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2 results on '"Pagonakis, I."'

1. Operations with spherical calorimetric loads in different configurations at gyrotron test stands at EPFL and QST

Author

Bin, W., Bruschi, A., Fanale, F., Lucca, F., Alberti, S., Carannante, G., Cavinato, M., Goodman, T., J.-P., Hogge, Legrand, F., Sanchez, F., Koji, Takahashi, Albajar, F., Chelis, I., F., Dell'Era, Fasel, D., Gantenbein, G., Granucci, G., Ryosuke, Ikeda, Illy, S., Ioannidis, Z., Jelonnek, J., Meller, V., Minelli, Nardone, A., Yasuhisa, Oda, Pagonakis, I., Rispoli, N., Rzesnicki, T., Sartori, Silva, M., Simonetto, A., Thumm, M., Tigelis, I., Bin, W., Bruschi, A., Fanale, F., Lucca, F., Alberti, S., Carannante, G., Cavinato, M., Goodman, T., J.-P., Hogge, Legrand, F., Sanchez, F., Koji, Takahashi, Albajar, F., Chelis, I., F., Dell'Era, Fasel, D., Gantenbein, G., Granucci, G., Ryosuke, Ikeda, Illy, S., Ioannidis, Z., Jelonnek, J., Meller, V., Minelli, Nardone, A., Yasuhisa, Oda, Pagonakis, I., Rispoli, N., Rzesnicki, T., Sartori, Silva, M., Simonetto, A., Thumm, M., and Tigelis, I.

Abstract

A research activity in the Institute for Plasma Science and Technology of National Research Council (ISTP-CNR, Italy, former IFP-CNR) and in L.T. Calcoli (LTC, Italy) is aimed at the design and construction of calorimetric loads for absorption and measurement of high power millimeter-waves in the electron cyclotron frequency range. Recently, two CW 170 GHz loads, one for the European ITER gyrotron test facility and the other for the FALCON test- bed, have been installed at the Swiss Plasma Center (SPC, Switzerland). One short pulse (2 s) load for 1 MW, designed and optimised to operate at two different frequencies (84 GHz and 126 GHz), was provided for testing and conditioning two new dual-frequency gyrotrons for the Tokamak à Configuration Variable (TCV, Switzerland). Two additional CW loads, designed for absorbing powers higher than 1 MW, have been delivered to the National Institutes for Quantum and Radiological Science and Technology (QST, Japan) and exploited for the acceptance tests and the conditioning of the prototype of the Japanese ITER gyrotron. The present status and the most recent experimental results achieved in the framework of this development activity are reported in the paper.

Published
2020

2. Collective Thomson Scattering Diagnostic for Wendelstein 7-X at 175 GHz

Author

Moseev, Dmitry, Laqua, H. P., Stange, T., Abramovic, I., Nielsen, S. K., Äkäslompolo, S., Avramidis, K., Braune, H., Gantenbein, G., Illy, S., Jelonnek, J., Jin, J., Kasparek, W., Krier, L., Korsholm, S.B., Lechte, C., Marek, Ales, Marsen, S., Nishiura, M., Pagonakis, I., Salewski, M., Rasmussen, J., Tancetti, A., Thumm, M., Wolf, R. C., Moseev, Dmitry, Laqua, H. P., Stange, T., Abramovic, I., Nielsen, S. K., Äkäslompolo, S., Avramidis, K., Braune, H., Gantenbein, G., Illy, S., Jelonnek, J., Jin, J., Kasparek, W., Krier, L., Korsholm, S.B., Lechte, C., Marek, Ales, Marsen, S., Nishiura, M., Pagonakis, I., Salewski, M., Rasmussen, J., Tancetti, A., Thumm, M., and Wolf, R. C.

Abstract

The Collective Thomson Scattering (CTS) diagnostic measures the scattering spectrum of incident radiation off collective fluctuations in plasmas. In Wendelstein 7-X (W7-X) the diagnostic uses a 140 GHz heating gyrotron as a source of the probing radiation. At this frequency, the CTS spectra are heavily affected by the electron cyclotron emission, and the microwave beam propagation is restricted at typical W7-X plasma parameters. The diagnostic was successfully commissioned in the last experimental campaign and demonstrated ion temperature measurements. However, the signal-to-noise ratio was too low for measuring other quantities such as the fast-ion velocity distribution function or the fuel ion ratio. Currently, the W7-X CTS diagnostic is undergoing an upgrade to a frequency of 175 GHz. This will increase the sensitivity of the diagnostic, since the noise due to electron cyclotron emission will be reduced, and it will relax the constraints on microwave beam propagation in W7-X. Here we present the salient features of the upgraded CTS system and discuss its prospects for both thermal-ion and fast-ion measurements.

Published
2020

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