Experimental study on beam acceleration with combined NBI heating and second-harmonic ICRF heating in JT-60

Kimura, Hiroyuki; Fujii, T.; Tobita, K.; Yamagiwa, Mitsuru; Hamamatsu, K.; Saigusa, M.; Azumi, M.; Hosogane, N.; Kobayashi, Noriyuki; Kusama, Y.; Mizuno, M.; Nagashima, Takashi; Nemoto, M.; Ninomiya, H.; Takeuchi, Hiroshi; Takizuka, T.; Yoshino, R.; Team, Jt

doi:10.1088/0029-5515/31/1/008

Cited by 19 publications

(9 citation statements)

References 10 publications

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“…Fast wave second harmonic heating from the low field side can also accelerate beam ions above the injection energy, as shown with the charge exchange diagnostics for hydrogen beam ions in JT-60 [132,136,1371 and for deuterium beam ions in PLT [log], ASDEX [138], JET [139, 1401 and TFTR [141], Active charge exchange measurements show that the energetic particles are concentrated near the centre of the plasma [137]. In JET, fusion gamma ray measurements indicate deuterium energies in excess of 1.7 MeV during second harmonic heating of deuterium beam ions [54].6 Gamma ray spectra for hydrogen minority heating with and without beam injection are shown in Fig.…”

Section: Ion Cyclotron Range Of Frequenciesmentioning

confidence: 99%

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The behaviour of fast ions in tokamak experiments

1994

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ABSTRACT. Fast ions with energies significantly larger than the bulk ion temperature are used to heat most tokamak plasmas. Fast ion populations created by fusion reactions, by neutral beam injection and by radiofrequency (RF) heating are usually concentrated in the centre of the plasma. The velocity distribution of these fast ion populations is determined primarily by Coulomb scattering; during wave heating, perpendicular acceleration by the RF waves is also important. Transport of fast ions is typically much slower than thermal transport, except during MHD events. Intense fast ion populations drive collective instabilities. Implications for the behaviour of alpha particles in future devices are discussed.

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Section: Ion Cyclotron Range Of Frequenciesmentioning

confidence: 99%

“…Perhaps the most straightforward test of second harmonic heating theory was performed by injecting near perpendicular hydrogen beams into JT-60 while applying ICRF [132,137,2381. Active charge exchange measurements indicate strong heating above the injection energy (Fig.…”

Section: Icrf Wavesmentioning

confidence: 99%

The behaviour of fast ions in tokamak experiments

1994

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“…Adding radio frequency (RF) power leads to interaction between wave electric field and NBI ions, providing the wave particle resonance condition is satisfied, and this process further modifies the fast ion distribution function (FI DF). This phenomenon is commonly referred to as 'synergistic effects' and it has been a subject of intensive studies as reported in [1][2][3][4][5][6][7][8][9] and more recently in [10][11][12][13]. Better understanding of the physics involved in fast ion (FI) synergistic effects is important for dealing with two essential issues in present fusion research: (i) improving the beam-target (BT) fusion performance measured by the BT neutron rate in stable plasma conditions and (ii) mitigating the negative effect of the interactions between highly energetic particles and various MHD modes.…”

Section: Introductionmentioning

confidence: 99%

Fast ion synergistic effects in JET high performance pulses

et al. 2019

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Fast ion synergistic effects were studied by predictive modelling of JET best performing pulses for various levels of neutral beam injection (NBI) and radio frequency (RF) power. Calculated DD neutron yields were analysed with the intention of separating the impact of RF synergistic effects due to changes in fast ion (FI) distribution function (DF) from secondary effects accompanying the application of RF power, namely changes in Te and Ti. A novel approach in analysing the efficiency of fast ions in fusion reactions based on evaluation of the cumulative reaction rates is outlined and used in the study. Conclusions on the impact of fast ion synergistic effects on fusion performance are based on comparisons of beam-target (BT) and thermal (Th) DD reaction rates. It was found that changes in auxiliary heating power, NBI and RF, by 4 MW will affect DD fusion performance and neutron rates significantly. Simulations of the best performing JET pulses show that for H minority RF heating scheme with available RF power the impact of RF synergistic effects is somewhat lesser than the secondary effects related to changes in Te and Ti. In conditions of much higher RF power the modification in fast ion distribution function (FI DF) and the impact of the fast ions on BT DD fusion becomes significant. The impact of the RF and NBI power on the BT reactivities was found to be of similar order; however, the NBI power has greater impact on reaction rates due to its larger effect on fast ion density.

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“…One of the most interesting applications of the CNS to ASDEX Upgrade plasmas is the investigation of the synergy effect between NBI and the Ion Cyclotron Resonance Heating [13,14]. It is a common observation in tokamaks that adding radio-frequency heating on top of NBI enhances the neutron rate by more than the rate associated with ICRH only under the same experimental conditions and plasma parameters [15].…”

Section: Jinst 7 C03004mentioning

confidence: 99%

First neutron spectrometry measurements in the ASDEX Upgrade tokamak

et al. 2012

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A compact neutron spectrometer based on the liquid scintillator BC501A has been installed on the ASDEX Upgrade tokamak. The aim is to measure neutron energy distribution functions as footprints of fast ions distribution functions, generated mainly via Neutral Beam Injection (NBI) in present day tokamaks. A flexible and fast software has been developed to perform digital pulse shape separation and to evaluate pulse height spectra. First measurements of count rates and pulse height spectra show a good signal to noise ratio for integration times comparable to the NBI slowing down time and to the energy confinement time. Due to the perpendicular line of sight, D-d fusion with perpendicular NBI is detected more efficiently and the line broadening of the 2.45 MeV neutrons is higher. Ion Cyclotron Resonance Heating (ICRH) combined to NBI exhibits a synergy effect, with count rates higher than the sum of the counts due to NBI and ICRH separately. Although the collimator is designed to screen gammas as much as possible, some qualitative gamma analysis is also possible, providing information in case of runaway electrons during disruptions. The experimental campaign for the characterisation of the system (detector + acquisition system) is complete and the determination of the response function is in progress.

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Experimental study on beam acceleration with combined NBI heating and second-harmonic ICRF heating in JT-60

Cited by 19 publications

References 10 publications

The behaviour of fast ions in tokamak experiments

The behaviour of fast ions in tokamak experiments

Fast ion synergistic effects in JET high performance pulses

First neutron spectrometry measurements in the ASDEX Upgrade tokamak

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