Radioactive Charge Research Articles

Charge injection into the atmosphere by explosive volcanic eruptions through triboelectrification and fragmentation charging

Volcanic eruptions are associated with a wide range of electrostatic effects. Increasing evidence suggests that high-altitude discharges (lightning) in maturing plumes are driven by electrification processes that require the formation of ice (analogous to processes underpinning meteorological thunderstorms). However, electrical discharges are also common at or near the volcanic vent. A number of “ice-free” electrification mechanisms have been proposed to account for this activity: fractocharging, triboelectric charging, radioactive charging, and charging through induction. Yet, the degree to which each mechanism contributes to a jet's total electrification and how electrification in the gas-thrust region influences electrostatic processes aloft remains poorly constrained. Here, we use a shock-tube to simulate overpressured volcanic jets capable of producing spark discharges in the absence of ice. These discharges may be representative of the continual radio frequency (CRF) emissions observed at a number of eruptions. Using a suite of electrostatic sensors, we demonstrate the presence of size-dependent bipolar charging (SDBC) in a discharge-bearing flow for the first time. SDBC has been readily associated with triboelectric charging in other contexts and provides direct evidence that contact and frictional electrification play significant roles in electrostatic processes in the vent and near-vent regions of an eruption. Additionally, we find that particles leaving the region where discharges occur remain moderately electrified. This degree of electrification may be sufficient to drive near-vent lightning higher in the column. Thus, near-vent discharges may be underpinned by the same electrification mechanisms driving CRF, albeit involving greater degrees of charge separation.

A Three-electrode gas arrester for low voltage isolation coordination

This work aims is to design, fabricate and test a gas surge arrester with optimum characteristics based on testing the influence of all parameters that affect the characteristics of gas surge arresters for the coordination of low voltage isolation. After extensive research on the surge arrester model and reviewing all available literature, a three-electrode prototype surge arrester was made. The prototype gas used was a mixture of 0.8 He + 0.2 SF6 and the working point was set to the right of Pashen’s minimum. Examination of thus constructed prototype and three commercial surge arresters of the same nominal voltage has shown that the surge arrester model was better in every respect. It should be noted that using the developed model, gas arresters with radioactive charging can be discarded, which is important for environmental reasons. The obtained results are very important in power engineering since the operation and control of the operation of power circuits, which are the source of overvoltage which are performed by electronic circuits.

Synthesis of Ceramic and Glass Ceramic Matrices with Immobilized Cesium Radionuclides for Active Zones of Ionizing Radiation Sources

The present study was devoted to the development of alternative solutions related to replacement of highly dispersed powder of cesium chloride (137CsCl) used as a filler of active zones of g-radiation IRSs (ionizing radiation sources of the closed type) by safer and more efficient in operation highly compacted ceramic or glass ceramic material. An advanced method of fabrication of highly compacted (density of ~99.8 % of the theoretical one) aluminosilicate (artificial NaA zeolites) ceramic and glass ceramic matrices characterized with high construction strength (compression strength ~149 MPa) applicable for reliable immobilization of cesium radionuclides (leaching rate <10-5–10-6g/cm2×day) has been suggested. Unique matrices properties are ensured by advanced features of the technology of Spark Plasma Sintering (SPS) based on high-rate electro-pulse consolidation of the radioactive charge (adsorbed cesium content ~22.16 mass %) into thermodynamically stable ceramics or glass ceramics. The earlier unstudied features of the SPS consolidation of natural zeolite powders sorption-saturated with a radioactive cesium simulant are presented, including the dynamics of their compaction and specifics of phase and structural transformations under effect of irreversible spark plasma conditions.

Studying the impact of radioactive charging on the microphysical evolution and transport of radioactive aerosols with the TOMAS-RC v1 framework

Radioactive charging can significantly impact the way radioactive aerosols behave, and as a result their lifetime, but such effects are neglected in predictive model studies of radioactive plumes. The objective of this work is to determine the influence of radioactive charging on the vertical transport of radioactive aerosols in the atmosphere, through its effect on coagulation and deposition, as well as quantifying the impact of this charging on aerosol lifetime. The TwO-Moment Aerosol Sectional (TOMAS) microphysical model was extended to account for radioactive charging effects on coagulation in a computationally efficient way. The expanded model, TOMAS-RC (TOMAS with Radioactive Charging effects), was then used to simulate the microphysical evolution and deposition of radioactive aerosol (containing the isotopes 131I and 137Cs) in a number of idealized atmospheric transport experiments. Results indicate that radioactive charging can facilitate or suppress coagulation of radioactive aerosols, thus influencing the deposition patterns and total amount of radioactive aerosol mass available for long-range transport. Sensitivity simulations to uncertain parameters affirm the potential importance of radioactive charging effects. An important finding is that charging of neutral, coarse mode aerosol from background radiation can reduce coagulation rates and extend its lifetime in the atmosphere by up to a factor of 2.

