Tritiated Dust Levitation by Beta-Induced Static Charge

Sheaths , Double Layers and Dust Levitation

This paper contains an overview of certain sheath phenomena, namely the criterion for sheath formation, some examples of double layers and a description of some recent experiments on the suspension ofdust particles in a sheath. A detailed review is not attempted and results obtained at Oxford are used to illustrate the last two topics.

Factors Affecting the Inhalation Dose from Tritiated Dust and Flakes . Factors Affecting the Inhalation Dose from Tritiated Dust and Flakes

Experimental levitation of dust grains in a plasma sheath

[1] Dust grains have been observed to levitate above the surface of the Moon and as spokes in Saturn’s rings. In order to gain a better understanding of these observations, we have performed levitation experiments on dust grains in a low-density plasma. Plasma sheath potential profiles, measured by an emissive probe, are used to determine the spatial dependence of the electric force on a grain ...

Dust grain charging and levitation in a weakly collisional sheath

An experiment is described in which monodisperse dust grains are levitated within a dc sheath above a conducting plate in argon plasma. For plate bias voltages that are not too negative ~>210 electron temperatures!, the observed dust levitation heights are near to values calculated from a model combining equations for the sheath with those for grain charging. When the plate is more negatively b...

Chromosome Pulverization in Micronuclei Induced by Tritiated Thymidine

Cultures of a pseudodiploid cell line (Don) of Chinese hamster origin were exposed to varying doses of tritiated thymidine (TdR-(3)H) for relatively long periods of time. In addition to previously observed chromosomal aberrations) such as breaks and reunions, a substantial number of interphasic cells with micronuclei and of metaphases associated with pulverized chromosomes was found; both pheno...