Electrospray Collection of Lunar Dust
- Tuesday, 03 January 2012
A report describes ElectroSpray Ionization based Electrostatic Pre cip itation (ESIEP) for collecting lunar dust particles. While some HEPA filtration processes may remove a higher fraction (>99.9 percent) of the particles, the high efficiency may not be appropriate from an overall system standpoint, especially in light of the relatively large power requirement that such systems demand.
The new electrospray particle capture
technology (inspired by the late Nobel
Laureate Dr. John B. Fenn) is described
as a variant of electrostatic precipitation
that eliminates the current drawbacks of
electrostatic precipitation. The new
approach replaces corona prone field
with a mist of highly charged microdroplets
generated by electrospray ionization
(ESI) as the mechanism by which
incoming particles are attracted and
captured. In electrospray, a miniscule
flow rate (microliters/minute) of liquid
(typically water and a small amount of
salt to enhance conductivity) is fed from
the tip of a needle held at a high voltage
potential relative to an opposite counter
electrode. At sufficient field strength, a
sharp liquid meniscus forms (known as a
so-called “Taylor Cone”), which emits a
jet of highly charged droplets that drift
through the surrounding gas and are
collected on the walls of a conductive
tube. Particles in the gas have a high
probability of contact with the droplets
either by adhering to the droplets or
otherwise acquiring a high level of
charge, causing them to be captured on
the collecting electrode as well. The
spray acts as a filtration material that is
continuously introduced and removed
from the gas flow, and thus can never
Experiments determined that ESIEP can collect particles with efficiencies as high as or higher than traditional corona- based EP, owing to the higher specificity of charging and higher levels of charge deposited on particles by the droplets. Removal rates of 95–99 percent and greater are typically observed, even at moderate gas flow rates — all without the generation of ozone due to corona discharge.
This work was done by Joseph Bango and Michael Dziekan of Connecticut Analytical Corp. for Glenn Research Center.
Inquiries concerning rights for the commercial use of this invention should be addressed to NASA Glenn Research Center, Innovative Partnerships Office, Attn: Steven Fedor, Mail Stop 4–8, 21000 Brookpark Road, Cleveland, Ohio 44135. LEW-18629-1
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