Damping Rate Measurements of Medium n Alfv\'{e}n Eigenmodes in JET

POSTER

Abstract

Alfv\'{e}n Eigenmodes (AE's) with mode numbers 5 $<$ n $<$ 20 are expected to be unstable in burning tokamaks and may lead to loss of fast particle confinement. The active MHD spectroscopy program at JET has already provided a wealth of information about low n (n $\le $ 2) AE's in the past decade, but a recently installed array of four antennas is capable of driving higher mode numbered (n $<$ 100, 30 $<$ f $<$ 350 kHz) perturbations. In the latest JET campaign, the damping rates for several types of AE's were measured parasitically in a wide range of tokamak scenarios. We review the active MHD diagnostic and present the first measurements of medium-n AE stability on JET, then describe future plans for the active MHD spectroscopy project. The data analysis involves a novel method for resolving multiple AE's that exist at identical frequencies, which uses techniques based on the SparSpec code.

*This work is supported by US DOE Grant DEFG02-99ER54563.

Authors

  • Alexander Klein

    • MIT
  • Duccio Testa

    • CRPP, Association EURATOM-EPFL
  • J.A. Snipes

    • MIT PSFC
    • MIT
    • PSFC MIT
  • A. Fasoli

    • CRPP, Association EURATOM-EPFL
    • CRPP EPFL, 1015 Lausanne, Switzerland
  • Herv\&#039;e Carfantan

    • Laboratoire Astrophysique de Toulouse