Multicomponent Plasma Expansion Model for Arc Discharges on Large-Area Solar Arrays

2021 ◽  
pp. 1-9
Author(s):  
Ira Katz ◽  
Bao Hoang ◽  
Kazuhiro Toyoda
Keyword(s):  
Plasma Expansion ◽  
Large Area ◽  
Multicomponent Plasma ◽  
Solar Arrays ◽  
Expansion Model ◽  
Arc Discharges

Plasma expansion produced by a long-pulse CO2 laser

1980 ◽  
Vol 58 (11) ◽  
pp. 1585-1588
Author(s):  
C. R. Neufeld ◽  
J. L. Lachambre
Keyword(s):  
Focal Spot ◽  
Laser Pulses ◽  
Plasma Expansion ◽  
Steady State Regime ◽  
Plasma Ions ◽  
Isothermal Expansion ◽  
State Regime ◽  
Expansion Model ◽  
Long Pulse ◽  
Aluminium Target

We have studied the plasma expansion produced when a 25 ns CO2 laser pulse is focussed onto a massive aluminium target. The maximum laser power density available was 2 × 1012 W cm−2 in a focal spot of approximately 250 μm in diameter. Charge collector measurements of the ions in the blow-off plasma indicate that an isothermal expansion model best describes the motion of the bulk of the plasma ions. Strong competing effects thus seem to inhibit the establishment of the steady-state regime expected for sufficiently long laser pulses, although faint indications of the beginnings of such a trend may be present.

Investigation on Sustained Discharge of Satellite’s Power Harness Due to Plasma from Space Debris Impact

2019 ◽  
Author(s):  
Yuki Mando ◽  
Koji Tanaka ◽  
Takayuki Hirai ◽  
Shirou Kawakita ◽  
Masumi Higashide ◽  
...  
Keyword(s):  
Space Debris ◽  
Internal Resistance ◽  
Low Earth Orbit ◽  
Hypervelocity Impact ◽  
Space Environment ◽  
Earth Orbit ◽  
Large Area ◽  
Solar Arrays ◽  
Sustained Discharge ◽  
Circuit Configuration

Abstract Space debris travels at a velocity of 7-8 km/s in low Earth orbit (LEO) and at 3 km/s in geostationary Earth orbit (GEO). An impact between space debris and spacecraft will result in tremendous damage. In particular, particles less than 1mm in diameter pose a risk of causing permanent sustained discharge (PSD). PSD may affect a satellite’s power system. The effect on solar arrays has been well-studied given their large area, but the effect on the bundle of a satellite’s wire harness (called the power harness) has yet to be clarified, even though the power harness is usually exposed to the space environment without protection. We conducted hypervelocity impact experiments using a two-stage light gas gun, and investigated the risk resulting in PSD from hypervelocity impacts of particles less than 1mm in size. In addition, we compared two kinds of circuit configurations: a more realistic circuit configuration with internal resistance and a circuit configuration without it, so as to investigate whether internal resistance affects the occurrence of PSD. Stainless steel and aluminum oxide projectiles measuring from 0.3 to 1 mm in diameter were gun-accelerated up to 7.16 km/s. Targets entailed a three-layered power harness under a simulated power condition of typical satellites operating in LEO or GEO. As a result, 11 of 28 shots resulted in PSD. With the more realistic circuit configuration we could not confirm any results regarding PSD. We thus found that PSD is less likely to occur in a more realistic circuit configuration.

More on the expansion of a collisionless plasma into the wake of a body

1986 ◽  
Vol 35 (1) ◽  
pp. 119-123 ◽  
Author(s):  
K. H. Wright ◽  
D. E. Parks ◽  
I. Katz ◽  
N. H. Stone ◽  
U. Samir
Keyword(s):  
Collisionless Plasma ◽  
Quantitative Agreement ◽  
Plasma Expansion ◽  
Laboratory Measurements ◽  
Good Quantitative Agreement ◽  
Expansion Model ◽  
Analytical Expressions ◽  
Insight Into ◽  
Recent Laboratory

Recent laboratory measurements of plasma expansion in a plasma wake experiment are compared with analytical expressions which approximate the plasma expansion model of Crow, Auer & Allen. Good quantitative agreement was found between the data and theory for the velocity and position of the ion expansion front. These results provide an important insight into the behaviour of the expansion early in its development.

