A. Gondhalekar

Culham Centre for Fusion Energy, Abingdon-on-Thames, England, United Kingdom

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Publications (81)175.43 Total impact

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    ABSTRACT: The energy confinement properties of ohmically heated JET discharges are discussed in detail, from both a local and a global point of view. Also, the plasma resistivity and poloidal field diffusion are discussed in some detail.
    Nuclear Fusion 01/2011; 28(1):73. DOI:10.1088/0029-5515/28/1/006 · 3.24 Impact Factor
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    ABSTRACT: Measurements of the suprathermal tail of the energy distribution function of deuterium ions, in plasmas containing MeV energy ICRH driven minority He3 ions and majority deuterium ions, revealed that the suprathermal tail ion density exceeded by nearly an order of magnitude that expected due to nuclear elastic scattering (NES) of He3 projectile ions on deuterium target ions. The experiments were performed on the Joint European Torus (JET), measurements of the line-of-sight integrated energy distribution functions of He3 and suprathermal deuterium ions were made using a high energy neutral particle analyzer. The NES or 'knock-on' deuterium ion energy distribution function was simulated using the FPP-3D Fokker–Plank code (Zaitsev et al 2002 Nucl. Fusion 42 1340) which solves the 3D trajectory averaged kinetic equations in JET tokamak geometry while taking into account NES of He3 ions on the deuterium ions. The required input energy distribution function of ICRH driven He3 ions was simulated using the SELFO code (Hedin et al 2002 Nucl. Fusion 42 527). The comparison between measurement and simulation in the He3 ICRH experiments is contrasted with an analogous previous comparison between measurements and simulation of JET plasmas in which 3.5 MeV DT fusion alpha-particles were the projectile ions, where measurement and simulation roughly agreed. Possible explanations for the observed excess knock-on deuterium tail in the experiments with He3 minority ICRH are discussed. The importance of D + He3 fusion products as additional drivers of suprathermal fuel ions is underlined.
    Plasma Physics and Controlled Fusion 09/2007; 49(11):1747. DOI:10.1088/0741-3335/49/11/001 · 2.39 Impact Factor
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    ABSTRACT: Ion cyclotron resonance frequencies (ICRF) mode conversion has been developed for localized on-axis and off-axis bulk electron heating on the JET tokamak. The fast magnetosonic waves launched from the low-field side ICRF antennas are mode-converted to short-wavelength waves on the high-field side of the 3He ion cyclotron resonance layer in D and 4He plasmas and subsequently damped on the bulk electrons. The resulting electron power deposition, measured using ICRF power modulation, is narrow with a typical full-width at half-maximum of ≈30 cm (i.e. about 30% of the minor radius) and the total deposited power to electrons comprises at least up to 80% of the applied ICRF power. The ICRF mode conversion power deposition has been kept constant using 3He bleed throughout the ICRF phase with a typical duration of 4–6 s, i.e. 15–40 energy confinement times. Using waves propagating in the counter-current direction minimizes competing ion damping in the presence of co-injected deuterium beam ions.
    Nuclear Fusion 01/2004; 44(1):33. DOI:10.1088/0029-5515/44/1/004 · 3.24 Impact Factor
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    ABSTRACT: Experiments with directed ICRF waves have for the first time in JET demonstrated the influence of absorbed wave momentum on bulk plasma rotation. Resonating fast ions acted as an intermediary in this process and the experiments therefore provided evidence for the effect of fast ions on the plasma rotation. Results from these experiments are reviewed together with results from ICRF heated plasmas with symmetric spectra in JET and Tore Supra. The relevance of different theoretical models is briefly considered.
