In Chapter 2 it is shown that the effect of placing a sample exhibiting E.S.R. in the cavity of an E.S.R. spectrometer is to couple an effective spin-generator in series with the equivalent circuit of the cavity. For an unsaturable sample, the criterion of sensitivity for the cavity is that the available power from the spin-generator should be as high as possible for a given power dissipated in the cavity by the klystron. In this chapter the corresponding criterion for saturable samples is deduced. Both criteria are then expressed mathematically and considered in some detail for various types of sample. In particular, the effect of the frequency of operation and the limitations to sample size imposed by the inhomogeneity of the magnet are taken into consideration. The chapter includes a short account of the practical considerations of spectrometer cavity design, and concludes with a somewhat speculative consideration of the possible replacement of the cavity by a slow-wave structure.
KeywordsPermeability Quartz Microwave Torque Attenuation
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