No abstract

In this communication the effect of ion temperature on the propagation of electron‐ion whistlers in the ionosphere is investigated. A general expression including the effect of ion temperature is derived for the group travel time for the electron‐ion whistler as it travels from the base of the ionosphere to the satellite. A study of the dependence of the group travel time on ion temperature indicates that thermal effects contribute about 20% to the total group travel time for the proton whistlers. Further, from the expression for the group travel time including the effect of the ion temperature in conjunction with the generalized dispersion relation a relation for the cyclotron damping rate (both temporal and spatial) has been obtained. A detailed study of the cyclotron damping rate with travel time and ion temperature leads to the conclusion that the observed amplitude cutoff characteristics for the proton whistler can be explained on the basis of the mechanism of cyclotron damping. It is also shown that the knowledge of the group travel time of an electron‐ion whistler can be used to estimate the ion temperature at the satellite.

Proton transport in ammonium para-tungstate pentahydrate (NH4)10WIZ041 .5H20 (APT.SH,O) has been established using coulometry, transient ionic current, IR and electrical conductivity measurements along with the TGA/DTA results of Kiss and co-workers. The mobile ions are NH;, H' and 02-. The ions (H' and 02-) are the productsof electrolysisof the inter-layerwater. The temperaturedependence ofthe electrical conductivity has been correlated with the accompanying dehydration and de-ammoniation reaction of A P T -~H ~O .

In this communication a theoretical relation is derived for the group travel time of the proton whistlers to reach the satellite from their place of occurrence. The expression for the group travel time contains two terms. The first term is the dominant term and is inversely proportional to (Ω ‐ ω)1/2, where Ω and ω are the proton gyrofrequency and the wave frequency, respectively. The contribution from the second term, which is inversely proportional to (Ω ‐ ω)7/2, is about 10% of the first term. It is shown that the group travel time is sensitive to the variation of temperature, gradient of proton gyrofrequency, and ion density along the path of a proton whistler. The effect of variation in each of the above parameters on the group travel time is discussed, and it is shown that an estimate of proton temperature can be made from the measured data on the proton whistlers.

The age of radioactive mineralization (Singhbhum district, Bhalki, India) has been determined on the basis of thermoluminescence of smoky quartz crystals collected from nonradioactive intrusive layers adjacent to radioactive veins. The 'age equation' has been derived by considering the absorption coefficient and the average energy of -• rays reaching the quartz crystals. The total dosage received by smoky quartz crystals under field conditions has been computed from an experimental calibration curve of dosage versus thermoluminescence intensity. The value of age thus obtained is 940 _ 160 m.y., which is in fair agreement with the values estimated from geological evidence. 1275 1276 KAUL, BItATTACItARYA, AND TOLPADI