    12/2003; DOI:10.1063/1.1637994
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    ABSTRACT: Plasmas heated by ICRF only in the JET tokamak show distinct structures in the toroidal rotation profile, with regions where &ddiff;ω/&ddiff;r>0 when the minority cyclotron resonance layer is far off-axis. The rotation is dominantly co-current with a clear off-axis maximum. There is only a slight difference between a high-field side (HFS) or a low-field side position of this resonance layer: the off-axis maximum in the rotation profile is modestly higher for the HFS position. This is in contrast to the predictions of theories that rely mainly on the effects arising from ICRF-driven fast ions to account for ICRF-induced plasma rotation. The differences due to the direction of the antenna spectrum (co- or counter-) are small. A more central deposition of the ICRF power in L-mode and operation in H-mode both lead to more centrally peaked profiles, both in the co-direction. Strong MHD modes brake the rotation and lead to overall flat rotation profiles.
    Nuclear Fusion 04/2003; DOI:10.1088/0029-5515/43/4/309 · 3.24 Impact Factor
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    ABSTRACT: This article describes a neutral particle analyzer/isotope separator (ISEP) developed for measurement of the relative hydrogen isotope composition of Joint European Torus (JET) plasmas. The ISEP deployed on the JET can be regarded as a prototype of an instrument proposed for measurement of the spatial profile of the ratio of the density of deuterium and tritium ions in the plasma, nD(r)/nT(r), in the International Thermonuclear Experimental Reactor (ITER). The ISEP makes simultaneous measurements of the energy distribution of efflux of hydrogen isotope atoms (H, D, and T) from the plasma. From such measurements it is possible to deduce the radial profile of the relative hydrogen isotope ion composition of the plasma and radial transport of ions of one isotope across the plasma of another isotope species. The main elements of the ISEP are (a) use of a thin carbon foil for reionization of the incident atoms, thereby eliminating gas stripping cells and gas sources of conventional neutral particle analyzers (NPAs), (b) acceleration of secondary ions in order to access the regime of higher detection efficiency of the NPA and to better separate ion pulses from neutron/γ-ray induced pulses in scintillator detectors, (c) E‖B dispersion of the secondary ions in specially designed nonuniform magnetic and electric fields to provide focusing in the detector plane, increased throughput and greater contrast between neighboring isotopes, and (d) counting of energy and mass analyzed secondary ions using detectors consisting of thin [1 ⩽ t (μm) ⩽ 7] CsI(Tl) scintillators deposited directly on miniature thin window photomultiplier tubes mounted in vacuum. The ISEP has high contrast between atoms of neighboring masses ( ≥ 103 for E ≈ 5 keV and much greater at higher energies), and high detection efficiency (0.06 ⩽ ε ⩽ 0.83 for atoms of 5 ⩽ (keV) ⩽ 150. ISEP detectors have very low sensitivity to neutrons and γ rays ( ⩽ 10−7 of ion sensitivity), making it feasible to use the ISEP in JET DT experiments without any shielding. Only a modest amount of neutron/γ-ray shielding would be required in the ITER for similar applications of the ISEP. The initial experiments on JET plasmas using the ISEP demonstrate well the capabilities of the instrument for measurement of the hydrogen isotope composition of the plasma and the energy distribution function of isotope ions. © 2003 American Institute of Physics.
    Review of Scientific Instruments 03/2003; 74(4):2338-2352. DOI:10.1063/1.1542664 · 1.58 Impact Factor
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    ABSTRACT: Internal radial redistribution of MeV energy ion cyclotron resonance frequency driven hydrogen minority ions was inferred from neutral particle analyzer measurements during large amplitude magnetohydrodynamic activity in plasmas with an internal transport barrier in the Joint European Torus. A theory is developed for energetic ion redistribution during a m=2/n=1 kink mode instability. Plasma motion during the instability or during subsequent magnetic reconnection generates an electric field which can change the energy and radial position of the energetic ions. The magnitude of ion energy change depends on the value of the safety factor at the plasma core, q(0) from which the energetic ions are redistributed. A relation is found for the corresponding change in canonical momentum PPhi, which leads to radial displacement of the ions. The model yields distinctive new features of energetic ion redistribution such as more vertical particle displacement as q(0) increases from 1 to 2. Predicted characteristics of ion redistribution are compared with the measurements, and good correlation is found. Sometimes the energetic ions were further transported to the plasma edge due to interaction with a long-lived magnetic fluctuation (often in the form of a magnetic island) with chirping frequency in the laboratory frame which developed after the m=2/n=1 kink instability. Convection of resonant ions trapped in a radially moving phase-space island is modeled to understand the physics of such events.
