Tunable microwave TM010 mode cavity of simple construction with improved performance for gas breakdown and materials investigation

The paper describes the construction of a tunable microwave (2.45 GHz) TM010 mode cylindrical cavity which has improved features in the measurement of gas discharge phenomena and properties of materials. Theoretical work, supported by experiment, demonstrates that during controlled end-wall deformation tuning ranges of at least ¿¿ 40 MHz are achieved, for which there is negligible change in the electric field at the cavity axis. An additional feature is that a linear law relates the deformation depth to the resulting frequency change, over the useful tuning range. The cavity can be fabricated simply, and with relaxed tolerances. Accurately made tuning stubs are not required, and their absence ensures a gas-tight structure.