The diagnosis of surface wave plasmas via the interpretation of the surrounding electric fields.

One of the most commonly utilised methods of diagnosing surface wave plasmas in recent years has involved the measurement of the electric fields surrounding the plasma column. However, such work has almost exclusively been confined to plasmas with generating frequencies typically greater than 200 MHz. The research reported in this thesis represents the first systematic diagnostic investigation of low frequency surface wave plasmas. Three distinct diagnostic methods are employed which have been developed specifically to facilitate the diagnosis of low frequency surface wave plasmas. Each diagnostic technique is comprised of a two-stage process. The first stage involves the measurement of the electric fields surrounding the plasma, from which point determinations of the surface wave wave number are obtained. In the second stage, an axial plasma density gradient is inferred from the wave number values using a theoretical surface wave model. The thesis begins with a general introduction to the characteristics of surface wave plasmas and details the principle research objectives in the present investigation. Previous work in related areas is reviewed and its relevance to the present study highlighted. The equipment employed for the experimental part of the research programme is discussed in detail. The theoretical surface wave model is then developed which serves to interpret the experimental measurements. The design of the Axial and FRD diagnostic techniques is described together with their application for diagnosing the low frequency surface wave plasmas. A new diagnostic tool; the parasitic test-wave technique; has been developed and the results from which serve to validate the data from the Axial and FRD techniques. The thesis concludes with a summary of what has gone before and suggests topics for future research.