    Physics of Plasmas 03/2003; 10(3). DOI:10.1063/1.1539471 · 2.25 Impact Factor
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    ABSTRACT: Scientific and technical activities on JET focus on the issues likely to affect the ITER design and operation. Our understanding of the ITER reference mode of operation, the ELMy H-mode, has progressed significantly. The extrapolation of ELM size to ITER has been re-evaluated. Neoclassical tearing modes have been shown to be meta-stable in JET, and their beta limits can be raised by destabilization (modification) of sawteeth by ion cyclotron radio frequency heating (ICRH). Alpha simulation experiments with ICRH accelerated injected 4 (He) beam ions provide a new tool for fast particle and magnetohydrodynamic studies, with up to 80-90% of plasma heating by fast 4 He ions. With or without impurity seeding, a quasi-steady-state high confinement (H-98 = 1), high density(n(e)/n(GW) = 0.9-1) and high beta (betaN = 2) ELMy H-mode has been achieved by operating near the ITER triangularity ( similar to 0.40-0.5) and safety factor (q(95) similar to 3), at Z(eff) similar to 1.5-2. In advanced tokamak (AT) scenarios, internal transport barriers (ITBs) are now characterized in real time with a new criterion, rhoT(*). Tailoring of the current profile with T lower hybrid current drive provides reliable access to a variety of q profiles, lowering access power for barrier formation. Rational q surfaces appear to be associated with ITB formation. Alfven cascades were observed in reversed shear plasmas, providing identification of q profile evolution. Plasmas with 'current holes' were observed and modelled. Transient high confinement AT regimes with H-89 = 3.3, beta(N) = 2.4 and ITER-relevant q < 5 were achieved with reversed magnetic shear. Quasi-stationary ITBs are developed with full non-inductive current drive, including similar to 50% bootstrap current. A record duration of ITBs was achieved, up to 11 s, approaching the resistive time. For the first time, pressure and current profiles of AT regimes are controlled by a real-time feedback system, in separate experiments. Erosion and co-deposition studies with a quartz micro-balance show reduced co-deposition. Measured divertor thermal loads during disruptions in JET could modify ITER assumptions.
    Nuclear Fusion 01/2003; · 3.24 Impact Factor
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    ABSTRACT: Plasmas heated by ICRF only in the JET tokamak show distinct structures in the toroidal rotation profile, with regions where do/dr$>$0 when the minority cyclotron resonance layer is far off-axis. The rotation is dominantly co-current with a clear off-axis maximum. There is only a slight difference between a high-field side (HFS) or a low-field side position of this resonance layer: the off-axis maximum in the rotation profile is modestly higher for the HFS position. This is in contrast to the predictions of theories that rely mainly on the effects arising from ICRF-driven fast ions to account for ICRF-induced plasma rotation. The differences due to the direction of the antenna spectrum (co- or counter-) are small. A more central deposition of the ICRF power in L-mode and operation in H-mode both lead to more centrally peaked profiles, both in the co-direction. Strong MHD modes brake the rotation and lead to overall flat rotation profiles.
