The maximum likelihood reconstruction method for JET neutron tomography

The JET neutron profile monitor ensures coverage of the neutron emissive region that enables tomographic reconstruction. However, due to the availability of only two projection angles and to the coarse sampling, tomography is a limited data set problem. A reconstruction method based on the maximum likelihood principle is developed for solving the reconstruction problem. A smoothing operator, defined as median filtering which uses a sliding window moving along magnetic contour lines, is used to compensate for the lack of experimental information. The method is tested on numerically simulated phantoms with shapes characteristic for this kind of tomography. Significant reconstructions of experimental data are reported.

[1]  E. Surrey,et al.  Tritium fast ion distribution in JET current hole plasmas , 2005 .

[2]  Michael Loughlin,et al.  SPECIAL TOPIC: Neutron emission profile measurements during the first tritium experiments at JET , 1993 .

[3]  J. Lister,et al.  Investigation of the consistency of magnetic and soft X-ray plasma position measurements on TCV by means of a rapid tomographic inversion algorithm , 2003 .

[4]  K. Zastrow,et al.  NEUTRON PROFILE MEASUREMENTS FOR TRACE TRITIUM EXPERIMENTS , 1999 .

[5]  L. C. Ingesson,et al.  Soft X ray tomography during ELMs and impurity injection in JET , 1998 .

[6]  C E Floyd,et al.  Maximum likelihood reconstruction for cone beam SPECT: development and initial tests. , 1989, Physics in medicine and biology.

[7]  Jet Efda Contributors,et al.  Tritium transport experiments on the JET tokamak , 2004 .

[8]  Paul F. Fougère,et al.  Maximum Entropy and Bayesian Methods , 1990 .

[9]  G. G. Stokes.  "J." , 1890, The New Yale Book of Quotations.

[10]  Jet Efda Contributors,et al.  Overview of transport, fast particle and heating and current drive physics using tritium in JET plasmas , 2005 .

[11]  W. Linden,et al.  Maximum entropy based reconstruction of soft X-ray emissivity profiles in W7-AS , 1996 .

[12]  I. Voitsekhovitch,et al.  Neutron profiles and fuel ratio nT/nD measurements in JET ELMy H-mode plasmas with tritium puff , 2006 .

[13]  A. Murari,et al.  Gamma-ray imaging of D and 4He ions accelerated by ion-cyclotron-resonance heating in JET plasmas , 2005 .

[14]  M. Mantsinen,et al.  Comparison of basis functions in soft x-ray tomography and observation of poloidal asymmetries in impurity density , 2000 .

[15]  T.K. Fowler,et al.  Nuclear fusion , 1989, IEEE Potentials.

[16]  C. Niculae,et al.  A comparison of four tomographic methods for nuclear fuel pin analysis , 1995 .

[17]  R. Granetz,et al.  Discrepancies between soft x-ray emissivity contours and magnetic flux surfaces in Alcator C-Mod , 1996 .

[18]  A. I. Lvovsky,et al.  Iterative maximum-likelihood reconstruction in quantum homodyne tomography , 2003, quant-ph/0311097.

[19]  M. J. Mantsinen,et al.  γ-ray diagnostics of energetic ions in JET , 2002 .

[20]  G. Sadler,et al.  Neutron profile measurements in the Joint European Torus , 1997 .

[21]  M-L Mayoral,et al.  Controlling the profile of ion-cyclotron-resonant ions in JET with the wave-induced pinch effect. , 2002, Physical review letters.

[22]  R. Granetz,et al.  X-ray tomography on JET , 1988 .

[23]  G. J. Sadler,et al.  The JET neutron emission profile monitor , 1993 .

[24]  John Skilling,et al.  Maximum Entropy and Bayesian Methods , 1989 .

[25]  L. Shepp,et al.  Maximum Likelihood Reconstruction for Emission Tomography , 1983, IEEE Transactions on Medical Imaging.

[26]  P. J. Paris,et al.  X-ray tomography on the TCV tokamak , 1996 .

[27]  Physical Review , 1965, Nature.

[28]  Torbjörn Hellsten,et al.  Expanding the operating space of ICRF on JET with a view to ITER , 2006 .

[29]  E. Knill,et al.  Diluted maximum-likelihood algorithm for quantum tomography , 2006, quant-ph/0611244.