scholarly journals A comparison of contact charging and impact ionization in low-velocity impacts: implications for dust detection in space

2021 ◽  
Vol 39 (3) ◽  
pp. 533-548
Author(s):  
Tarjei Antonsen ◽  
Ingrid Mann ◽  
Jakub Vaverka ◽  
Libor Nouzak ◽  
Åshild Fredriksen
Keyword(s):  
Shock Wave ◽  
Impact Ionization ◽  
Dust Particles ◽  
Low Velocity ◽  
Direct Ionization ◽  
Contact Charging ◽  
Naturally Occurring ◽  
Metal Metal ◽  
Dust Detection ◽  
Volume Ionization

Abstract. We investigate the generation of charge due to collision between projectiles with sizes below ∼1 µm and metal surfaces at speeds ∼0.1 to 10 km s−1. This corresponds to speeds above the elastic limit and well below speeds where volume ionization can occur. Impact charge production at these low to intermediate speeds has traditionally been described by invoking the theory of shock wave ionization. By looking at the thermodynamics of the low-velocity solution of shock wave ionization, we find that such a mechanism alone is not sufficient to account for the recorded charge production in a number of scenarios in the laboratory and in space. We propose a model of capacitive contact charging that involves no direct ionization, in which we allow for projectile fragmentation upon impact. Furthermore, we show that this model describes measurements of metal–metal impacts in the laboratory well. We also address contact charging in the context of ice-on-metal collisions and apply our results to rocket observations of mesospheric dust. In general, we find that contact charging dominates at speeds of up to a few kilometres per second and complements shock wave ionization up to speeds where direct ionization can take place. The conditions that we consider can be applied to dust particles naturally occurring in space and in Earth's upper atmosphere and their direct impacts on rockets, spacecraft, and impacts of secondary ejecta.

scholarly journals A Comparison of Contact Charging and Impact Ionization in Low Velocity Impacts: Implications for Dust Detection in Space

2020 ◽  
Author(s):  
Tarjei Antonsen ◽  
Ingrid Mann ◽  
Jakub Vaverka ◽  
Libor Nouzak ◽  
Åshild Fredriksen
Keyword(s):  
Impact Ionization ◽  
Interplanetary Space ◽  
Dust Particles ◽  
Low Velocity ◽  
Charge Generation ◽  
Earth’S Atmosphere ◽  
Contact Charging ◽  
Metal Metal ◽  
Dust Detection ◽  
Earth's Atmosphere

Abstract. We investigate the generation of charge during collision of projectiles with sizes below ~ 1 μm and metal surfaces at speeds ~ 0.1 km/s. This corresponds to speeds above the elastic limit and well below speeds where volume ionization can occur. The conditions that we consider apply to dust particles naturally occurring in space and in Earth's upper atmosphere and their direct impacts on rockets, spacecraft, and impacts of secondary ejecta. We introduce a model of capacitive contact charging in which we allow for projectile fragmentation upon impact, and show that this model describes measurements of metal-metal impacts in the laboratory and in-situ measurements of dust in the Earth's atmosphere well. We have considered the utilization of our model for different scenarios in interplanetary space and in Earth's atmosphere. From this discussion we find it likely that our work can be employed in a number of situations where impact velocities are relatively small. Furthermore, we have discussed the thermodynamics of the low velocity solution of shock wave ionization, and conclude that the impurity charging effect utilized in the much used model of Drapatz and Michel (1974) does not sufficiently describe charge generation at impact speeds below a few kilometers per second. Consequently, impact charging at low speeds cannot be described with a Saha-solution.

A fragmentation model approach for low velocity impact charging

2020 ◽  
Author(s):  
Tarjei Antonsen ◽  
Ingrid Mann ◽  
Jakub Vaverka ◽  
Libor Nouzak
Keyword(s):  
Impact Ionization ◽  
Low Velocity Impact ◽  
Fragmentation Model ◽  
Low Velocity ◽  
Saha Equation ◽  
Contact Charging ◽  
The Earth ◽  
Volume Ionization ◽  
Model Approach