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    ABSTRACT: Experiments are conducted on the JET tokamak to demonstrate the diagnostic potential of Magneto-Hydro-Dynamics (MHD) spectroscopy, for the plasma bulk and its suprathennal components, using Alfven eigenmodes (AEs) excited by external antennas and by energetic particles. The measurements of AE frequencies and mode numbers give information on the bulk plasma. Improved equilibrium reconstruction, in particular in. terms of radial profiles of density and safety factor, is possible from the comparison between the antenna driven spectrum and that calculated theoretically. Details of the time evolution of the non-monotonic safety factor profile in advanced scenarios are reconstructed from the frequency behaviour of ICRH-driven energetic particle modes. The plasma effective mass is inferred from the resonant frequency of externally driven AEs in discharges with similar equilibrium profiles. The stability thresholds and the nonlinear development of the instabilities give clues on energy and spatial distribution of the fast particle population. The presence of unstable AEs provides lower limits in the energy of ICRH generated fast ion tails. Fast ion pressure gradients and their evolution are inferred from the stability of AEs at different plasma radial positions. Finally, the details of the AE spectrum in the nonlinear stage are used to obtain information about the fast particle velocity space diffusion.
    Plasma Physics and Controlled Fusion 12/2002; DOI:10.1088/0741-3335/44/12B/312 · 2.39 Impact Factor
  • A. Gondhalekar · P.C. Stangeby · J.D. Elder
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    ABSTRACT: Inhibition of contamination of the plasma core in JET by edge impurities during high power heating of deuterium plasmas in limiter configuration using fuelling is demonstrated. By injecting deuterium gas during heating, in the presence of a much larger recycling deuterium flux, a reduction of more than a factor of 2 was effected in n2(0)/Φ2, the ratio of central impurity density to impurity influx at the plasma edge. The reduction in n2(0) was obtained without much effect on peak electron temperature and density. Reduction of plasma contamination by gas fuelling was observed also when hot spots formed on the limiter, a condition that without simultaneous gas fuelling culminated in runaway plasma contamination. Detailed analysis of the experiments is undertaken with the purpose of identifying the processes by which plasma contamination was inhibited, employing standard limiter plasma contamination modelling. Processes which might produce the observed impurity inhibiting effects of gas injection include: (a) reduction in impurity production at the limiter; (b) increase in impurity screening in the scrape-off layer; (c) increase in radial impurity transport at the plasma edge; (d) increase in average deuteron flow velocity to the limiter along the scrape-off layer. These are examined in detail using the Monte Carlo limiter impurity transport code LIM. Bearing in mind that uncertainties exist both in the choice of appropriate modelling assumptions to be used and in the measurement of required edge plasma parameters, changes in n2(0)/Φ2, by a factor of 2 are at the limit of the present modelling capability. However, comparison between LIM code simulations and measurements of plasma impurity content indicate that the standard limiter plasma contamination model may not be adequate and that other processes need to be added in order to be able to describe the experiments in JET
    Nuclear Fusion 11/2002; 34(2):247. DOI:10.1088/0029-5515/34/2/I07 · 3.24 Impact Factor
  • K.G. McClements · R.O. Dendy · A. Gondhalekar
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    ABSTRACT: Neutral particle analyser (NPA) measurements of emitted hydrogen flux, integrated along a chord through the plasma centre, have been used to infer a perpendicular tail temperature T⊥ of minority ion cyclotron range of frequencies (ICRF) heated protons in the Joint European Torus (JET). A relation is established between T⊥ and the perpendicular proton temperature T⊥(0) at the position of maximum power deposition. At energies E >> T⊥(0), the value of T⊥ inferred from the NPA is nearly equal to T⊥(0). In the opposite limit E << T⊥(0), it is shown that T⊥ << T⊥(0). Applying this model to NPA measurements from a JET pulse with varying ICRF power PRF, it is found that the scaling of T⊥(0) with PRF in the 2 to 10 MW range is almost linear, as expected. Moreover, calculated values of the ICRF heated proton energy content, based on deduced values of T⊥(0), agree with diamagnetic measurements. The NPA measurements thus give access to a fundamental property of the heated proton energy distribution, which plays a crucial role in sawtooth stabilization
    Nuclear Fusion 10/2002; 37(4):473. DOI:10.1088/0029-5515/37/4/I05 · 3.24 Impact Factor
  • A.A. Korotkov · A. Gondhalekar · A.J. Stuart
