title: Fast Thermal Helium Beam diagnostic for measurements of edge electron profiles and fluctuations.
abstract: The edge of fusion experiments is a region where strong gradients develop, together with the presence of strong fluctuations due to turbulence. The thermal helium beam diagnostic developed for the RFX-mod experiment allows the measurements with a single diagnostic of both low frequency time evolution of the edge radial profiles of electron density and temperature (tens of hertz), and the high frequency fluctuations (hundreds of kHz). To maximize the collected light, the three HeI lines necessary to be measured for the evaluation of n(e) and T(e) are separated with a spectrograph, and multianode photomultipliers are used as light detectors. The paper describes the diagnostic setup, with the interface hardware with the machine and the optical layout, and the characterization of its performances.
authors.affiliation: Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), C.so Stati Uniti 4, 35127 Padova, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Agostini
authors.affiliation: Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), C.so Stati Uniti 4, 35127 Padova, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Scarin
authors.affiliation: Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), C.so Stati Uniti 4, 35127 Padova, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Cavazzana
authors.affiliation: Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), C.so Stati Uniti 4, 35127 Padova, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Carraro
authors.affiliation: Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), C.so Stati Uniti 4, 35127 Padova, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Grando
authors.affiliation: Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), C.so Stati Uniti 4, 35127 Padova, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Taliercio
authors.affiliation: Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), C.so Stati Uniti 4, 35127 Padova, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Franchin
authors.affiliation: Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), C.so Stati Uniti 4, 35127 Padova, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Tiso