<p>This work addresses the generation of charge during impacts of nano- to microscale projectiles on metal surfaces at speeds from 0.1 to 10 km/s. These speeds are well above the range of elastic deformation and well below speeds where volume ionization occures. Earlier models have utilized impurity diffusion through molten grains together with a Saha-equation to model impact ionization at these speeds. In this work we employ a model of capacitive contact charging in which we allow for projectile fragmentation upon impact. We show that this model well describes laboratory measurements of metal projectiles impacting metal targets. It also can describe in-situ measurements of dust in the Earth’s atmosphere made from rockets. We also address limitations of the currently most used model for impact ionization.</p>

Development of the flow induced by a piston moving impulsively in a dusty gas

1985 ◽  
Vol 397 (1813) ◽  
pp. 295-309 ◽  
Keyword(s):  
Shock Wave ◽  
Equations Of Motion ◽  
Wave Structure ◽  
Elastic Collision ◽  
Dust Particles ◽  
Dusty Gas ◽  
Impulsive Motion ◽  
Dependent Change ◽  
Piston Speed ◽  
Time Dependent Change

The flow resulting from the impulsive motion of a piston moving at constant speed in a dusty gas is studied analytically and numerically. An idealized equilibrium-gas approximation is used to discuss the effects of piston speed and mass concentration of dust particles on the eventually formed shock wave. The detailed time-dependent change of the flow structure is studied by solving the equations of motion numerically. A partly dispersed shock-wave structure is formed at a high piston speed and a fully dispersed shock at a low piston speed. Two situations are considered, where the particles striking the piston experience an elastic collision, or where they stick to its surface. Significant effects on the flow produced by particles that reflect from the piston surface are discussed and clarified.

Nanodust detection with Cassini CDA - Implications for DESTINY+ and Interstellar Probe

2021 ◽  
Author(s):  
Ralf Srama ◽  
Jon K. Hillier ◽  
Sean Hsu ◽  
Sascha Kempf ◽  
Masanori Kobayashi ◽  
...  
Keyword(s):  
High Resolution ◽  
Impact Ionization ◽  
Cosmic Dust ◽  
Hypervelocity Impact ◽  
Dust Particles ◽  
Interstellar Space ◽  
Mass Spectrometers ◽  
High Resolution Mass ◽  
Resolution Mass

<p>The Cosmic Dust Analyzer (CDA) onboard Cassini characterized successfully the dust environment at Saturn from 2004 to 2017. Besides the study of Saturn’s E ring and its interaction with the embedded moons, CDA detected nanoparticles in the outer Saturn system moving on unbound orbits and originating primarily from Saturn’s E-ring. Although the instrument was built to detect micron and sub-micron sized particles, nano-sized grains were detected during the flyby at early Jupiter and in the outer environment at Saturn. Fast dust particles with sizes below 10 nm were measured by in-situ impact ionization and mass spectra were recorded. What are the limits of in-situ hypervelocity impact detection and what can be expected with current high-resolution mass spectrometers as flown onboard the missions DESTINY+ or EUROPA? Is the sensitivity of Dust Telescopes sufficient to detect nano-diamonds in interstellar space? This presentation summarizes the current experience of in-situ dust detectors and gives a prediction for future missions. In summary, current Dust Telescopes with integrated high-resolution mass spectrometers are more sensitive than the CASSINI Cosmic Dust Analyzer.</p>

scholarly journals Dust detection in solar panel using image processing techniques: A review

2020 ◽  
Vol 9 (8) ◽  
pp. e321985107 ◽  
Author(s):  
Gabriel Moura Dantas ◽  
Odilon Linhares Carvalho Mendes ◽  
Saulo Macêdo Maia ◽  
Auzuir Ripardo De Alexandria
Keyword(s):  
Image Processing ◽  
Monitoring And Evaluation ◽  
Dust Particles ◽  
Solar Panels ◽  
Photovoltaic Panel ◽  
Future Studies ◽  
Image Processing Techniques ◽  
Dust Detection ◽  
Two Parameters ◽  
Processing Techniques

The performance of a photovoltaic panel is affected by its orientation and angular inclination with the horizontal plane. This occurs because these two parameters alter the amount of solar energy received by the surface of the photovoltaic panel. There are also environmental factors that affect energy production, one example is the dust. Dust particles accumulated on the surface of the panel reduce the arrival of light to the solar modules, reducing the amount of generated energy. The cleaning or mitigation of the modules is important and, to optimize these processes, constant monitoring and evaluation must be carried out. In order to increase the efficiency of photovoltaic panels, the use of image processing methods can be considered for the detection of dust. Therefore, the creation of a document that gathers and analyzes the results of different works developed to solve this problem facilitates access to information, allowing a better understanding of what has already been done and how it can be improved. The objective of this article is to review researches that uses image processing techniques to detect dust on solar panels, in order to compile information to assist research in the area and provide inspiration for future studies.

