| 1. |
- Hobirk, J., et al.
(författare)
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Improved confinement in JET hybrid discharges
- 2009
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Ingår i: 36th EPS Conference on Plasma Physics 2009, EPS 2009 - Europhysics Conference Abstracts. - 9781622763368 ; , s. 150-153
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Konferensbidrag (refereegranskat)
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| 2. |
- Kiptily, V. G., et al.
(författare)
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Fusion Alpha-Particle Diagnostics for DT Experiments on the Joint European Torus
- 2014
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Ingår i: FUSION REACTOR DIAGNOSTICS. - : AIP Publishing LLC. ; , s. 87-92
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Konferensbidrag (refereegranskat)abstract
- JET equipped with ITER-like wall (a beryllium wall and a tungsten divertor) can provide auxiliary heating with power up to 35MW, producing a significant population of alpha-particles in DT operation. The direct measurements of alphas are very difficult and alpha-particle studies require a significant development of dedicated diagnostics. JET now has an excellent set of confined and lost fast particle diagnostics for measuring the alpha-particle source and its evolution in space and time, alpha-particle energy distribution, and alpha-particle losses. This paper describes how the above mentioned JET diagnostic systems could be used for alpha-particle measurements, and what options exist for keeping the essential alpha-particle diagnostics functioning well in the presence of intense DT neutron flux. Also, alpha-particle diagnostics for ITER are discussed.
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| 3. |
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| 4. |
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| 5. |
- Eriksson, Jacob, et al.
(författare)
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Finite Larmor radii effects in fast ion measurements as demonstrated using neutron emission spectrometry of JET plasmas heated with 3rd harmonic ICRF
- 2011
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Ingår i: 38th EPS Conference on Plasma Physics 2011 (EPS 2011): Europhysics Conference Abstracts. - 2914771681
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper demonstrates how the finite Larmor radii (FLR) of fast ions can affect fast ion measurements by studying data from the neutron time-of-flight spectrometer TOFOR. Neutron spectra were calculated from a model of the fast ion velocity distribution for a JET experiment with 3rd harmonic ICRF heating of deuterium beams. It was found that FLR effects need to be considered to get a good description of the data, if the Larmor radius of the fast ions are comparable to the width of the field of view of the instrument. This applies not only to results from neutron spectrometry but also to other types of fast ion diagnostics.
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| 6. |
- Eriksson, Jacob, et al.
(författare)
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Neutron spectrometry measurements of energetic deuterons in ICRF heated plasmas with the ITER-like wall at JET
- 2014
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Ingår i: 41th EPS Conference on Plasma Physics 2014 (EPS 2014): Europhysics Conference Abstracts.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- At JET, experiments have been conducted in order to optimize the performance of ion cyclotron radio-frequency (ICRF) heating in the presence of the newly installed ITER-like wall. The ICRF was tuned to the cyclotron frequency of minority hydrogen (H), which is also the 2nd harmonic of the cyclotron frequency of deuterium (D). The relative H concentration was varied from a few percent up to about 25 percent in a series of plasma discharges and the neutron time-of-flight spectrometer TOFOR was used to measure the energy spectrum of neutrons from the D(D,n)3He reaction during these discharges. It could be seen that the signal from ICRF accelerated deuterons depended strongly on H concentration. This observation indicates that the ICRF power absorbed by D at the 2nd harmonic cyclotron resonance increases with decreasing H concentration. This is in qualitative agreement with theoretical expectations obtained from the plasma wave equation solver TOMCAT.
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| 7. |
- Giacomelli, L., et al.
(författare)
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High rate measurements of the neutron camera and broadband neutron spectrometer at JET
- 2015
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Konferensbidrag (refereegranskat)abstract
- The Joint European Torus (JET, Culham, UK) is the largest tokamak in the world. JET has been upgraded over the years and recently it has also become a test facility of the components designed for ITER, the next step fusion machine under construction in Cadarache (France). At JET, the neutron emission profile of Deuterium (D) or Deuterium-Tritium (DT) plasmas is reconstructed using the neutron camera (KN3). In 2010 KN3 was equipped with a new digital data acquisition system (DAQ) based on Field Programmable Gated Array (FPGA). According to specifications, the DAQ is capable of high rate measurements up to 0.5 MCps. A new compact broadband spectrometer (KM12) based on BC501A organic liquid scintillating material was also installed in the same year and implements a similar DAQ as for KN3. This article illustrates the observations on the DAQ high count rate performance of both KN3 and KM12 in the latest JET D plasma experiments related to hybrid scenario and runaway electrons. For the latter, >1 MCps event rate was achieved with consequences on the behavior of the FPGA and on the reliability of the measurements.
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| 8. |
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| 9. |
- Gorini, Giuseppe, et al.
(författare)
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Neutron Emission from Beam-Injected Fast Tritons in JET Plasmas with Reversed or Monotonic Magnetic Shear.
- 2004
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Ingår i: 31st EPS Conference on Plasma Physics. ; , s. 4-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The neutron emission from fast tritons in plasmas with different magnetic shearconfigurations has been investigated in a dedicated experiment on JET. Short pulses ofneutral beam injection were used to deposit fast tritons in deuterium plasmas. By comparingthe measured neutron yield with predictions based on DT reaction calculations, fast tritonlosses can be assessed. The latter are expected to be very low according to neoclassicalpredictions based on Fokker-Planck simulation [1]. Much larger “anomalous” beam-ionlosses (up to 40%) have been reported in TFTR experiments for plasma conditions withreversed magnetic shear [2]. The TFTR experiments indicated an excess DT rate in thesimulation and, to a lesser extent, in the DD rate and plasma stored energy. This wasinterpreted as anomalous beam-ion loss associated with reverse shear due to an unidentifiedloss mechanism. Evidence of a similar effect was searched for in the JET experimentsreported in this paper.
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