A field effect spacecraft neutralizer for the LISA Pathfinder mission

Kent, B. J.; Aplin, Karen; Wang, L; Huq, S. E.; Stevens, Robert S.; Malik, Adnan; Nicolini, Davide

doi:10.1088/0264-9381/22/10/047

Cited by 13 publications

(8 citation statements)

References 4 publications

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“…Some of the possible applications of silicon sharp cone arrays include laser marking of silicon wafers, 11 emitters for field-emission devices, 19 scanning probe microscopy, and solar cell devices.…”

Section: Discussionmentioning

confidence: 99%

Single-pulse excimer laser nanostructuring of silicon: A heat transfer problem and surface morphology

Eizenkop

Avrutsky²,

Georgiev

et al. 2008

Journal of Applied Physics

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We present computer modeling along with experimental data on the formation of sharp conical tips on silicon-based three-layer structures that consist of a single-crystal Si layer on a 1 m layer of silica on a bulk Si substrate. The upper Si layers with thicknesses in the range of 0.8− 4.1 m were irradiated by single pulses from a KrF excimer laser focused onto a spot several micrometers in diameter. The computer simulation includes two-dimensional time-dependent heat transfer and phase transformations in Si films that result from the laser irradiation ͑the Stefan problem͒. After the laser pulse, the molten material self-cools and resolidifies, forming a sharp conical structure, the height of which can exceed 1 m depending on the irradiation conditions. We also performed computer simulations for experiments involving single-pulse irradiation of bulk silicon, reported by other groups. We discuss conditions under which different types of structures ͑cones versus hollows͒ emerge. We confirm a correlation between the presence of the lateral resolidification condition after the laser pulse and the presence of conical structures on a solidified surface.

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Section: Discussionmentioning

confidence: 99%

Single-pulse excimer laser nanostructuring of silicon: A heat transfer problem and surface morphology

Eizenkop

Avrutsky²,

Georgiev

et al. 2008

Journal of Applied Physics

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“…( 5) are important, as if the charge emission continues indefinitely, the electric field at the surface of the aircraft will ultimately become dangerously large, leading to systems failure through electrostatic discharge damage, and possible loss of the aircraft. (In the case of ion thrusters for spacecraft, neutralizers are specifically included to avoid this; e.g., Kent et al 2005. ) This risk can be reduced by approximately balanced emission of positive and negative charge, as then the aircraft charging will be less rapid, determined by the difference in the emission currents which is likely to be smaller than their absolute magnitude.…”

Section: B Requirements For Charge Releasementioning

confidence: 99%

Demonstration of a Remotely Piloted Atmospheric Measurement and Charge Release Platform for Geoengineering

Harrison

Nicoll

Tilley

et al. 2021

Journal of Atmospheric and Oceanic Technology

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Electric charge is always present in the lower atmosphere. If droplets or aerosols become charged, their behaviour changes, influencing collision, evaporation and deposition. Artificial charge release is an unexplored potential geoengineering technique for modifying fogs, clouds and rainfall. Central to evaluating these processes experimentally in the atmosphere is establishing an effective method for charge delivery. A small charge-delivering Remotely Piloted Aircraft has been specially developed for this, which is electrically propelled. It carries controllable bipolar charge emitters (nominal emission current ±5 μA) beneath each wing, with optical cloud and meteorological sensors integrated into the airframe. Meteorological and droplet measurements are demonstrated to 2 km altitude by comparison with a radiosonde, including within cloud, and successful charge emission aloft verified by using programmed flight paths above an upwards-facing surface electric field mill. This technological approach is readily scalable to provide non-polluting fleets of charge-releasing aircraft, identifying and targeting droplet regions with their own sensors. Beyond geoengineering, agricultural and biological aerosol applications, safe ionic propulsion of future electric aircraft also requires detailed investigation of charge effects on natural atmospheric droplet systems.

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“…Fundamental physics missions will require the micro-propulsion system to be in almost continuous operation for the duration of the scientific data collection period. For LISA Pathfinder this is many months and thus a lifetime exceeding 6000 hours was demonstrated Kent et al, 2005).…”

Section: Design and Operating Conditions For Field Emitters For Use I...mentioning

confidence: 99%

Use of coated silicon field emitters as neutralisers for fundamental physics space missions

Aplin

Kent

Collingwood

et al. 2011

Advances in Space Research

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Spacecraft neutralisers are required as part of the ion propulsion system for accurate station keeping in fundamental physics missions. This paper describes the use of thin layers of insulating materials as coatings for the gated silicon field emitter array structure used in a spacecraft neutraliser. These thin coatings are postulated to reduce power consumption and reduce overheating. The power consumption and lifetime of aluminium nitride and amorphous hydrogenated diamond-like carbon coatings have been tested by current-voltage and endurance tests. Diamond-like carbon coatings were promising, performing better in endurance tests than uncoated samples, but further work is required to characterise the coating's physical properties and its effects on field emission. The thermal conductivity of the coating material had little effect on measured sample lifetimes. Aluminium nitride had reduced power consumption compared to diamond-like carbon coated and uncoated samples. A thin (~5 nm) layer of aluminium nitride was found to be optimal, meeting European Space Agency specifications for the neutraliser engineering model.

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A field effect spacecraft neutralizer for the LISA Pathfinder mission

Cited by 13 publications

References 4 publications

Single-pulse excimer laser nanostructuring of silicon: A heat transfer problem and surface morphology

Single-pulse excimer laser nanostructuring of silicon: A heat transfer problem and surface morphology

Demonstration of a Remotely Piloted Atmospheric Measurement and Charge Release Platform for Geoengineering

Use of coated silicon field emitters as neutralisers for fundamental physics space missions

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