title: New detection system and signal processing for the tokamak ISTTOK heavy ion beam diagnostic.
abstract: The tokamak ISTTOK havy ion beam diagnostic (HIBD) operates with a multiple cell array detector (MCAD) that allows for the plasma density and the plasma density fluctuations measurements simultaneously at different sampling volumes across the plasma. To improve the capability of the plasma density fluctuations investigations, a new detection system and new signal conditioning amplifier have been designed and tested. The improvements in MCAD design are presented which allow for nearly complete suppression of the spurious plasma background signal by applying a biasing potential onto special electrodes incorporated into MCAD. The new low cost and small size transimpedance amplifiers are described with the parameters of 400 kHz, 10(7) V/A, 0.4 nA of RMS noise, adequate for the plasma density fluctuations measurements.
authors.affiliation: Associação Euratom/IST, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade Técnica de Lisboa, Portugal. rhenriques@ipfn.ist.utl.pt
authors.forename: R B
authors.initials: RB
authors.lastname: Henriques
authors.forename: I S
authors.initials: IS
authors.lastname: Nedzelskiy
authors.forename: A
authors.initials: A
authors.lastname: Malaquias
authors.forename: H
authors.initials: H
authors.lastname: Fernandes