An experimental determination of the effect of ion size on diffusion has been made by measuring the diffusivity of Rb 86 in NaCl, KC1, and RbCl. In the temperature region near the melting point the results follow the Arrhenius relation D = D Q exp(-E/kT). The Arrhenius parameters are Z) 0 = 205±47,26.8±8.7, 33.3±7.1 cm 2 /sec and Е = 2.11±0.02, 2.04±0.03, 1.99±0.02 eV for NaCl, KC1, and RbCl host crystals, re spectively. We conclude that the effect of ion size is important with regard to both the frequency factor and activation energy. The results are in general agreement with the theory proposed in the previous paper.
Resistive m=1 modes associated with minidisruptions of current carrying plasmas are shown to be strongly influenced simultaneously by the effects of finite ion gyroradius, finite drift wave frequency, and ion-ion collisions in the plasma regimes of interest. The modes acquire finite frequency of oscillation and, for low β, the reduction in their growth rates is due mainly to the drift wave frequency, the effect of ion-ion collisions being slight (less than 10% effect); but, even for low β, ion-ion collisions significantly alter the radial structure of the modes. As a result, the reconnecting mode, which tends to lose its radial localization above a threshold temperature, remains well-localized when ion-ion collisions are included.
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