FEASIBILITY OF ALPHA PARTICLE DIAGNOSIS BY COLLECTIVE MICROWAVE SCATTERING IN TOKAMAK FUSION EXPERIMENTS
A review of the physical principles behind the proposed scattering diagnostic for alpha particles is presented. Quantitative expressions are given for the ratio of the alpha-scattered power to the electron- scattered power and background power. The anticipated best-case signal to noise, ignoring coherent pick-up, is given. Magnetic field effects can give rise to enhancement of the scattered power due to lower hybrid waves. However the enhancement is small unless the value of the scattering parameter alpha is large (geq 4) and in any case will lead to a result which is exceptionally hard to interpret as a diagnostic of the alphas. The resonant enhancement is therefore probably better avoided. Discussion of the likely electron cyclotron emission background is given, since it will probably be the dominant noise signal. The achievable signal to noise in JET appears to be in the range one to 100, depending on the assumed parameters. Geometrical choices for optimising the signal to noise are briefly discussed.
Bibliographic Reference: REPORT JET-R(87)07, 1987, AVAILABILITY: JET, ABINGDON, UK
Record Number: 1989126081300 / Last updated on: 1989-05-01
Available languages: en