scholarly journals Self-oscillations of non-neutral plasma diode

2020 ◽  
Vol 1 (1) ◽  
pp. 54-62
Author(s):  
Dmitry Levko
Keyword(s):  
Mean Free Path ◽  
Plasma Potential ◽  
The Self ◽  
Emission Current ◽  
Cathode Voltage ◽  
Particle In Cell ◽  
Plasma Diode ◽  
Neutral Plasma ◽  
Background Gas ◽  
Electron Mean Free Path

Self-oscillations of non-neutral plasma diode operating in the anode-glow mode are analysed using the self-consistent one-dimensional Particle-in-Cell Monte Carlo collisions model. In order to obtain these states, the current exceeding the space-charge limited current has to be emitted from the cathode, the electron mean free path must be much longer than the cathode-anode gap, and the cathode voltage must be slightly larger than the ionization potential of the background gas. It is obtained that in such a case, immobile ions form the electrostatic trap for the electrons generated in the cathode-anode gap. These electrons oscillate between the cathode and the anode causing the self-oscillations of the plasma potential. It is shown that the increase of the emission current leads to the increase of the frequency of the obtained self-oscillations. Starting at some value of the emission current, a lot of the emitted electrons are got trapped in the electrostatic well, which leads to the transition to chaos.

scholarly journals Phonon residual resistance of pure crystals

2015 ◽  
Vol 29 (29) ◽  
pp. 1550206
Author(s):  
A. I. Agafonov
Keyword(s):  
Electric Field ◽  
Constant Electric Field ◽  
Finite Thickness ◽  
Mean Free Path ◽  
Residual Resistivity ◽  
Boltzmann Transport ◽  
Residual Resistance ◽  
Temperature Resistance ◽  
Electron Mean Free Path ◽  
The Ideal

In this paper, using the Boltzmann transport equation, we study the zero temperature resistance of perfect metallic crystals of a finite thickness d along which a weak constant electric field E is applied. This resistance, hereinafter referred to as the phonon residual resistance, is caused by the inelastic scattering of electrons heated by the electric field, with emission of long-wave acoustic phonons and is proportional to [Formula: see text]. Consideration is carried out for Cu, Ag and Au perfect crystals with the thickness of about 1 cm, in the fields of the order of 1 mV/cm. Following the Matthiessen rule, the resistance of the pure crystals, the thicknesses of which are much larger than the electron mean free path is represented as the sum of both the impurity and phonon residual resistances. The condition on the thickness and field is found at which the low-temperature resistance of pure crystals does not depend on their purity and is determined by the phonon residual resistivity of the ideal crystals. The calculations are performed for Cu with a purity of at least 99.9999%.

scholarly journals Hydrodynamic Hamilton theory for discussing the space charge (Langmuir–Child Law) at high density particle currents between poles

1988 ◽  
Vol 6 (3) ◽  
pp. 579-586 ◽  
Author(s):  
Cord Passow
Keyword(s):  
Space Charge ◽  
Charge Carriers ◽  
The Self ◽  
Density Functions ◽  
Space Charge Limited Current ◽  
Stationary Plasma ◽  
Self Consistent ◽  
Solution Methods ◽  
Background Gas ◽  
Systematic Derivation

In order to calculate more generally the space-charge limited current between two points of different voltage, modern differential geometrical methods are applied. This problem was first treated by Child (1911) and later by Langmuir (1913). It is possible, for example, to account for effects due to more than one charge component as well as the influence of a neutral background gas (which causes ionization and scattering of charge carriers). A systematic derivation of the self-consistent representation based on a Hamilton theory for density functions is given, and solution methods are discussed. The concept is designed to investigate ion and electron diodes with very intense currents, but it may also be useful for treating space charge problems in a stationary plasma.

Interplay Between Thermoelectric and Thermionic Effects in Heterostructures

2000 ◽  
Author(s):  
Taofang Zeng ◽  
Gang Chen
Keyword(s):  
Film Thickness ◽  
Free Path ◽  
Thermionic Emission ◽  
Approximate Solutions ◽  
Mean Free Path ◽  
Boltzmann Transport ◽  
Thermoelectric Effects ◽  
Double Heterojunction ◽  
The Mean ◽  
Electron Mean Free Path

