson, J., Department of Physics and Astronomy, Uppsala University, Uppsala, Sharapov, S., CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, & Collaboration:. Fast ion energy distribution from third harmonic radio frequency heating measured with a single crystal diamond detector at the Joint European Torus. United States. doi:10.1063/1.4931755.
Nocente, M., Rebai, M., Gorini, G., Dipartimento di Fisica “G. Occhialini,” Università degli Studi di Milano-Bicocca, Milano, Istituto di Fisica del Plasma “P. Caldirola,” Consiglio Nazionale delle Ricerche, Milano, Cazzaniga, C., Istituto di Fisica del Plasma “P. Caldirola,” Consiglio Nazionale delle Ricerche, Milano, Rutherford Appleton Laboratory, ISIS Facility, Didcot, Tardocchi, M., Giacomelli, L., Muraro, A., Istituto di Fisica del Plasma “P. Caldirola,” Consiglio Nazionale delle Ricerche, Milano, Binda, F., Eriksson, J., Department of Physics and Astronomy, Uppsala University, Uppsala, Sharapov, S., CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, and Collaboration:. 2015. "Fast ion energy distribution from third harmonic radio frequency heating measured with a single crystal diamond detector at the Joint European Torus". United States. doi:10.1063/1.4931755.
@article{osti_22482556,
title = {Fast ion energy distribution from third harmonic radio frequency heating measured with a single crystal diamond detector at the Joint European Torus},
author = {Nocente, M. and Rebai, M. and Gorini, G. and Dipartimento di Fisica “G. Occhialini,” Università degli Studi di Milano-Bicocca, Milano and Istituto di Fisica del Plasma “P. Caldirola,” Consiglio Nazionale delle Ricerche, Milano and Cazzaniga, C. and Istituto di Fisica del Plasma “P. Caldirola,” Consiglio Nazionale delle Ricerche, Milano and Rutherford Appleton Laboratory, ISIS Facility, Didcot and Tardocchi, M. and Giacomelli, L. and Muraro, A. and Istituto di Fisica del Plasma “P. Caldirola,” Consiglio Nazionale delle Ricerche, Milano and Binda, F. and Eriksson, J. and Department of Physics and Astronomy, Uppsala University, Uppsala and Sharapov, S. and CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB and Collaboration:},
abstractNote = {Neutron spectroscopy measurements with a single crystal diamond detector have been carried out at JET, for the first time in an experiment aimed at accelerating deuterons to MeV energies with radio frequency heating at the third harmonic. Data are interpreted by means of the expected response function of the detector and are used to extract parameters of the highly non-Maxwellian distribution function generated in this scenario. A comparison with observations using a time of flight and liquid scintillator neutron spectrometers is also presented. The results demonstrate the capability of diamond detectors to contribute to fast ion physics studies at JET and are of more general relevance in view of the application of such detectors for spectroscopy measurements in the neutron camera of next step tokamak devices.},
doi = {10.1063/1.4931755},
journal = {Review of Scientific Instruments},
number = 10,
volume = 86,
place = {United States},
year = 2015,
month =
}
  • First simultaneous measurements of deuterium-deuterium (DD) and deuterium-tritium neutrons from deuterium plasmas using a Single crystal Diamond Detector are presented in this paper. The measurements were performed at JET with a dedicated electronic chain that combined high count rate capabilities and high energy resolution. The deposited energy spectrum from DD neutrons was successfully reproduced by means of Monte Carlo calculations of the detector response function and simulations of neutron emission from the plasma, including background contributions. The reported results are of relevance for the development of compact neutron detectors with spectroscopy capabilities for installation in camera systems of present andmore » future high power fusion experiments.« less
  • Joint European Torus high energy neutral particle analyzer measures the flux of fast neutrals originating from the plasma core. From this data, the fast ion distribution function f{sub i}{sup fast}, temperature T{sub i,perpendicular}{sup fast}, and density n{sub i}{sup fast} are derived using knowledge of various plasma parameters and of the cross section for the required atomic processes. In this article, a systematic sensitivity study of the effect of uncertainties in these quantities on the evaluation of the neutral particle analyzer f{sub i}{sup fast}, T{sub i,perpendicular}{sup fast}, and n{sub i}{sup fast} is reported. The dominant parameter affecting n{sub i}{sup fast} ismore » the impurity confinement time and therefore a reasonable estimate of this quantity is necessary to reduce the uncertainties in n{sub i}{sup fast} below 50%. On the other hand, T{sub i,perpendicular}{sup fast} is much less sensitive and can certainly be provided with an accuracy of better than 10%.« less
  • Wave-particle interaction phenomena in the Alfven Eigenmode (AE) frequency range are investigated at the Joint European Torus [P. H. Rebut and B. E. Keen, Fusion Technol. 11, 13 (1987)] using active and passive diagnostic methods. Fast particles are generated by neutral beam injection, ion cyclotron resonance heating, and fusion reactions. External antennas are used to excite stable AEs and measure fast particle drive and damping separately. Comparisons with numerical calculations lead to an identification of the different damping mechanisms. The use of the active AE diagnostic system to generate control signals based on the proximity to marginal stability limits formore » AE and low-frequency magnetohydrodynamic (MHD) modes is explored. Signatures of the different nonlinear regimes of fast particle driven AE instabilities predicted by theory are found in the measured spectra. The diagnostic use of AE measurements to get information both on the plasma bulk and the fast particle distribution is assessed. (c) 2000 American Institute of Physics.« less
  • In Joint European Torus (JET) [P. J. Lomas, Plasma Phys. Controled Fusion 31, 1481 (1989)], discharges with ion cyclotron resonance heating only, low-density plasmas and high fast ions energy contents provided a scenario where fishbones behavior has been observed to be related with sawtooth activity: Crashes of monster sawteeth abruptly changed the type of observed fishbones from low-frequency fishbones [B. Coppi and F. Porcelli, Phys. Rev. Lett. 57, 2272 (1986)] to high-frequency fishbones [L. Chen, R. White, and M. Rosenbluth, Phys. Rev. Lett. 52, 1122 (1984)]. During periods between crashes, the type of observed fishbones gradually changed in the oppositemore » way. Two new fishbones regimes have been observed in intermediate stages: Fishbones bursts covering both high and low frequencies and low amplitude bursts of both types occurring simultaneously. Both sawtooth and fishbones behavior have been explained using a variational formalism.« less