On steady-state distribution of aerosolparticle electric charges

Poluéktov, P. P.; Emets, E.P.; Kascheev, V.A.; Bochvar, A. A.

doi:10.1016/s0021-8502(05)80079-5

Cited by 10 publications

(1 citation statement)

References 3 publications

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“…[9a], one obtains the velocity-averaged charge distribution as [10] which is the "Boltzmann law" of charge distribution, well known as the continuum approximation to a more generalized, discrete distribution (17,18). Thus, while the charge distribution is not affected by the coupling term in Eq.…”

Section: Stationary Form Of the Charge-velocity Distribution Functionmentioning

confidence: 99%

Kinetic Derivation of the Electromigration Equation for Aerosol Particles in the Presence of Bipolar Charging

Mayya

Sapra

2002

Journal of Colloid and Interface Science

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Section: Stationary Form Of the Charge-velocity Distribution Functionmentioning

confidence: 99%

Kinetic Derivation of the Electromigration Equation for Aerosol Particles in the Presence of Bipolar Charging

Mayya

Sapra

2002

Journal of Colloid and Interface Science

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Electric charging of aerosol particles taking into account track fluctuations of the ion density

Kashcheev¹,

Mikhalkova²,

Poluéktov³

1994

At Energy

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Aerosols can acquire a significant electric charge when the atmosphere is ionized (or particles are ionized) by irradiation, heating, chemical reactions, and so on. Charging of aerosols in an ionized atmosphere (even under the conditions of a spatially uniform ion distribution) is of a statistical character [1][2][3], and the statistics are determined from the dynamic equilibrium of a charged particle and the embedded gas.Under the conditions of irradiation additional factors resulting in a statistical spread of the charges of the particles appear: emission of charge by an active particle during radioactive decay and fluctuations of the ion concentration in the tracks of ionizing radiation which appear in the gas. The nonuniformity of the distribution of the radioactive matter over the particles (even for the same particle size) that is associated with the genesis of particles can play a definite role. The contribution of this factor to the statistical distribution of the charges can be easily taken into account.Pronounced tracks with large changes in the ion density are formed in the normal atmosphere during the passage of s-particles and fission fragments; for B-electrons such fluctuations are smaller. An aerodispersed system can be found in conditions of external irradiation when the particles may be inactive or self-irradiated, when some particles are radioactive or the embedded gas is radioactive. We confine our attention to the case of inactive particles in an irradiation field with a uniform dose rate (i.e., the case of radiation fluxes which are equal at all points in space). This means that the track concentration (after averaging over a corresponding time interval) is the same for all points in the gas.*The tracks are statistical objects, which have a different size and ion distribution. Fluctuations of the density of ions having charges of opposite sign are different at different points of the track, and for this reason in the general case they are independent random quantities. The spatial correlations of the ion density fluctuations are not of interest, since we are concerned with the charging of separate particles which are small compared to the cross sections of the tracks. The objective of this work is to calculate the effect of fluctuations of the ion density in tracks on the statistics of charging of aerosols.The introduction of the distribution function f~P(R, k) of the transformation of the charge accompanying capture in the track of an aerosol particle of size R and charge k. i.e.. the probability that a particle with an initial charge k acquires a charge (k + p) when it is captured in a track (this probability being averaged over the volume of the track), is fundamental for the further description. For each R the function ,.OP(R, k) is different from zero only for the bounded number p [-Po. Po], and P0 increases with R. Evidently, flP(R, k) depends on the type of radiation producing the track. For example. for R = 1 /zm for tracks of B-particles P0 = 1 and for tracks of s-particles P0 = 10. ...

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Statistics of charging ofβ-active aerosols

Kashcheev¹,

Mikhalkova²,

Poluéktov³

1994

At Energy

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Electric charging of particles is a characteristic process occurring in aerodispersed systems under both external radioactive irradiation self-irradiation. Intensive investigations of this process started only in the 1970s-1980s. We call attention first to the works [1][2][3][4][5][6][7], which were concerned primarily with the investigation of the charging of hot particles. These works established that radioactive aerosols are unipolarly (positively) charged due to secondary-electron emission accompanying tx and/3-decay on particles. Thus one or two electrons emerge from a 1-/.tm in diameter particle in a single /~ decay and up to 40 secondary electrons are emitted in a single ot decay. Charging of radioactive aerosols is now under intensive study in the USA, Germany, Great Britain, and Japan. The most important theoretical results were obtained in [6], where the system of kinetic equations governing the charging for low particle activities were solved by means of computer modeling and the results agreed with the experimental data.It is significant that charging of aerosols leads not only to interaction of the particles with the electric field and a change in the efficiency of precipitation or particle confinement but also to higher diffusion mobility [8]. Obviously, that a knowledge of the characteristics of aerosol charging is important not only for determining aerosol precipitation on different surfaces but also for more efficient operation of the equipment used for purification of radioactive fluxes, in application, in particular, to accidents at nuclear power plants.Our objective in the present paper is to derive analytic formulas for the distribution of electric charge over/3-active particles in a bipolar atmosphere. Before proceeding to the calculation, we give a brief exposition of the extension of the method of detailed balance to stationary aerosol-charging processes.Method for Calculating the Distribution of Charge over Particles. Consider a quite rarefied aerodispersed system, in which collisions of aerosol particles (and the corresponding charge exchange) can be neglected. The charge on the aerosol particles can change as a result of absorption of electrons or ions from the atmosphere as well as the emission of charged particles. One particle can affect another only indirectly, through the general ionic atmosphere, and for this reason the distributions of charge over particles in different size fractions are independent of one another. Let the system contain N particles with radius R. Let nk(t) be the number of particles which at time t have electric charge ek, k = 0, +_ 1, +~ _+2 ..... where e is the elementary electric charge. At any time t the relation ,=~nk(t) = N, which follows from particle number conservation, must be satisfied. If we now introduce the probability wkJ of a change in the charge state of a particle per unit time, where ke is the particle charge before the change and je is the change in the charge as a result of a single charge exchange act, then the general form of the kinetic ...

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On steady-state distribution of aerosolparticle electric charges

Cited by 10 publications

References 3 publications

Kinetic Derivation of the Electromigration Equation for Aerosol Particles in the Presence of Bipolar Charging

Kinetic Derivation of the Electromigration Equation for Aerosol Particles in the Presence of Bipolar Charging

Electric charging of aerosol particles taking into account track fluctuations of the ion density

Statistics of charging ofβ-active aerosols

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