Nonlinear oscillations in a cold plasma.
Nonlinear large amplitude electrostatic and electromagnetic oscillations in cold plasma having one dimensional spatial variations and fixed neutralized ion background
Davidson, R. W. C.↗
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Cold Plasma Measurements
We have continued the simulation campaign in support of our ongoing magnetospheric cold plasma research project. This project aims to develop the next-generation particle instruments to measure the properties of the cold particle populations in the Earth’s magnetosphere. For this purpose, simulations have been performed with a Particle-In-Cell (PIC) code called the Curvilinear PIC (CPIC). The code is formulated in curvilinear geometry and couples the standard PIC algorithm with algorithms for the generation and adaptation of the underlaying computational mesh. It conforms to complex objects like spacecraft and it can place more grid points in regions where higher resolution is needed. The code also features a scalable solver based on the multigrid algorithm and it is fully parallelized via domain decomposition and MPI.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
RF-transpond: A 1D coupled cold plasma wave and plasma transport model for ponderomotive force driven density modification parallel to B
The RF-Transpond code couples a fluid plasma transport solver with a frequency domain cold plasma RF wave solver in a 1D domain parallel to a strong background magnetic field. A ponderomotive force term proportional to parallel gradients in the electric field strength is included in the transport model in order to describe ponderomotive effects in the scrape-off layer (SOL) of fusion plasmas. The transport and wave codes are verified independently and a coupled case corresponding to experimental parameters from the LArge Plasma Device (LAPD) is presented. The density perturbation ratio R n , calculated to describe ponderomotive force driven modifications, is up to 20% for the simulation inputs used.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
Nonlinear coupling of whistler waves to oblique electrostatic turbulence enabled by cold plasma
Kinetic simulations and theory demonstrate that whistler waves can excite oblique, short-wavelength fluctuations through secondary drift instabilities if a population of sufficiently cold plasma is present. The excited modes lead to heating of the cold populations and damping of the primary whistler waves. The instability threshold depends on the density and temperature of the cold population and can be relatively small if the temperature of the cold population is sufficiently low. Furthermore, this mechanism may thus play a significant role in controlling amplitude of whistlers in the regions of the Earth's magnetosphere where cold background plasma of sufficient density is present.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
Cold plasma activated CO 2 desorption from calcium carbonate for carbon capture
Cold plasmas powered by the renewable electricity can facilitate CO 2 desorption for carbon capture materials (CaCO 3 ) at low temperatures.
Zhong, Hongtao [Stanford Plasma Physics Laboratory↗
Modulational instability of whistlers in cold plasmas
The paper obtains the modulational stability spectrum of whistlers in cold plasmas taking into consideration both ion motion and relativistic effects. The unstable band is contiguous to Omega sub e/4 and, depending on the plasma density, lies above or below that frequency Omega sub e is the electron cyclotron frequency of the static magnetic field. The relevance of the instability to whistlers in the magnetosphere is discussed.
Brinca, A. L.↗
Evaluation of Low-Pressure Cold Plasma for Disinfection of ISS Grown Produce and Metal Instruments
Low pressure cold plasma, using breathing air as the plasma gas, has been shown to be effective at precision cleaning aerospace hardware at Kennedy Space Center.Both atmospheric and low pressure plasmas are relatively new technologies being investigated for disinfecting agricultural commodities and medical instruments.
low pressure↗
Isolated cold plasma regions: Observations and their relation to possible production mechanisms
Regions of enhanced cold plasma, isolated from the main plasmasphere along the Explorer 45 orbit on the equatorial plane, are reported using the sheath induced potentials seen by the electric field experiment. The occurrence of these regions has a strong correlation with negative enhancements of Dst, and their locations are primarily in the noon-dusk quadrant. The data support the concept that changes in large scale convection play a dominant role in the formation of these regions. Plasmatails that are predicted from enhancements of large scale convection electric fields in general define where these regions may be found. More localized processes are necessary to account for the exact configuration and structure seen in these regions and may eventually result in detachment from the main plasmasphere.
Maynard, N. C.↗
Isolated cold plasma regions - Observations and their relation to possible production mechanisms
Regions of enhanced cold plasma, isolated from the main plasmasphere along the Explorer 45 (53-A) orbit in the equatorial plane, have been detected by using the sheath-induced potentials seen by the electric field experiment. The occurrence of these regions has a strong correlation with negative enhancements of Dst, and their locations are primarily in the noon-dusk quadrant. The data support the concept that changes in large-scale convection play a dominant role in the formation of these regions. Plasma tails that are predicted from enhancements of large-scale convection electric fields in general define where these regions may be found. More localized processes are necessary to account for the exact configuration and structure seen in these regions and may eventually result in detachment from the main plasmasphere.
Maynard, N. C.↗
Effect of argon and hydrogen on deposition of silicon from tetrochlrosilane in cold plasmas
The roles of Ar and H2 on the decomposition of SiCl4 in cold plasma were investigated by Langmuir probes and mass spectrometry. Decomposition of the reactant by Ar only has been found to be very slow. In presence of H2 in the plasma SiCl4 is decomposed by fast radical-molecule reactions which are further enhanced by Ar due to additional ion-molecule reactions in which more H radicals are produced. A model for the plasma-surface interactions during deposition of mu-Si in the Ar + H2 + SiCl4 system is presented.
Manory, R. R.↗
Cold Plasma IC Report
This past year we completed the simulation campaign in support of our magnetospheric cold plasma research project. This project aimed to develop the next-generation particle instruments to measure the properties of the cold particle populations in the Earth’s magnetosphere.
