Energetic ion transport by abrupt large-amplitude event induced by negative-ion-based neutral beam injection in the JT-60U

To investigate energetic ion transport induced by bursting modes in the frequency range of Alfvén eigenmodes, which is called abrupt large-amplitude events (ALEs) driven by negative-ion-based neutral beam (N-NB) injection, neutron emission profile measurement and charge exchange (CX) neutral particle (flux) measurement using a natural diamond detector have been performed simultaneously in JT-60U. It is found from the CX neutral particle (flux) measurement that energetic neutral particles in a limited energy range (100–370 keV) are enhanced due to ALEs, and the neutron radial profile is flattened. The change in the energetic ion density profile inferred from these measurements indicates that ALEs expel energetic ions from the core region of the plasma and induce both redistribution and loss of energetic ions. It has been shown that the energy range of transported energetic ions is consistent with a resonance condition between energetic ions and ALEs, and the energetic ion transport results from the resonant interaction between energetic ions and ALEs. Further, a fraction of the energetic ion loss has been quantitatively estimated to be ∼4%.

[1]  A. V. Krasilnikov,et al.  Charge exchange neutral particle measurements with natural diamond detector under the deuterium–deuterium neutron field on JT-60U tokamak , 2004 .

[2]  M. Nagami,et al.  First measurement of neutron emission profile on JT-60U using Stilbene neutron detector with neutron-gamma discrimination , 2002 .

[3]  T. Ozeki,et al.  Recent progress of Alfvén eigenmode experiments using N-NB in JT-60U tokamak , 2002 .

[4]  M. Takechi,et al.  Alfvén eigenmodes driven by Alfvénic beam ions in JT-60U , 2001 .

[5]  T. Fujita,et al.  Characteristics of Alfvén eigenmodes, burst modes and chirping modes in the Alfvén frequency range driven by negative ion based neutral beam injection in JT-60U , 1999 .

[6]  S. S. Medley,et al.  Neutron and Fast Atom Spectrometry Using Natural Diamond Detectors , 1999 .

[7]  A. V. Krasilnikov,et al.  Natural diamond detector as a high energy particle spectrometer , 1997 .

[8]  T. Nishitani,et al.  Neutral particle analysis in MeV energy range and relative role of and ions in fast proton neutralization in ICRF and combined ICRF/NBI-heated JT-60U plasmas , 1997 .

[9]  O. Naito,et al.  Nondimensional Transport Study of JT-60U Plasmas , 1995 .

[10]  Masayasu Sato,et al.  Investigation of high-n TAE modes excited by minority-ion cyclotron heating in JT-60U , 1995 .

[11]  E. Strait,et al.  Doppler shift of the TAE mode frequency in DIII-D , 1994 .

[12]  Liu Chen,et al.  Theory of magnetohydrodynamic instabilities excited by energetic particles in tokamaks , 1994 .

[13]  C. Barnes,et al.  Absolute calibration of the JT‐60U neutron monitors using a 252Cf neutron sourcea) , 1992 .

[14]  H. Bosch,et al.  ERRATUM: Improved formulas for fusion cross-sections and thermal reactivities , 1992 .

[15]  Paul,et al.  Excitation of toroidal Alfvén eigenmodes in TFTR. , 1991, Physical review letters.

[16]  D. Mikkelsen.  Approximation for non-resonant beam target fusion reactivities , 1989 .

[17]  M. S. Chance,et al.  Low-n shear Alfven spectra in axisymmetric toroidal plasmas , 1986 .

[18]  Robert J. Goldston,et al.  Theory of mode-induced beam-particle loss in tokamaks , 1983 .

[19]  Keiji Tani,et al.  Effect of Toroidal Field Ripple on Fast Ion Behavior in a Tokamak , 1981 .