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    ABSTRACT: A neutral particle analyser was deployed on JET for a measurement of the distribution function of megaelectronvolt energy protons driven by the high power ion cyclotron resonance frequency heating of deuterium plasmas in the hydrogen minority scheme. Unexpectedly, efficient neutralization of megaelectronvolt energy protons was observed in the plasma centre without recourse to injection of a beam of atoms to provide electron donors for charge exchange neutralization reactions. A model is presented that elucidates the role of carbon and beryllium, the main intrinsic impurities in JET plasmas, in this process and establishes charge exchange between hydrogen-like ions of the impurities and protons as the main neutralization process. A model calculation for deducing the proton energy distribution function f(Ep) from the measured hydrogen flux is described. The effects of uncertainties in neutralization cross-sections on the inferred f(Ep) are examined. The validity of this model of impurity induced neutralization (IIN) is tested by using it to describe the measured hydrogen flux in different conditions of plasma heating and fuelling. A crucial point in making these tests was to use measured local values of bare impurity ion densities; the required measurements were realized using charge exchange spectroscopy. Using IIN modelling and a procedure in which a known change in the density of deuterium atoms at the plasma centre was made by applying neutral beam injection, we have deduced the background thermal deuterium atom density at the plasma centre, which is an important new diagnostic result. Concerning future experiments, the model predicts that carbon and beryllium impurities will be major contributors to neutralization of hydrogenic ions (protons, deuterons and tritons) in ITER plasmas, for ion energies E<or=1 MeV/u. According to these estimates measurements of the distribution function, in the megaelectronvolt energy range, of ion cyclotron resonance frequency heating driven ions of hydrogen isotopes
    Nuclear Fusion 10/2002; 37(1):35. DOI:10.1088/0029-5515/37/1/I05 · 3.24 Impact Factor
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    ABSTRACT: A comprehensive set of fast particle diagnostics is routinely used at JET. Some are in the process of being upgraded and others, completely new, are being prepared for use during the forthcoming tritium experiments. For fusion product studies, the strength and profile of the charged particle birth distribution is obtained by measuring the neutron emission with three pairs of absolutely calibrated fission chambers and a two-camera profile monitor. Information on the DD neutron energy spectrum is deduced from a time-of-flight neutron spectrometer. Neutrons of 14 MeV energy from triton burnup are measured using silicon diodes and a high energy branch of the profile monitor. Absolute calibration is obtained with an activation system. A prototype lost alpha particle detector (Faraday cup) has been tested in the laboratory and has been installed inside JET so that its noise immunity can be tested. Two 14 MeV neutron spectrometers are under commissioning and a third is under construction. A high energy neutral particle analyser is routinely used to diagnose fast RF driven particles and will also be available for alpha particle studies. The intensity of RF driven fast particles is also deduced by the spectroscopy of gamma rays emitted in reactions with impurity ions in the plasma. The gamma ray measuring branch of the neutron profile monitor adds spatial resolution to the measurement. A new antenna for measuring ion cyclotron emission (ICE) and a gyrotron for alpha particle scattering experiments are in the process of being commissioned. Active charge exchange spectroscopy to investigate the low energy range of the alpha particle population is being considered. Where appropriate, information gathered with these systems is presented to illustrate their performance
    Nuclear Fusion 10/2002; 35(12):1609. DOI:10.1088/0029-5515/35/12/I24 · 3.24 Impact Factor
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    ABSTRACT: A new scenario to delay or prevent neoclassical tearing mode (NTM) onset is presented. By active sawtooth destabilization, short period and low amplitude sawteeth are generated, such that the sawtooth produced NTM seed island is reduced and the threshold normalized plasma pressure for triggering of NTMs, βNonset, is increased. The scenario has been explored experimentally in the Joint European Torus (JET). Ion cyclotron resonance frequency (ICRF) waves tuned to the 2nd harmonic H-minority resonance have been used for sawtooth control. Whereas ICRF waves generally induce sawtooth stabilization, favouring the triggering of NTMs and reducing βNonset, the present experiments show that by toroidally directed waves, ion cyclotron current drive is produced, and that sawteeth can be destabilized by careful positioning of the 2nd harmonic H resonance layer with respect to the sawtooth inversion radius. As a result, NTM onset is delayed and βNonset is increased above its value obtained in discharges with additional heating from neutral beam injection alone.