scholarly journals The Electrodynamic Mechanism of Collisionless Multicomponent Plasma Expansion in Vacuum Discharges: From Estimates to Kinetic Theory

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7608
Author(s):  
Vasily Kozhevnikov ◽  
Andrey Kozyrev ◽  
Aleksandr Kokovin ◽  
Natalia Semeniuk
Keyword(s):  
Plasma Expansion ◽  
Vacuum Discharge ◽  
Interelectrode Space ◽  
Cathode Plasma ◽  
Multicomponent Plasma ◽  
Non Thermal Plasma ◽  
Charged Ions ◽  
Discharge Gap ◽  
Positive Ion ◽  
A Current

This paper is devoted to the study of collisionless multicomponent plasma expansion in vacuum discharges. Based on the fundamental principles of physical kinetics formulated for vacuum discharge plasma, an answer is given to the following question: What is the main mechanism of cathode plasma transport from cathode to anode, which ensures non-thermal metallic positive ion movement? Theoretical modeling is provided based on the Vlasov–Poisson system of equations for a current flow in a planar vacuum discharge gap. It was shown that the non-thermal plasma expansion is of a purely electrodynamic nature, caused by the formation of a “potential hump” in the interelectrode space and its subsequent movement under certain conditions consistent with plasma electrodynamic transportation. The presented results reveal two cases of the described phenomenon: (1) the dynamics of single-component cathode plasma and (2) multicomponent plasma (consisting of multiple charged ions) expansion.

Convergent Beam Electron Diffraction

1978 ◽  
Vol 36 (3) ◽  
pp. 304-315
Author(s):  
G. Lehmpfuhl
Keyword(s):  
Electron Diffraction ◽  
Diffraction Pattern ◽  
Crystal Surface ◽  
Diffraction Spot ◽  
Crystal Thickness ◽  
Large Area ◽  
Electron Microscopic ◽  
Additional Information ◽  
Microscopic Investigations

Introduction In electron microscopic investigations of crystalline specimens the direct observation of the electron diffraction pattern gives additional information about the specimen. The quality of this information depends on the quality of the crystals or the crystal area contributing to the diffraction pattern. By selected area diffraction in a conventional electron microscope, specimen areas as small as 1 µ in diameter can be investigated. It is well known that crystal areas of that size which must be thin enough (in the order of 1000 Å) for electron microscopic investigations are normally somewhat distorted by bending, or they are not homogeneous. Furthermore, the crystal surface is not well defined over such a large area. These are facts which cause reduction of information in the diffraction pattern. The intensity of a diffraction spot, for example, depends on the crystal thickness. If the thickness is not uniform over the investigated area, one observes an averaged intensity, so that the intensity distribution in the diffraction pattern cannot be used for an analysis unless additional information is available.

TEM Study of a Tilt Boundary in Hot-Pressed Silicon

1981 ◽  
Vol 39 ◽  
pp. 160-161
Author(s):  
C. B. Carter ◽  
J. Rose ◽  
D. G. Ast
Keyword(s):  
Electron Diffraction ◽  
Imaging Technique ◽  
Interface Structure ◽  
Large Area ◽  
Weak Beam ◽  
Lattice Fringe ◽  
Electron Diffraction Technique ◽  
Tilt Boundaries ◽  
Beam Technique ◽  
Twist Boundaries

The hot-pressing technique which has been successfully used to manufacture twist boundaries in silicon has now been used to form tilt boundaries in this material. In the present study, weak-beam imaging, lattice-fringe imaging and electron diffraction techniques have been combined to identify different features of the interface structure. The weak-beam technique gives an overall picture of the geometry of the boundary and in particular allows steps in the plane of the boundary which are normal to the dislocation lines to be identified. It also allows pockets of amorphous SiO2 remaining in the interface to be recognized. The lattice-fringe imaging technique allows the boundary plane parallel to the dislocation to be identified. Finally the electron diffraction technique allows the periodic structure of the boundary to be evaluated over a large area - this is particularly valuable when the dislocations are closely spaced - and can also provide information on the structural width of the interface.

