title: Monitoring Alfvén cascades with interferometry on the JET Tokamak.
abstract: A microwave interferometry technique is applied for the first time for detecting a discrete spectrum of Alfvén cascade (AC) eigenmodes excited with fast ions in reversed magnetic shear plasmas of the Joint European Torus. The interferometry measurements of plasma density perturbations associated with ACs show an unprecedented frequency and time resolution superior to that obtained with external magnetic coils. The measurements of ACs are used for monitoring the evolution of the safety factor and density of rational magnetic surfaces in the region of maximum plasma current.
authors.affiliation: Euratom/UKAEA Fusion Association, Culham Science Centre, Abingdon OX14 3DB, United Kingdom.
authors.forename: S E
authors.initials: SE
authors.lastname: Sharapov
authors.forename: B
authors.initials: B
authors.lastname: Alper
authors.forename: J
authors.initials: J
authors.lastname: Fessey
authors.forename: N C
authors.initials: NC
authors.lastname: Hawkes
authors.forename: N P
authors.initials: NP
authors.lastname: Young
authors.forename: R
authors.initials: R
authors.lastname: Nazikian
authors.forename: G J
authors.initials: GJ
authors.lastname: Kramer
authors.forename: D N
authors.initials: DN
authors.lastname: Borba
authors.forename: S
authors.initials: S
authors.lastname: Hacquin
authors.forename: E
authors.initials: E
authors.lastname: De La Luna
authors.forename: S D
authors.initials: SD
authors.lastname: Pinches
authors.forename: J
authors.initials: J
authors.lastname: Rapp
authors.forename: D
authors.initials: D
authors.lastname: Testa