Present status of colloid microthruster technology.

Abstract

Performance tests in the 100-hr range have been conducted for 100-/zlb thruster modules at average specific impulses ranging from 577 to 1135 sec. Three new thruster configurations--bipolar self neutralizing, linear slit, and high-voltage thick needle--have been investigated. A 50-/zlb bipolar module has been run for two 50-hr tests at specific impulses of 700 and 800 sec. A complete micro thruster flight system is being developed for yaw control of a synchronous satellite. One thruster module for this system has accumulated 1500-hr operation (820 hr continuous) in the 800-sec specific impulse range with no degradation. Direct transverse thrust measurements of an electrostatically deflected colloid beam were taken to demonstrate thrust vector control capability. Up to 40-jiilb transverse force was measured for 129-jLilb total thrust. Nomenclature IN= needle current, amp /sp = specific impulse, sec m = mass flow rate, kg/sec q/m = particle charge/mass, coul/kg q/m = average charge/mass, coul/kg T = thrust, /db VN = needle voltage, kv V xtr = extractor voltage, kv r] = beam efficiency Introduction r ¥ 1 HE heavy particle or colloid thruster produces thrust -•-basically in the same fashion as an ion engine, i.e., by electrostatic acceleration of positively charged particles. The neutralization of either beam can be accomplished by the injection of electrons. The similarity stops here. The charged beam in an ion engine consists of a single fixed specific charge and a small number of neutrals; the colloid beam contains charged multimolecular or heavy particles having a narrow velocity dispersion. Its spread in specific charge (q/m) is peaked about an average value which may be shifted over three decades, from less than 200 to over 300,000 coul/kg. For comparison, q/m = 720,000 coul/kg for cesium. It is this ability to vary the position of the peak of the q/m distribution, and therefore the I sp of the heavy particle thruster, which allows mission parameters to be optimized. The colloid thruster concepts described herein have evolved from eight years of joint research and development efforts between the Aero Propulsion Laboratory at Wright-Patterson Air Force Base and TRW Systems. This work has been devoted primarily to developing 1) optimum performance capillary dimensions and geometry, 2) a suitable highperformance propellant, and 3) adequate diagnostic techniques for thruster analysis. In the primary design to be discussed, a capillary tube (Fig.

Review on water electro-sprays and applications of charged drops with focus on the corona-assisted cone-jet mode for High Efficiency Air Filtration by wet electro-scrubbing of aerosols

“…The high surface-to-volume ratio of sprays with a particular interest for low cost, environment friendly and biocompatible water ES, has been applied to various domains, for: -propulsion by "colloidal" thruster in space, where contamination is not allowed except by water (Huberman et al, 1968;Velásquez-García et al, 2006;Alexander et al, 2007;Quang Tran Si et al, 2007;Gamero-Castaño, 2008;Tang HB et al, 2011;Borner et al, 2013;Morris et al, 2013), -agricultural application for crop spraying of water-based solutions of pesticides on fields (Coffee, 1981;Law, 1982), as well as in greenhouses (Geerse et al, 2000), -Gas conditioning in terms of temperature and humidity (Bailey, 1988;Cui et al, 2017), up to odor masking for domestic gas (Ganesan et al, 2016), -gas treatment for pollution abatement of harmful gases and suspended particles in exhaust fumes and smokes, detailed in the section 4, -water treatment as metal extraction (Parmentier et al, 2016), desalination by evaporation (Agostinho et al, 2018) or bio-decontamination (Pyrgiotakis et al, 2012;Machala et al, 2013;Kanev et al, 2014). -monodisperse nano-particles production by ES of sucrose solutions (Chen DR et al, 1995;Kaufman, 2000) now developed and sold by TSI™ and Ramem™ as size-calibrated aerosol generators.…”