P20 phosphor on polyimide as a large area high-resolution transmission screen for slow scan CCD systems

1995 ◽  
Vol 53 ◽  
pp. 20-21
Author(s):  
C. C. Ahn ◽  
S. Karnes ◽  
M. Lvovsky ◽  
C. M. Garland ◽  
H. A. Atwater ◽  
...  
Keyword(s):  
Mechanical Stability ◽  
High Energy ◽  
Practical Implementation ◽  
Line Pair ◽  
Modulation Transfer ◽  
Large Area ◽  
Ccd Imaging ◽  
Transmission Electron ◽  
The One ◽  
Beam Broadening

The bane of CCD imaging systems for transmission electron microscopy at intermediate and high voltages has been their relatively poor modulation transfer function (MTF), or line pair resolution. The problem originates primarily with the phosphor screen. On the one hand, screens should be thick so that as many incident electrons as possible are converted to photons, yielding a high detective quantum efficiency(DQE). The MTF diminishes as a function of scintillator thickness however, and to some extent as a function of fluorescence within the scintillator substrates. Fan has noted that the use of a thin layer of phosphor beneath a self supporting 2μ, thick Al substrate might provide the most appropriate compromise for high DQE and MTF in transmission electron microcscopes which operate at higher voltages. Monte Carlo simulations of high energy electron trajectories reveal that only little beam broadening occurs within this thickness of Al film. Consequently, the MTF is limited predominantly by broadening within the thin phosphor underlayer. There are difficulties however, in the practical implementation of this design, associated mostly with the mechanical stability of the Al support film.

Study of Tip-Surface Interactions in Scanning Tunneling Microscopy (STM) by Reflection Electron Microscopy (REM)

1990 ◽  
Vol 48 (1) ◽  
pp. 320-321
Author(s):  
W. Lo ◽  
J.C.H. Spence ◽  
M. Kuwabara
Keyword(s):  
High Resolution ◽  
Elastic Strain ◽  
Tunneling Current ◽  
Surface Damage ◽  
Surface Interactions ◽  
Graphite Surface ◽  
Scanning Tunneling ◽  
Large Area ◽  
Tunneling Microscopy ◽  
High Resolution Tem

Work on the integration of STM with REM has demonstrated the usefulness of this combination. The STM has been designed to replace the side entry holder of a commercial Philips 400T TEM. It allows simultaneous REM imaging of the tip/sample region of the STM (see fig. 1). The REM technique offers nigh sensitivity to strain (<10−4) through diffraction contrast and high resolution (<lnm) along the unforeshortened direction. It is an ideal technique to use for studying tip/surface interactions in STM.The elastic strain associated with tunnelling was first imaged on cleaved, highly doped (S doped, 5 × 1018cm-3) InP(110). The tip and surface damage observed provided strong evidence that the strain was caused by tip/surface contact, most likely through an insulating adsorbate layer. This is consistent with the picture that tunnelling in air, liquid or ordinary vacuum (such as in a TEM) occurs through a layer of contamination. The tip, under servo control, must compress the insulating contamination layer in order to get close enough to the sample to tunnel. The contaminant thereby transmits the stress to the sample. Elastic strain while tunnelling from graphite has been detected by others, but never directly imaged before. Recent results using the STM/REM combination has yielded the first direct evidence of strain while tunnelling from graphite. Figure 2 shows a graphite surface elastically strained by the STM tip while tunnelling (It=3nA, Vtip=−20mV). Video images of other graphite surfaces show a reversible strain feature following the tip as it is scanned. The elastic strain field is sometimes seen to extend hundreds of nanometers from the tip. Also commonly observed while tunnelling from graphite is an increase in the RHEED intensity of the scanned region (see fig.3). Debris is seen on the tip and along the left edges of the brightened scan region of figure 4, suggesting that tip abrasion of the surface has occurred. High resolution TEM images of other tips show what appear to be attached graphite flakes. The removal of contamination, possibly along with the top few layers of graphite, seems a likely explanation for the observed increase in RHEED reflectivity. These results are not inconsistent with the “sliding planes” model of tunnelling on graphite“. Here, it was proposed that the force due to the tunnelling probe acts over a large area, causing shear of the graphite planes when the tip is scanned. The tunneling current is then modulated as the planes of graphite slide in and out of registry. The possiblity of true vacuum tunnelling from the cleaned graphite surface has not been ruled out. STM work function measurements are needed to test this.

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