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Magnetic shear reversal experiments on the Frascati Tokamak upgrade (FTU) are proposed by lower hybrid co-current drive (CD) and counter-CD. Low plasma temperatures are suggested to study relaxed states of the current density profile. In this condition LH deposition is controlled by a proper choice of plasma density and q-profile. Both simple arguments and power deposition calculations, based on ray-tracing/Fokker-Planck code, show that, at off axis, depositions useful in the co-CD scheme, are obtained. At high density, centrally peaked depositions, useful in the counter-CD scheme, are achieved. Current density diffusion calculations are performed in the presence of all the current density components (ie purely ohmic, purely non inductive and cross term). These calculations show that in the co-CD scheme, about 40%-50% of the total plasma current has to be driven non inductively, in the proper plasma position, in order to realize non-monotonic q-profiles. In the counter-CD scheme the current fraction can be even lower.

Additional information

Authors: BARBATO E, ENEA, Centro Ricerche Energia Frascati, Roma (IT)
Bibliographic Reference: Report: RT/ERG/FUS/96/25 EN (1996) 32pp.
Availability: Available from Servizio Edizioni Scientifiche, ENEA Centro Ricerche Frascati, CP65, 00044 Frascati, Roma (IT)
Record Number: 199810604 / Last updated on: 1998-05-12
Original language: en
Available languages: en