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Design and Stress Analysis of Extraterrestrial ... - The Black Vault

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5.2. ION MOTORS<br />

In 'on motors the thrust is created as a result <strong>of</strong> the ejection<br />

into space <strong>of</strong> positively charged particles <strong>of</strong> the working medium<br />

with their subsequent neutralization by electrons.<br />

Ion motors have a maximum specific impulse <strong>of</strong> 50-250 km/s.<br />

possess high efficiency. However, ion motors have comparatively<br />

low thrust from the midsection.<br />

<strong>The</strong>y<br />

We shall briefly examine the classification <strong>of</strong> ion motors.<br />

Based on the method <strong>of</strong> working medium ionization the motors are<br />

divided into two groups: motors with surface ionization <strong>and</strong> motors<br />

with volume ionization <strong>of</strong> the working medium. <strong>The</strong> first group is<br />

subdivided itato two subgroups: motors with high Ionization on<br />

porous tungsten <strong>and</strong> with ionization on smooth tungsten. <strong>The</strong> second<br />

group is subdivided into motors in which working medium ionization<br />

is accomplished in an arc discharge, motors with ionizatJon by<br />

superhigh-frequency currents <strong>and</strong> with ionization by oscillating<br />

discharge.<br />

Based on the design <strong>of</strong> the ion-optical system, the motors are<br />

divided into grid, plate, ring.<br />

Based on the method <strong>of</strong> work-ing medium feed, ion motors can be<br />

classified into several groups: with forced feed <strong>of</strong> 1he working<br />

medium by inert gas, with a wick feed syst,?m, with dosing <strong>of</strong> rhc<br />

working nedium on the basis <strong>of</strong> the elctrolytic princive, with<br />

working medium fed by the inherent pressure <strong>of</strong> sat'4raed vqors.<br />

In view <strong>of</strong> the small expenditu.e <strong>of</strong> working mediunm, the feed<br />

system provides fine regulatlon <strong>of</strong> flov rate, which is a'e-mpiished<br />

by various methods -- capillary, valve, etc.<br />

579

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