Multipoint Thomson Scattering Diagnostic For The TCABR Tokamak With Centimeter Spatial Resolution M.P. Alonso a , L. A. Berni c , J.H. Severo b , F.O. Borges b , J.I. Elizondo b , M. Machida d , C.A.F. Varandas a , R.M.O. Galvão b a Associação Euratom-IST, Instituto de Plasmas e Fusão Nuclear, Lisboa, Portugal. b Instituto de Física, Universidade de São Paulo, SP, Brazil. c Laboratório Associado de Plasma, INPE, São Jose dos Campos, SP, Brazil. d Universidade Estadual de Campinas, Campinas, SP, Brazil. Abstract. This paper describes a multi-point Thomson scattering system that is being developed for the TCABR tokamak based on a signal delay technique, which allows the determination of the electron temperature and plasma density radial profiles, with approximately 1 cm spatial resolution, employing just one spectrometer. Keywords: Thomson scattering, Tokamak, Electron temperature, Electron density. PACS: 42.55.Rz ; 42.68.Ay ; 52.38.Bv ; 52.55.Fa ; 52.70.Kz INTRODUCTION TCABR is a limiter, rectangular cross section tokamak, with major radius R 0 = 0.61 m, minor radius a = 0.18 m, toroidal magnetic field B 0 = 1.1 T, plasma current I p ≤ 100 kA, line average plasma density n ≈ 1 – 3 x 10 19 m -3 , and central electron temperature in ohmic discharges Te 0 ≤ 650 eV [1]. The TCABR Thomson scattering diagnostic has been developed aiming at providing simultaneous multipoint ne and Te measurements along one vertical chord, passing at the centre of the plasma column, with approximately 1 cm spatial resolution. The design, based upon signal delay techniques already tested on ISTTOK and ETE [2, 3], has been optimized using commercial software for optical ray-tracing. GENERAL HARDWARE DESCRIPTION This diagnostic [4, 5] is composed of a high-power laser, a laser beam delivery system, a light detection assembly and a data acquisition system (Figure 1).