Abstract When electrons sweep through a double-heterojunction structure, there exist thermionic effects at the junctions and thermoelectric effects in the film. While both thermoelectric and thermionic effects have been studied for refrigeration and power generation applications separately, their interplay in heterostructures is not understood. This paper establishes a unified model including both thermionic and thermoelectric processes based on the Boltzmann transport equation for electrons, and the nonequilibrium interaction between electrons and phonons. Approximate solutions are obtained, leading to the electron temperature and Fermi level distributions inside heterostructures and discontinuities at the interfaces as a consequence of the highly nonequilibrium transport when the film thickness is much smaller than the electron mean free path. It is found that when the film thickness is smaller than the mean free path of electrons, the transport of electrons is controlled by thermionic emission. The coexistence of thermoelectric and thermionic effects may increase the power factor when the electron mean free path is comparable to the film thickness.

scholarly journals Control of Mooij correlations at the nanoscale in the disordered metallic Ta–nanoisland FeNi multilayers

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
N. N. Kovaleva ◽  
F. V. Kusmartsev ◽  
A. B. Mekhiya ◽  
I. N. Trunkin ◽  
D. Chvostova ◽  
...  
Keyword(s):  
Magnetic Moments ◽  
Mean Free Path ◽  
Dc Conductivity ◽  
Electronic Excitations ◽  
Many Body ◽  
Multilayered Structures ◽  
Multilayered Films ◽  
Disordered Metals ◽  
Electron Mean Free Path ◽  
Shed Light

AbstractLocalisation phenomena in highly disordered metals close to the extreme conditions determined by the Mott-Ioffe-Regel (MIR) limit when the electron mean free path is approximately equal to the interatomic distance is a challenging problem. Here, to shed light on these localisation phenomena, we studied the dc transport and optical conductivity properties of nanoscaled multilayered films composed of disordered metallic Ta and magnetic FeNi nanoisland layers, where ferromagnetic FeNi nanoislands have giant magnetic moments of 10$$^3$$ 3 –10$$^5$$ 5 Bohr magnetons ($$\mu _{\mathrm{B}}$$ μ B ). In these multilayered structures, FeNi nanoisland giant magnetic moments are interacting due to the indirect exchange forces acting via the Ta electron subsystem. We discovered that the localisation phenomena in the disordered Ta layer lead to a decrease in the Drude contribution of free charge carriers and the appearance of the low-energy electronic excitations in the 1–2 eV spectral range characteristic of electronic correlations, which may accompany the formation of electronic inhomogeneities. From the consistent results of the dc transport and optical studies we found that with an increase in the FeNi layer thickness across the percolation threshold evolution from the superferromagnetic to ferromagnetic behaviour within the FeNi layer leads to the delocalisation of Ta electrons from the associated localised electronic states. On the contrary, we discovered that when the FeNi layer is discontinuous and represented by randomly distributed superparamagnetic FeNi nanoislands, the Ta layer normalized dc conductivity falls down below the MIR limit by about 60%. The discovered effect leading to the dc conductivity fall below the MIR limit can be associated with non-ergodicity and purely quantum (many-body) localisation phenomena, which need to be challenged further.

Non-neutral plasma diode in the presence of a transverse magnetic field

2016 ◽  
Vol 23 (6) ◽  
pp. 062118 ◽  
Author(s):  
Sourav Pramanik ◽  
V. I. Kuznetsov ◽  
A. B. Gerasimenko ◽  
Nikhil Chakrabarti
Keyword(s):  
Magnetic Field ◽  
Transverse Magnetic Field ◽  
Transverse Magnetic ◽  
Plasma Diode ◽  
Neutral Plasma

scholarly journals Particle Simulation Model for Self-Field Magnetoplasmadynamic Thruster

Energies ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1579
Author(s):  
Li ◽  
Zhang ◽  
Wu ◽  
Cheng ◽  
Du
Keyword(s):  
Electric Field ◽  
The Self ◽  
Particle Simulation ◽  
Shielding Effect ◽  
Induced Magnetic Field ◽  
Plasma Region ◽  
Cathode Sheath ◽  
Particle In Cell ◽  
Plasma Distribution ◽  
Bulk Plasma

In order to clarify the discharge principle of the self-field magnetoplasmadynamic thruster (MPDT), a two-dimensional axisymmetric particle-in-cell/Monte Carlo collision (PIC/MCC) model is proposed. The spatial distribution and the collision characteristics of discharge plasma were calculated using this model. In addition, the influence of the operation parameters on the plasma was analyzed including the voltage and mass flow rate. The effectiveness of the model was verified by comparison to the experimentally induced magnetic field. It was found that the electrons were mainly accelerated by the electric field in the cathode sheath and the electric field shielding effect of plasma was obvious in the bulk plasma region. Due to the pinch effect, the charged particles were constrained near the cathode. The results of the present work implied that the PIC/MCC model provides an approach to investigate the plasma distribution and a kinetic description of particles for the discharge of the self-field MPDT.

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