Reconstruction Activities And First Results From The Thomson Scattering Diagnostic On The Tcabr Tokamak

An incoherent and infrared Thomson scattering diagnostic (ITS) was transferred from ISTTOK (Lisboa) and reconstructed on TCABR (S. Paulo). In the first phase of this international collaboration, the diagnostic uses a Neodymium:Glass laser with up to 10 Joules per laser pulse and a first generation polychromator with three pairs of interference filters and avalanche photodiodes. It measures 90° scattered radiation in a single volume of observation with a single laser pulse to obtain the instant plasma electron temperature. This paper reports the reconstruction activities already carried out and presents the first experimental results. These activities include: new data model performance, laser refurbishing, new laser delivery system, stray-light reduction in the vacuum vessel, new collection lens and relative diagnostic calibration. A long run of experiments with this diagnostic shows consistency and coherence with the other TCABR diagnostics and gives indications to be able to contribute effectively to the Alfven heating program of this tokamak. © 2010 IOP Publishing Ltd.227Alonso, M.P., Wilcock, P.D., Varandas, C.A.F., (1999) Rev. Sci. Inst., 70 (1), p. 783Alonso, M.P., Berni, L., Severo, J.H., Borges, F.O., Elizondo, J.I., MacHida, M., Varandas, C.A.F., Galvo, R.M.O., (2008) Plasma Fusion. Sci., 996, p. 192Alonso, M.P., Figueiredo, A.C.A., Berni, L.A., Varandas, C.A.F., (2008) Plas. Sci. IEEE Trans. Plasma Sci., 36 (4), p. 11094Bellintani, J.V., Elfimov, A.G., Elizondo, J.I., Fagundes, A.N., Fonseca, A.M.M., Galvo, R.M.O., Guidolin, L., MacHida, M., (2006), 875, p. 350Berni, L.A., Alonso, M.P., Oliveira, R.M., (2004) Rev. Sci. Inst., 75 (10), p. 388

Alfvén wave heating and runaway discharges in the TCABR tokamak

Recent results of experiments on Alfvén wave heating and runaway discharges carried out in the TCABR tokamak are presented. A new antenna type has been installed to allow wave excitation with higher RF currents and lower dynamic polarization of the antenna straps than for the one previously used. In spite of edge plasma heating, which causes influx of impurities, we have obtained a clear confirmation of wave deposition inside the plasma from a localized increase of the electron temperature measured with the ECE radiometer. Detailed profiles of the plasma density and Ha emission were obtained in runaway disharges with currents around 100 kA. These profiles confirm our model of a low-temperature plasma maintained in equilibrium by the relativistic electron beam. Analysis of the Ha and density spikes indicate that recombination plays a substantial role in the particle and energy balance

Error Analysis In The Electron Temperature Measurements In Tcabr

An analytical method is proposed to evaluate the experimental uncertainty in the electron temperature measurements in the TCABR tokamak. Solving the integral equation resulting from the convolution of two functions, one representing, the scattered light and the other the spectral apparatus function, i.e., the polychromator, an analytical expression for the electron temperature is obtained, from which the uncertainty in the measured value is readily evaluated. The results show that the major contribution to the error comes from the noise in the signal; the uncertainties in the filters parameters do not contribute significantly to the total error.3701 Instituto de Fisica del Plasma (INFIP),Cons. Nac. Invest. Cient. Tec. (CONICET),Comision Nacional de Energia Atomica (CNEA),Agencia Nacional de Promocion Cientifica y Tecnologica (ANPCyT),Centro Latino-Americano de Fisica (CLAF)Ruchko, L.F., (2002) Braz. J. Phys., 32 (1), pp. 57-64Nascimento, I.C., (2005) Nucl. Fusion, 45, p. 796Nascimento, I.C., (2007) Nucl. Fusion, 47, p. 1570Severo, J.H.F., Tsypin, V.S., Galvão, R.M.O., Nascimento, I.C., Tendler, M., Fagundes, A.N., (2002) Braz. J. Phys, 32 (1), pp. 13-19Severo, J.H.F., Nascimento, I.C., Tsypin, V.S., Galvão, R.M.O., (2003) Nucl. Fusion, 43, pp. 1047-1056Severo, J.H.F., (2009) Nucl. Fusion, 49, p. 115026Severo, J.H.F., Nascimento, I.C., Tsypin, V.S., Kuznetov, Yu.K., Saettone, E.A., Vannucci, A., Galvão, R.M.O., Mikhailovskii, A.B., (2004) Phys. Plasma, 11 (2), pp. 846-848Alonso, M.P., Figueiredo, A.C.A., Borges, F.O., Elizondo, J.I., Galvão, R.M.O., Severo, J.H.F., Usuriaga, O.C., Machida, M., (2010) Rev. Sci. Inst., 81, pp. 10D529Severo, J.H.F., Nascimento, I.C., Kuznetov, Yu.K., Tsypin, V.S., Galvão, R.M.O., Tendler, M., (2007) Rev. Sci Inst., 78, p. 043509Alonso, M.P., (2010) J. Phys.: Conf. Series, 227, p. 012027Forrest, M.J., Peacock, N.J., Robinson, D.C., Sannikov, V.V., Wilcock, P.D., (1970) Culham Plasma Physics Laboratory Report CLM-R 107, , AbingdonAnashin, A.M., Gorbunov, E.P., Ivanov, D.P., Lysenko, S.E., Peacock, N.J., Robinson, D.C., Sannikov, V.V., Strelkov, V.S., (1971) Sov. Phys. - JETP, 33, p. 1127Rautian, S.G., (1958) Sov. Phys. Uspekhi, 66 (1), p. 245Alonso, M.P., Figueiredo, A.C.A., Berni, L.A., Varandas, C.A.F., (2008) IEEE Trans. Plasma Sci., 36 (4), p. 1094Sheffield, J., (1975) Plasma Scattering of Electromagnetic Radiation, , New York: Academic pres

Overview Of Recent Results Of Tcabr

An overview of recent results obtained in TCABR is presented. Experiments on Alfvén wave heating have been carried out in both low and high density regimes. Controlling the density rise usually observed in Alfvén heating experiments, it was possible to get a clear confirmation of electron temperature increase in low-density discharges. In the high density regime, the Alfvén wave absorption occurs at mode numbers quite different from those for low density. Detailed experiments have been carried out on the transition between low and high-density confinement regimes, triggered by electrostatic polarization at the plasma edge. The results indicate that the flatness of the density profile and the decrease of edge recycling depend strongly on the level of MHD activity during transition. A preliminary analysis of the electromagnetic emission associated with the relaxation instability in the new regime of runaway discharges discovered in TCABR shows that the observations are coherent with theoretical models. The heat transport in the presence of large magnetic islands has been investigated, in the collisional regime, and found to be properly described by the Fitzpatrick model. Finally, two diagnostic techniques have been further improved, the determination of the position of the local Alfvén resonance by microwave reflectometry and the determination of the temperature and density at the plasma edge by the method based upon the uniqueness of the particle confinement time, determined from the hydrogen Balmer series emission. © 2006 American Institute of Physics.87535035