Speaker
Kevin Ronald
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P2.4011.pdf
Apparatus for investigating non-linear microwave interactions in
magnetised plasma
K. Ronald1, A.D.R. Phelps1, R.A. Cairns2,1, R. Bingham3,1, B Eliasson1, M.E. Koepke4,1,
A.W. Cross1, D.C. Speirs1, C.W. Robertson1, and C.G. Whyte1
1
Department of Physics, SUPA, University of Strathclyde, Glasgow, G4 0NG, Scotland, UK
2
School of Mathematics and Statistics, University of St Andrews, KY16 9SS, Scotland
3
STFC Rutherford Appleton Laboratory, Harwell, Oxford, Didcot, OX11 0QX, England
4
Department of Physics, West Virginia University, Morgantown, WV 26506-6315, USA
Electromagnetic wave injection plays a dominant role in the introduction of energy in laser
plasma interactions and in the heating of magnetically confined fusion reactors. Nonlinear
coupling enables energy to be transferred between one or more EM waves interacting in
plasma. Coupling of injected EM waves to Langmuir and ion acoustic waves is of interest for
a number of laser plasma interactions and in ionospheric physics experiments. Long (and
short) pulse signals with normalised intensities approaching those used in some recent laser
plasma interactions can be generated using flexible microwave amplifiers. Multi-wave
microwave interactions can be directly relevant to the delivery of heating and current drive in
future magnetic confinement fusion (MCF) reactors coupling to cyclotron motion of ions and
electrons and to lower hybrid waves. Understanding of the nonlinear electrodynamics will
benefit from employing microwave sources and amplifiers to precisely launch and
electronically control multiple EM signals. The relatively long lived, benign and accessible
plasma relevant to coupling of microwave frequency signals will enable the use of insertion
diagnostics in addition to analysing the EM signals.
A linear plasma experiment is being designed, which will be magnetised at up to 0.8T. The
plasma will be created by an RF helicon source, using a whistler wave injected from a
high-field region to generate a dense, large, cool plasma with high ionisation fraction (an
electron number density up to 1019m-3 has been reported in other helicon experiments). A
range of frequency-flexible microwave sources will provide beams to enable multi-wave
coupling experiments. The paper will present the proposed apparatus and will outline the
envisioned research programme.
The authors gratefully acknowledge support from the EPSRC, MBDA UK Ltd and TMD
Technologies Ltd.
