Biomedical subjects

Zoltan Sternovsky

Publications and source records attributed to Zoltan Sternovsky.

3 recordsLinked to original sources

PubMed2006

Method to find the electron distribution function from cylindrical probe data.

Druyvesteyn's method finds the distribution of electron speeds from the second derivative of probe data using the assumption that the distribution is spherically symmetric. For the disk probe, the data are more directly related to the velocity distribution projected onto the direction normal to the probe surface. The projected distribution is less sensitive to noise because it is related to the first derivative of the data rather than the second. For the cylindrical probe, the data are more directly related to the distribution of energies projected onto the plane perpendicular to the probe axis. A method is developed for recovering this projected distribution from digitized probe data. The method is mathematically more complex than Druyvesteyn's method, but has the advantage of being less sensitive to noise. The methods are compared using noise-free simulated data and using noisy data from a double-plasma device with multidipolar magnetic confinement.

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PubMed2005

Model for the density, temperature, and plasma potential of low-density hot-filament discharges.

A theoretical model is developed for the density and temperature of confined electrons and the plasma potential in low-density hot-filament discharges. These three parameters are found from a simultaneous solution of the equations for ion particle balance, electron particle balance, and electron energy balance. In the model, electrons are lost by diffusion in velocity over the potential barrier determined by the plasma potential. The confined electrons are heated by the unconfined electrons that are the secondaries from the wall and, to a lesser extent, by the primary electrons from the filaments. The plasma parameters calculated from the model agree with parameters measured in a double plasma device that has been modified to have a clean wall that gives a single value for the confining potential.

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PubMed2003

Monte Carlo model of ion mobility and diffusion for low and high electric fields.

A Monte Carlo method is described to model the mobility and diffusion of ions drifting in response to an electric field in a neutral gas. The model uses a collision frequency that is dependent upon the ion velocity and neutral gas thermal velocity. When implemented with a constant collision cross section for momentum transfer, the model gives a mobility that is constant for small electric fields (those giving a subsonic drift velocity) and that for larger fields falls inversely with the square root of the electric field. For argon ions drifting in argon, the model gives a close agreement with experimental data for the mobility for a wide range of electric fields when implemented with an energy-dependent cross section. For modeling of transverse diffusion, agreement with data is improved if the collisions are a combination of idealized charge-exchange collisions and hard-sphere collisions.

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