Drain Charge Research Articles

On charge nonconservation in FET's

It is shown that source and drain charges are not state variables in an FET, especially for source-drain voltages near zero. This behavior, observed in the model proposed in [2], is a genuine manifestation of the physics of FET's and is not a sign of improper behavior in a circuit simulator. However, if necessary, one may construct a model having these charges as state variables by introducing a current generator that transfers charge from source to drain internally without producing extra currents in the leads of the device.

Numerical study of cloud electrification in an axisymmetric, time‐dependent cloud model

An axisymmetric, time‐dependent, numerical cloud model has been applied to study how an isolated convective cloud can be electrified when rain and cloud particles are allowed to be charged by two particle charging mechanisms: ion attachment and polarization. Charge transports by electrical conduction, air convection, turbulent mixing, and the particle terminal velocities are all simulated. The close tie‐in of the electrical development with the evolutions of the cloud growth is one of the distinctive features of the study. The full dynamical‐microphysical‐electrical interactions are allowed in the simulation. The results of numerical experiments make it appear likely that the polarization charging mechanism is an important one for the electrification of warm clouds. The results also show that with the inclusion of the polarization charging mechanism and depending on the growth stage of the cloud the cloud can be electrified into various charge center structures, which have been observed and reported in the literature for many years. The numerical results show that the cloud cannot be rapidly electrified until rainwater forms and the polarization charging mechanism operates. Initially, the cloud is charged into a ‘positive dipole’ structure with a positive charge center in the upper part of the cloud and a negative one below. As the cloud grows further, another positive charge center forms below the main negative one. This weaker positive center is closely associated with the positively charged rain formed in that region. As the rain falls out of the cloud, this positive center extends below the cloud base. When the cloud top reaches its maximum level, the cloud base starts to rise and the cloud grows weaker thereafter. In the later stage of the development the charge distribution patterns of the rain field dominate the whole electrical structure of the model. The electrical pattern thereafter is greatly affected by the downward movement of the rain. With the fallout of the rain the cloud charge centers exhibit successfully a positive dipole structure and then a ‘negative dipole’ structure consisting of a negative charge center in the upper part of the cloud and a positive one below. The electrical force effects on the terminal velocities of the rain and cloud particles are also included in the study. The results show that the rain particle terminal velocities start to decrease by a few meters per second in a region where the electric field strength grows beyond 2 × 105 or 3 × 105 V/m. The cloud particle terminal velocities reach only several centimeters per second, even in the thunderstorm electrical state. As a result of the levitation effect on rain, the simulated cloud in the present study develops double maxima in the cloud water content, giving it a more irregular appearance than the weakly electrified or nonelectrified cloud.

Current-voltage characteristics of small size MOS transistors

One-dimensional analysis is used to find an upper and lower bound to the drain current of MOS transistors. The drain and source depletion regions and charge carrier velocity saturation are taken into account. These considerations are important in small devices.

INITIAL ELECTRIFICATION PROCESSES IN THUNDERSTORMS

Abstract Thunderstorm-electrification processes that develop in clouds which are everywhere above the freezing temperature have been analyzed. Nearly equal numbers of highly electrified positive and negative raindrops are formed by the association of large numbers of cloud droplets, and these themselves are statistically electrified by ionic diffusion. The observed charges carried by both cloud droplets and rain are therefore a manifestation of the ion pairs produced in the free atmosphere primarily by cosmic rays and radioactivity. The discharge characteristics of nearly equal numbers of oppositely electrified drops are determined for drops falling through an atmosphere wherein the positive and negative ionic conductivities are different. It is found that the differential discharge of highly charged rain falling in such an environment systematically separates positive and negative electricity and establishes a distribution that accounts quantitatively for thunderstorms of low to moderate intensity. Usefu...

RAINDROP CHARGE AND ELECTRIC FIELD IN ACTIVE THUNDERSTORMS

Abstract The electrical characteristics of two active spring thunderstorms are reported. Simultaneous surface measurements of the sign and magnitude of the free charge on individual raindrops, the electric field and precipitation rate have been made. More than 7000 drops, representing a continuous sample of the drops falling in the storms, show no important systematic dependence on the sign or magnitude of the instantaneous electric field. The measurements show that the convected current to the earth frequently exceeds the conduction currents by a large factor, and, therefore, the charged rain may determine the electric field at the surface. The average measured free charge brought down by positively charged rain was 0.022 esu per drop, and by negatively charged rain was 0.031 esu per drop. The ratio of the negative free charge to the positive free charge brought down by rain was 1.2, while the ratio of the number of negative drops to the number of positive drops was 0.88.

Results of the dutch cosmic-ray expedition 1933: Briefly communicated

A new method for the mechanical recording of cosmic radiation was inaugurated. The method was independent of the vibration and rolling of the steamer, and especially adapted for measuring the ionisation in deep water. The latitude effect of the earth's magnetism on the intensity of cosmic radiation was measured along three different routes with four different instruments. The differences of intensity found may be explained by Störmer's theory. The penetrating power of the radiation decreases with magnetic latitude, as measured in water, lead and iron, and in air with an airplane to 5000 meters. Intensity measurements were carried out for two positions down to 270 meters under water. At 270 meter the ionisation was 1 300 of its value at the surface. Near the equator measurements were performed with two registering electrometers attached to balloons to an altitude of 15 kilometers. The values found are much smaller than those for the same altitude at higher magnetic latitudes. Registration in the tropics gives the result that electrically charged rain clouds may cause considerable disturbances. If these are absent, the variation certainly is below 0.5%. With a set of 4 Geiger counters, measurements of 4-fold coincidences were performed in different directions, during 8 weeks without interruption. These measurements prove the existence of positive and of negative corpuscles, giving maxima West and East, whereas there is very little difference North and South. The number of primary corpuscles incident at the equator in a vertical direction is not appreciably diminished by 36 cm of lead. All the observed effects give fairly conclusive evidence for electrically charged primaries under the influence of the earth's magnetic field.

The influence of rain on the atmospheric‐electric field

Photographic records of the atmospheric‐electric field variations at times of rain are examined along with pluviograms covering these periods. It is found that the normal effect of rain is to abruptly reverse the normal positive field in the early stages, while in a few cases it results in a sudden reduction without change of sign. This abrupt change disappears speedily when the disturbing shower is of short duration. An analysis of the results of G. C. Simpson at Simla (1908–1909) in regard to the charge brought down by rain is given. It is shown that in the earliest stages of charged rain, in more than 85 per cent of the cases, the net charge brought down by rain is positive. It is then shown that the effect of rain on the field is due to the transfer of charge by the rain from the upper air. Calculation shows that the charge transferred by the rain is of the order necessary to produce the observed changes of potential. The explanation covers the cases of heavy rain attended with frequent reversals and very high values of the field.

Societies and Academies

Societies and Academies