Francesco Orsitto
ENEA Frascati, Italy

"Pulsed Polarimetry: A technique for measuring electron temperature in fusion reactor plasmas"

Pulsed Polarimetry or Polarimetric Thomson scattering (PTS) is a novel technique for measuring electron temperature in HOT (Te>10keV) FUSION PLASMAS by measuring the depolarization of scattered radiation instead of its spectrum(Incoherent Thomson Scattering,ITS)[1]. The depolarization is proportional to the electron temperature. Being a polarimetric measurement, in the simplest configuration two signals are measured. However, while the Theoretical basis is almost completed [1-5], PTS needs a feasibility test. The test on FTU( Frascati Tokamak Upgrade) is under study, PTS measurement can lead to a reasonable accuracy (10-20%) on Te measurement [6].

The seminar starts from the basic elements of polarimetry measurements, (i.e. the Stokes vectors and their measurements); the elements of the Incoherent Thomson scattering are then recalled. The development of the Theory of Polarimetric Thomson Scattering is traced with application to the evaluations to ITER and FTU PTS. Technical details related to the optical components are also briefly discussed.

1. F.P. Orsitto and N. Tartoni, Rev Sci Instr 70 (1999) 79; F.P. Orsitto - PULSED POLARIMETRY - International Conference Frontiers in Diagnostics Technologies Frascati (Italy) April 2016
2. L. Giudicotti, M. Bassan, F. P. Orsitto, R. Pasqualotto, M. Kempenaars and J. C. Flanagan, LAPD17- Conceptual study of a polarimetric Thomson scattering diagnostic in ITER - JINST 1 (2016) 17th LAPD
3. S.E. Segre and V. Zanza, Phys Plasmas 7 (2000) 2677
4. V.V. Mirnov et al, IAEA-FEC 2012, San Diego ITR/P5-32; and Rev Sci Instr 5 (2014) 11D302
5. E. Parke, et al, JINST 9 (2014) C02030
6. P. Pizzolati, et al, Rev Sci Instr 63 (1992); F.P Orsitto, et al, Rev Sci Instr 66 (1995) 1167; F.P. Orsitto, et al, Appl Optics 34 (1995) 2712

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