    Nuclear Fusion 10/2002; 42(11):1324. DOI:10.1088/0029-5515/42/11/306 · 3.24 Impact Factor
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    ABSTRACT: The large physical size of the JET tokamak, its heating systems and diagnostics, and its capability to operate with full deuterium-tritium (D-T) plasmas, including high-power tritium neutral beam injection (NBI), give it unique possibilities in fast particle research in fusion plasmas. These have already been used to generate significant (2-3 MW level) power in fusion α-particles in the 1997 D-T campaign. Recent JET experiments have concentrated on two important scenarios of relevance to next-step tokamak devices: the ELMy H-mode plasmas and plasmas with strong internal transport barriers (ITBs). The achieved progress will help in preparation for a possible second D-T experiment on JET. Fast particle studies have also been carried out recently using ion cyclotron resonance heating (ICRH)-accelerated particles and external-excitation methods to study Alfvén eigenmodes (AEs). Looking towards the future, the capability of JET will be enhanced by upgrades to the NBI system, ICRH system and various diagnostics. Results of the first JET D-T experiment (DTE1) form a basis on which to elaborate a second D-T experiment (DTE2) which could be proposed after these enhancements. The α-physics part of this programme would be divided between the investigation of α-particle confinement, heating and loss processes in the `integrated scenarios' (where the discharge is as close as possible to an ITER-relevant scenario), and dedicated `α-physics' experiments, with specially prepared plasmas. In ELMy H-mode plasmas the fusion performance could reach Q( = Pfusion/Pinput) of ~0.33 at the highest combined heating powers, corresponding to βα~6×10-4, allowing a test of the margins of TAE stability in quasi-steady-state conditions. The integrated-scenario fast particle programme could concentrate on the instabilities and heating in plasma regimes with strong steady-state ITBs, with expected Q values ~0.58 and βα~2×10-3, demonstrating the compatibility of these operating scenarios with α-effects. Excitation of TAEs by α-particles in the plasma core could also be studied in such integrated scenarios. An issue which will receive attention is the confinement of MeV energy ions in the centre of ITB plasmas with strongly reversed shear, where the low current density in the centre may lead to the α-particles entering loss orbits. In preparation for a D-T campaign, studies of triton burn-up in deuterium ITB plasmas will begin in the 2002 experimental campaigns. Special `afterglow' experiments to measure TAEs after the termination of the (stabilizing) NBI have already been explored in JET deuterium ITB scenarios and would be planned for DTE2. It is intended to develop special versions of ITB plasmas with dominant ion heating which would maximize the sensitivity to degradation of α-heating effects.
    Nuclear Fusion 08/2002; 42(8):1014. DOI:10.1088/0029-5515/42/8/310 · 3.24 Impact Factor
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    ABSTRACT: The properties of carbon, with respect to its ability to absorb and release hydrogen, are reviewed and applied to the interpretation of density behaviour in Ohmic-, NBI- and ICRF-heated tokamak discharges. Based on the experimental observations, improvement of H-mode parameters in JET due to reduced hydrogen re-emission from the walls is predicted with a numerical model. The particle removal rates required for Q = 1 in JET are estimated.
