title: A feasibility study of a NBI photoneutralizer based on nonlinear gating laser recirculation.
abstract: The neutralization efficiency of negative ion neutral beam injectors is a major issue for future fusion reactors. Photon neutralization might be a valid alternative to present gas neutralizers, but still with several challenges for a valid implementation. Some concepts have been presented so far but none has been validated yet. A novel photoneutralization concept is discussed here, based on an annular cavity and a duplicated frequency laser beam (recirculation injection by nonlinear gating). The choice of lithium triborate as the material for the second harmonic extractor is discussed and a possible cooling method via crystal slicing is presented; laser intensity enhancement within the cavity is evaluated in order to quantify the achievable neutralization rate. Mockups of the critical components are proposed as intermediate steps toward system realization.
authors.affiliation: Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), Corso Stati Uniti 4, 35127 Padova, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Fassina
authors.affiliation: Dipartimento di Ingegneria Elettrica, Università degli Studi di Padova, Via 8 Febbraio 1848, 2, 35122 Padova, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Pretato
authors.affiliation: Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), Corso Stati Uniti 4, 35127 Padova, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Barbisan
authors.affiliation: Dipartimento di Ingegneria Elettrica, Università degli Studi di Padova, Via 8 Febbraio 1848, 2, 35122 Padova, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Giudicotti
authors.affiliation: Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), Corso Stati Uniti 4, 35127 Padova, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Pasqualotto