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A pulsed 'plasma broom' for dusting off surfaces on Mars

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A pulsed 'plasma broom' for dusting off surfaces on Mars
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Dust is a challenge for the design and operation of equipment on the Martian surface, particularly for solar cells. An efficient and robust technique for removing dust and sand from surfaces immersed in CO2 at low pressure is presented. The working principle is based on a pulsed plasma jet produced between two coaxial electrodes biased at voltages between 1 and 2 kV. A demonstration is presented using dust particles whose chemical composition mimic the Mars soil. An array of connected photovoltaic cells fully covered with dust and sand is exposed to the plasma jet. The cells open circuit voltage is monitored in real-time thus providing the means to measure the dust removal efficiency. A good cleaning efficiency is attained after a few shots in a geometry where the plasma jet is directed perpendicularly to the dusty surface. The main advantage of this approach lies in the opportunity to apply it directly at about 5 Torr, the pressure of the Martian environment. A numerical evaluation shows that the plasma drag force on a dust particle is orders of magnitude higher than its weight depending on plasma density and flow speed, hence validating the principles of this cleaning technique.
Electric power distributionMarsPlasma (physics)Plain bearingComputer animation
Control panel (engineering)RadiationClothing sizesMarsPressurePlanetParticleGasSeparation processComposite materialMarsTypesettingRail transport operationsPlanetElectricityControl rodAtmospheric pressureColor chargeSolar energyJet (brand)ElectrodeElectricity generationGunUltraviolett BCombined cycleBecherwerkBand gapPlasma (physics)SunlightWasserwiderstandAtomhülleDayFrictionChemical substanceTracing paperOrder and disorder (physics)Sauerstoff-16ElectrificationStormControl panel (engineering)SwitchStellar atmosphereMonitorüberwachungSizingMechanicNanotechnologyShip classGround stationSpannungsmessung <Elektrizität>March (territory)Line segmentCooper (profession)LeadMeeting/Interview
Rail transport operationsVoltage
VoltagePlasma (physics)VoltageCorona discharge
MarsPlasma (physics)ParticleForce
Scanning electron microscopeSuperheterodyne receiverMarsParticleVisibilityClothing sizesMitsubishi A6M ZeroPlasma (physics)Cell (biology)Array data structureSeries and parallel circuitsVakuumphysikCosmic distance ladderGunMetreBeleuchtungsstärkeMarsDayComputer animation
Cell (biology)Cell (biology)DayGemstoneFoot (unit)PagerSolar cellComputer animationDiagram
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Transcript: English(auto-generated)
Mars is a dusty planet. Dust particles can become a challenge for the operation of equipments on the surface of Mars. Particularly, solar panels are affected by dust, which will decrease the power production by blocking the sun rays at a rate of 0.3% per day.
The fine dust particles are highly adhered to surfaces due to a combination of factors such as electrification and chemical composition. Dust can be easily electrically charged by UV radiation or by high electrical fields during storms. Dust with a high ferric content can be magnetized.
In order to solve this dust contamination problem, several approaches have been proposed. The cleaning efficiency varies largely depending on several factors, from the type of dust removal mechanism, electrical or mechanical, to its implementation and operation. Electrical approaches are contactless, while mechanical ones seem to be affected by the
triple electric effect, which is the inherent charging of the dust particles by friction. Lifting off particles of 1 mm, for example, with electrical fields is a major challenge of the electrical removal techniques. To overcome this deficiency, we proposed a much more robust cleaning technique,
which seems to be very effective for a wide range of particle diameters. From microns to 1 mm and even beyond this size, thus including sand particles. Our technique is much more rapid compared to known methods. Mars atmosphere is composed mainly of carbon dioxide, 95%, nitrogen and argon in just a few percents, and traces of oxygen and carbon monoxide.
The atmospheric pressure at the planet's surface varies between 3.5 and 7.5 T. We proposed a cleaning technique based on a pulse plasma jet fired between coaxial electrodes in the Martian matter.
The advantages of such a cleaning technique are multiple. The gas at the end and load pressure of about 5 T is accelerated to supersonic speed at several kilometers per second, thus eliminating the need for compressed gas at high pressure. And since the pulse discharge lasts for few milliseconds, the drag force exerted upon the plasma is very high.
The coaxial gun producing the plasma jet is composed of two metallic electrodes, an inner rod and a cylindrical shell. The length of the coaxial gap is 65 mm. The gun is powered by a charge capacitor with 500 microfarads triggered by closing a high current switch.
The operating voltage is between 1 and 2 kV. The peak discharge current is between 7 and 14 kV and the plasma pulse duration is about 400 microseconds. The Lorentz force accelerates axially the plasma and ejects it at a speed of a few kilometers per second.
We use a commercially available regulate for simulating the Martian dust called GAC Mars 1D. The dust particles range from 1 micron to 1 minute. We position the coaxial gun at a distance of a few centimeters and we fire consecutive shots towards the dusty surface.
We can see that after each shot, dust is removed and the surface becomes cleaner. We can clean surfaces buried under a thick layer of dust of 1 mm. The energy required to fire at 1 kV is 250 J, while at 2 kV is 1 kJ. The goal is to clean the surface with as little energy as possible.
Considering the solar illuminance at the Mars surface, the amount of energy that can be obtained within one day of exposure is about 320 J. The photovoltaic cell has an area of tens of centimeters squared. Therefore, it should be able to produce its energy required for its own cleaning.