    Plasma Physics and Controlled Fusion 08/2002; 29(10A):1205. DOI:10.1088/0741-3335/29/10A/303 · 2.39 Impact Factor
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    ABSTRACT: Ion cyclotron heating and current drive at ω≈2ωcH in JET deuterium plasmas with a hydrogen concentration nH/(nD+nH) in the range of 5–15% are analysed, comparing results of numerical computer modelling with experiments. Second harmonic hydrogen damping is found to be maximized by placing the resonance on the low-field side (LFS) of the torus, which minimizes competing direct electron damping and parasitic high-harmonic D damping in the presence of D beams. The shape of the calculated current perturbation and the radial localization of the heating power density for the LFS resonance are consistent with the experimentally observed evolution of the sawtooth period when the resonance layer moves near the q = 1 surface. Since the calculated driven current is dominated by a current of diamagnetic type caused by finite orbit widths of trapped resonating ions, it is not too sensitive to the ICRF phasing. Control of sawteeth with ion cyclotron current drive using the LFS ω≈2ωcH resonance in the present experimental conditions can thus be best obtained by varying the resonance location rather than the ICRF phasing. Due to differences in fast ion orbits, collisional electron heating and fast ion pressure profiles are significantly more peaked for a LFS resonance than for a high-field side (HFS) resonance. For the HFS ω≈2ωcH resonance, an enhanced neutron rate is observed in the presence of D beam ions, which is consistent with parasitic D damping at the ω≈5ωcD resonance in the plasma centre.
    Plasma Physics and Controlled Fusion 07/2002; 44(8):1521. DOI:10.1088/0741-3335/44/8/307 · 2.39 Impact Factor
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    ABSTRACT: Ion cyclotron range of frequencies (ICRF) heating experiments with the third harmonic deuterium resonance in the plasma centre have been carried out at JET. These experiments were the first to demonstrate third harmonic damping on initially Maxwellian plasmas. A record deuterium-deuterium (DD) fusion reaction rate for ICRF-only heating on JET was achieved. The discharges have been simulated with the PION code (a self-consistent calculation of the evolution of the distribution function and the ICRF power deposition). To obtain reasonable agreement between the measurements and the simulations, three additions to the PION code were necessary: (a) parasitic absorption at the plasma edge, (b) a particle loss term that removes particles above 4 MeV, i.e. the particles that were not confined in the discharges, and (c) a sawtooth model that accounts in a simplified way for the redistribution of fast ions at the sawtooth crashes. According to the simulations, high energy tail formation on the distribution function of the resonating ions plays a crucial role in the power absorption.
    Nuclear Fusion 05/2002; 38(2):265. DOI:10.1088/0029-5515/38/2/310 · 3.24 Impact Factor
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    ABSTRACT: Results achieved on JET during the 1997-1999 experimental campaigns in the physics of energetic ions and runaway electrons are reviewed. Heating of deuterium-tritium (DT) plasmas by fusion born alpha particles is found to be similar to that achieved by comparable ICRF heating of deuterium plasmas. The stability of alpha particle driven Alfvén eigenmodes (AEs) in the highest fusion power ELM-free H mode discharges is shown to be consistent with the existing theoretical analysis for AEs. Direct measurements of the trapped alpha particle and knock-on deuteron distribution functions by a neutral particle analyser (NPA) are described. New ICRF heating scenarios tested in JET DT plasmas are presented in view of the possible use of the ICRF heating of ITER-like DT plasmas on route to ignition. The energetic ion pinch in the presence of toroidally asymmetric ICRF waves is studied experimentally on JET. Recent experimentally observed effects of ICRF accelerated ions on sawteeth in JET are reviewed. Detailed time and space resolved X ray images of the electron runaway beam in flight spontaneously generated by disruptions on JET are described.
    Nuclear Fusion 05/2002; 40(7):1363. DOI:10.1088/0029-5515/40/7/307 · 3.24 Impact Factor

Publication Stats

873 Citations
175.43 Total Impact Points


  • 2002–2004
    • Culham Centre for Fusion Energy
      Abingdon-on-Thames, England, United Kingdom
  • 1991–2001
    • University of Toronto
      • Institute for Aerospace Studies
      Toronto, Ontario, Canada
  • 1994
    • University of Milan
      Milano, Lombardy, Italy