scholarly journals The Cosmic Dust Analyzer: Experimental Evaluation of an Impact Ionization Model

1971 ◽  
Vol 13 ◽  
pp. 299-310
Author(s):  
J. F. Friichtenicht ◽  
N. L. Roy ◽  
D. G. Becker
Keyword(s):  
Mass Spectrometer ◽  
Relative Abundance ◽  
Microprobe Analysis ◽  
Impact Ionization ◽  
Time Of Flight ◽  
Cosmic Dust ◽  
Dust Particles ◽  
Flight Mass Spectrometer ◽  
Fractional Ionization ◽  
The Impact

Determination of the elemental composition of cosmic dust particles by means of an impact ionization time-of-flight mass spectrometer has been investigated at several institutions. In most configurations, the instrument supplies the identity of ion groups of both target and particle materials extracted from the impact plasma and the number of ions contained in each group. Experiments have shown that the fractional ionization of a given species is not constant with impact velocity nor is the fractional ionization the same for different kinds of atoms. A model of the impact ionization effect developed at TRW involves an equilibrium plasma condition with the consequence that the fractional ionization for an arbitrary atomic species can be specified by the Saha equation if the plasma volume (V) and temperature (T) are known. It follows that T can be determined by taking the ratio of the Saha equations for two elements present in the target in known concentration. (Taking the ratio negates the requirement of knowing V.) Given T, the procedure can be reversed to yield the relative abundance of elements contained in the impacting particle. To test the model, a PbZrO3-PbTiO3 target was bombarded with high velocity Fe, MoB, and NiAl particles and the number of Pb, Ti, and Zr ions was determined in a time-of-flight mass spectrometer. For each event, the relative abundance of Ti to Pb was taken as known (from electron microprobe analysis) and T was determined from the Ti-Pb measurement. The Zr to Pb ratio was found to be in good agreement with the microprobe analysis (0.38 calculated mean value compared to 0.34 actual). The result was valid for all particle materials and for a velocity range 17<v<47 km/s. T ranged from 3300 to 11 500° K and was only mildly velocity dependent.

Dust detection by antenna instruments

2020 ◽  
Author(s):  
Zoltan Sternovsky ◽  
Ming-Hsueh Shen ◽  
Michael DeLuca ◽  
Åshild Fredriksen ◽  
Mihály Horányi ◽  
...  
Keyword(s):  
Sampling Rate ◽  
Laboratory Data ◽  
Quantitative Description ◽  
High Rate ◽  
Dust Particles ◽  
Electric Signal ◽  
Accelerator Facility ◽  
Spacecraft Potential ◽  
Dust Detection ◽  
The Impact

&lt;p&gt;Antenna instruments on space missions have been used to detect dust particles and characterize dust populations. The antennas register the transient electric signal generated by the expansion of the impact plasma from the dust impact on the spacecraft body or the antenna. Given the large effective sensitive area, antenna instruments offer an advantage over dedicated dust detectors for dust populations with low fluxes. The dust accelerator facility operated at the University of Colorado has been employed to investigate the physical mechanisms of antenna signal generation. The dominant mechanism is related to the charging of the spacecraft (or antenna) by collecting some fraction of electrons and ions from the impact plasma. We have carried out a number of experimental campaigns in order to characterize the dust impact charge yields from relevant materials, the effective temperatures of dust impact plasmas, and variations of the antenna signals with spacecraft potential, or magnetic field. Here we report on a physical model that provides a good qualitative and quantitative description of the antenna waveforms recorded in laboratory conditions. The model is based on the separation of the electrons from the ions in the impact plasma and their different timescales of expansion. The escaping and collected fractions of charges are driven by the spacecraft potential. Fitting the model to the laboratory data revealed that the electrons in the impact plasma have an isotropic distribution, while ions are dominantly moving away from the dust impact location. Identifying the fine details in the antenna signals requires a relatively high sampling rate and thus not commonly resolved for past instruments. The high-rate mode of the FIELDS instrument on the Parker Solar Probe, however, can be used to verify the proposed model.&lt;/p&gt;

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