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The formation of a nonlocal electron distribution function (EDF) in an argon dusty plasma of a dc glow discharge has been studied in a wide range of microparticle densities and their different spatial distributions inside a dusty cloud have also been explored. It is shown that the spatial profile of charges and the ambipolar potential can vary greatly, both with a change in the absolute values of the density of dust particles and the type of their spatial distribution. In turn, changes in the profiles of the ambipolar potential lead to strong differences in the nonlocal EDF at different points of the tube radius. This is most clearly seen at high densities of dust particles when nonmonotonic profiles of the potential distribution and reversal of the sign of the ambipolar field are formed. In this extreme case, great changes in the nonlocal EDF are observed not only at the discharge periphery but also inside the dust cloud. [ABSTRACT FROM AUTHOR]

In the present study, the machine learning algorithm is utilized for the first time to improve the probe diagnosis. Machine learning methods are utilized to improve the Langmuir probe diagnostic accuracy and the diagnosable plasma parameter range without changing the probe structure based on the Langmuir probe. They provide a new way for experimentally obtaining electron density. A DC glow discharge simulation model and experimental equipment are established. Utilizing the discharge pressure and voltage as independent variables, the simulation and experimental electron densities are collected, the simulation and experimental data are utilized for training, and the plasma electron density outside of the pressure and voltage range of the training data is predicted, thereby achieving the prediction. Simultaneously, when the data amount is large enough, even without experimental measurement, the electron density can be obtained directly through the input parameters, without relying on the plasma physical model. [ABSTRACT FROM AUTHOR]

The spatial distribution of dust particles in a low-pressure homogeneous positive column of a dc glow discharge in a right-angle curved (V-shaped) glass tube in different spatial orientations was observed and analyzed. It is found that in all cases, the ambipolar field prevents charged dust particles from falling on the wall of the glass tube. As a result, the design of the curved glass tube makes it possible to create in practice a simple and effective ambipolar trap and to implement the collection and control of dust particles in plasma. [ABSTRACT FROM AUTHOR]

Experiments were carried out in dusty plasmas of both the stratified and homogeneous positive columns (PCs) in a U-shaped discharge tube during its rotation from the vertical to the horizontal position. It is shown that in all cases the radial ambipolar field prevents charged dust particles from falling on the tube walls. For a vertically oriented tube, a dust cloud is observed only in a strong field of strata and is absent in a homogeneous plasma. In a horizontally oriented tube, the dust particles drift toward the anode in an axial external field. In this case, dust particles are trapped at the point of transition from the horizontal to the vertical section of the tube, in both the stratified and homogeneous PCs. It was concluded that for a V-shaped design of a cylindrical tube, an ambipolar dust trap, which is simple in technical execution, can be implemented, which makes it possible to hold dust particles in its lower part. [ABSTRACT FROM AUTHOR]