Abstract
Thomson scattering is among one of the primary diagnostics used for tokamak plasma temperature and density measurements. Spuriously scattered stray signal further deteriorates the already existing poor signal-to-noise ratio in this technique. The present paper reports experimental investigations on the angular distribution of the scattered/stray radiation from graphite and a stack of laser blades dumps for different angles of incidence. Experimental results show a dependence of the stray signal on the dump-edge orientation. It is found that horizontally oriented dump edge produces a minimum level of stray light (around two orders less than in case of plane graphite tiles) in the horizontal plane, in which detectors for most of the diagnostics are installed. Studies are also made for p-polarized and s-polarized incident laser beams of 632.8 nm and 1064 nm wavelengths.
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References
I.H. Hutchinson, Principles of Plasma Diagnostics (Cambridge University Press, Cambridge, 2002)
J. Sheffield, Plasma Scattering of Electromagnetic Radiation (Academic Press, San Diego, 1975)
N.J. Peacock, D.C. Robinson, M.J. Forrest, P.D. Wilcock, V.V. Sannikov, Nature 224, 488 (1969)
K. Uchino et al., Appl. Phys. B 61, 165 (1995)
L.A. Berni, B.F.C. Albuquerque, Rev. Sci. Instrum. 81, 123504 (2010)
E.M. Hollmann, A.Y. Pigarov, R.P. Doerner, Rev. Sci. Instrum. 74, 3984 (2003)
S. Banerjee, P. Vasu, M. von Hellermann, R.J.E. Jaspers, Plasma Phys. Control. Fusion 52, 125006 (2010)
K. Kato, I.H. Hutchinson, Rev. Sci. Instrum. 57, 1242 (1986)
M. Born, E. Wolf, Principles of Optics (Pergamon, Oxford, 1993), p. 449
R. Kumar, Appl. Phys. B 90, 379 (2008)
R. Kumar, S.K. Kaura, D.P. Chhachhia, A.K. Aggarwal, Opt. Commun. 276, 54 (2007)
J.B. Keller, J. Opt. Soc. Am. 52, 116 (1962)
J. Weiner, Rep. Prog. Phys. 72, 064401 (2009)
C.L. Hsieh et al., Rev. Sci. lnstrum. 59, 1467 (1988)
Acknowledgements
The authors are thankful to Dr. V. Prahlad and Dr. H.C. Joshi for fruitful discussion and for critically evaluating the manuscript.
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Kumar, R., Singh, R. & Kumar, A. Studies on scattering of laser radiation from viewing dump in tokamak Thomson scattering system. Appl. Phys. B 108, 325–333 (2012). https://doi.org/10.1007/s00340-012-5056-z
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DOI: https://doi.org/10.1007/s00340-012-5056-z