58 GEOSCIENCES↗
Numerical simulation of filling a magnetic flux tube with a cold plasma: Anomalous plasma effects
Large-scale models of plasmaspheric refilling have revealed that during the early stage of the refilling counterstreaming ion beams are a common feature. However, the instability of such ion beams and its effect on refilling remain unexplored. In order to learn the basic effects of ion beam instabilities on refilling, we have performed numerical simulations of the refilling of an artificial magnetic flux tube. (The shape and size of the tube are assumed so that the essential features of the refilling problem are kept in the simulation and at the same time the small scale processes driven by the ion beams are sufficiently resolved.) We have also studied the effect of commonly found equatorially trapped warm and/or hot plasma on the filling of a flux tube with a cold plasma. Three types of simulation runs have been performed.
Singh, Nagendra↗
The effects of cold plasma on the Kelvin-Helmholtz instability
The results are presented of a detailed study that examines the effects of cold plasma on the Kelvin-Helmholtz instability. Both electrostatic and electromagnetic modes are considered. The interest in the Kelvin-Helmholtz instability stems from observations of low frequency waves in the polar cusp, magnetopause, in fast moving auroral forms, the plasma pause, and other regions of magnetospheric flow boundaries. It is pointed out that the Kelvin-Helmholtz instability is driven by a velocity shear and can excite a broad spectrum of wave frequencies below the ion gyrofrequency. A model is obtained of a flow boundary that includes a density gradient perpendicular to the velocity shear. The analysis shows a compressional component in Kelvin-Helmholtz waves.
Melander, B. G.↗
Resonance absorption of propagating fast waves in a cold plasma
Absorption of propagating waves impinging on a surface in which the plasma and magnetic field may change is investigated by examining in depth the problem of a combination of cold plasma, uniform magnetic field and a surface density which varies linearly from zero at the left end to some finite value at the right end, beyond which the density is constant. Two cases are considered: one in which the plasma is a vacuum everywhere to the left of the surface (which may correspond to coronal conditions) and one in which the plasma density jumps to a very large value to the left of the surface (which may mimic the magnetosphere with the dense region at the left corresponding to the plasmasphere). A complete discussion of the resonance absorption of propagating fast waves for the case considered by Kiveloson and Southwood (1986) is presented, emphasizing approximate analytical results whenever possible; these results are then compared with exact numerical solutions.
Hollweg, Joseph V.↗
A hierarchal model for bacterial cell inactivation in solution by direct and indirect treatment using cold atmospheric plasmas
Cold atmospheric plasma devices have shown promise for a variety of plasma medical applications, including wound healing and bacterial inactivation often performed in liquids. In the latter application, plasma-produced reactive oxygen and nitrogen species (RONS) interact with and damage bacterial cells, though the exact mechanism by which cell damage occurs is unclear. Computational models can help elucidate relationships between plasma-produced RONS and cell killing by enabling direct comparison between dissimilar plasma devices and by examining the effects of changing operating parameters in these devices. In biological applications, computational models of plasma-liquid interactions would be most effective in design and optimization of plasma devices if there is a corresponding prediction of the biological outcome. In this work, we propose a hierarchal model for planktonic bacterial cell inactivation by plasma produced RONS in liquid. A previously developed reaction mechanism for plasma induced modification of cysteine was extended to provide a basis for cell killing by plasma-produced RONS. Results from the model are compared to literature values to provide proof of concept. Differences in time to bacterial inactivation as a function of plasma operating parameters including gas composition and plasma source configuration are discussed. Results indicate that optimizing gas-phase reactive nitrogen species production may be key in the design of plasma devices for disinfection.
59 BASIC BIOLOGICAL SCIENCES↗
Secular and nonsecular behavior for the cold plasma equations
Secular and nonsecular behavior for nonlinear cold electron plasma equations
NONLINEAR EQUATION↗
Simulation of whistler waves excited in the presence of a cold plasma cloud - Implications for the CRRES mission
A one-dimensional electromagnetic particle simulation model is constructed to study the excitation of whistler waves in the presence of a cold plasma cloud for conditions representative of those after the release of lithium in the inner plasma sheet during the Combined Release and Radiation Effect Satellite mission. The results indicate that a standing-wave pattern with discrete wave frequencies is formed within the cloud. The magnetic wave amplitude inside the cloud, which is limited by quasi-linear diffusion, is of the order of several nanoteslas. Assuming a magnetospheric loss cone of 5 deg, the observed pitch angle diffusion produced by the whistler waves is sufficient to put the electrons on strong diffusion.
Pritchett, P. L.↗
On the stability of self-consistent large amplitude waves in a cold plasma. I - Transverse circularly polarized waves in the absence of a large scale magnetic field
It is demonstrated that a self-consistent circularly polarized wave in an otherwise field-free homogeneous cold plasma is unstable to small amplitude perturbations. For either an electron-positron plasma or an electron-proton plasma the instability rate is at least about the order of the effective plasma frequency when the bulk flow speed is zero. For finite bulk flow speeds of the plasma, it is shown that the electron-positron plasma is unstable, again with a growth rate of the order of the effective plasma frequency; it is also shown that the electron-proton plasma is unstable (at least at small wave numbers, k) with a growth rate proportional to k. The calculated instability rates are conservative, for other modes not investigated here may be more unstable. The results of these calculations bear directly on the understanding of plasma systems thought to be driven by large amplitude waves.
Lee, M. A.↗