title: Fast-particle-driven Alfvénic modes in a reversed field pinch.
abstract: Alfvénic modes are observed due to neutral beam injection for the first time in a reversed field pinch plasma. Modeling of the beam deposition and slowing down shows that the velocity and radial localization are high. This allows instability drive from inverse Landau damping of a bump-on-tail in the parallel distribution function or from free energy in the fast ion density gradient. Mode switching from a lower frequency toroidal mode number n=5 mode that scales with beam injection velocity to a higher frequency n=4 mode with Alfvénic scaling is observed.
authors.affiliation: Physics Department, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA. koliner@wisc.edu
authors.forename: J J
authors.initials: JJ
authors.lastname: Koliner
authors.forename: C B
authors.initials: CB
authors.lastname: Forest
authors.forename: J S
authors.initials: JS
authors.lastname: Sarff
authors.forename: J K
authors.initials: JK
authors.lastname: Anderson
authors.forename: D
authors.initials: D
authors.lastname: Liu
authors.forename: M D
authors.initials: MD
authors.lastname: Nornberg
authors.forename: J
authors.initials: J
authors.lastname: Waksman
authors.forename: L
authors.initials: L
authors.lastname: Lin
authors.forename: D L
authors.initials: DL
authors.lastname: Brower
authors.forename: W X
authors.initials: WX
authors.lastname: Ding
authors.forename: D A
authors.initials: DA
authors.lastname: Spong