Potentials of the ECR 1+ n+ charge breeding for radioactive ions

During the past three years, a Phoenix ECR charge breeder has been tested on-line with various beams delivered by the ISOLDE facility. The performances obtained so far are compatible with most of the requirements for future production of intense radioactive charge bred beams. However, there are aspects that are could be improved. These concern beam purity, injection efficiency and the capability of raising high charge state in continuous or pulsed mode. We summarize here the results obtained with the present Phoenix ECR charge breeder and a few simple upgrades that are foreseen to improve its performances.

Boundary conditions and growth of mean charges for radioactive aerosol particles near absorbing surfaces

Particle charge evolution equation is considered in the presence of diffusion and drifts combined with bipolar and radioactive charging in the vicinity of absorbing surfaces (walls). Boundary conditions to be prescribed for solving the mean charge evolution equation have been derived. It is shown that the mean charge J( x) at a distance x from the surface ( x=0) satisfies the boundary condition ∂J ∂x x=0= U(0) 2D(0) [αJ(0)+σ 0 2], where U( x) and D( x) are the drift velocity and diffusion coefficients respectively, α=1 (0) for radioactive (non-radioactive) aerosols, and σ 0 2 is the variance of the Boltzmann charge distribution. Using this, specific cases of charge build-up of radioactive particles undergoing turbulent diffusion near walls is examined. Radioactive particle charges are found to increase both for zero and negative electric fields, although the increases are far smaller than those expected from stationary-state formulae. The results are further discussed.

Statistics of aerosol electric charging

The paper discusses a theoretical approach to the statistics of aerosol electric charging. It is based on the analysis of electric charge flows among charged aerosols. The steady-state aerosol charge distribution is described theoretically for normal environments, also for radioactive charging, charging by external irradiation and charging in external electric fields. Theoretical results are compared with experimental data taken from the literature (including early work by the authors (Emets et al., J. Aerosol Sci. 22, 389–394 (1991)). The agreement is good.

28 O 01 A method for estimating radioactive aerosol charge with spatially inhomogeneous ion concentrations

28 O 01 A method for estimating radioactive aerosol charge with spatially inhomogeneous ion concentrations

Electrically stimulated aerosol filtration in packed beds

AbstractSince charged particles are quite mobile in an electric field, charge is often added to aerosol particles to facilitate capture; indeed, provision for such charging is an indispensable part of electrostatic precipitators. Nevertheless, calculations disclose that a very slight amount of charge may suffice when the distance the aerosol particle must travel to the collector surface is small, contrary to the usual situation. In the experiments described, here, a model aerosol containing 0.5 μm polystyrene particles passed through a radioactive charge neutralizer to deliberately reduce the charge as much as practicable and then through a packed bed under the influence of a fairly large external electric field. Filtration efficiencies approaching 100% were obtained owing to the influence of the field on small amounts of residual charge.

Kinetics of the change in the radiation charge in dielectrics

1. A model of conduction of charges, formed on the surface of a dielectric during radioactive decay, was proposed. 2. An equation was derived, describing the kinetics of the change in the radiation charge. 3. The conditions of applicability of the dynamic condenser method to the investigation of the behavior of a radioactive charge were determined. 4. The dependence of the stationary radiation charge density on the temperature was investigated. 5. The equations obtained were compared with the experimental data.

A spinner magnetometer

A commercially made lock-in amplifier and low-noise, high-gain preamplifier have been used in designing and constructing a spinner magnetometer for measuring the remanent magnetization of small rock specimens. The novel design features of the pickup coil transducer include the use of a compensated dual-coil array, aluminum eddy-current shielding, and radioactive electrostatic charge eliminators. The instrument detects specimen moments greater than 4 × 10−7 emu. This sensitivity corresponds to an intensity of magnetization of 4 × 10−8 emu/cm³ for the largest specimens accommodated (10 cm³). The error of direction and intensity measurement is less than 1° and 2%, respectively, for specimens with intensities greater than 2 × 10−7 emu/cm³.

Radioactive Charging Effects with a Dielectric Medium

A process is described in which radioactive radiation traverses a solid dielectric medium to charge a collector electrode. This process offers a simple method of studying effects of radiation on matter such as bombardment-induced conductivity, secondary emission, charge soakage, and radiation absorption. Typical data are given. Possible application of this process for the construction of a current or voltage source for use in electronic devices is discussed.