Magnetoplasmadynamic thrusters

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docm

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A look at the future;<br /><br />http://www.nasa.gov/centers/glenn/about/fs22grc.html<br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>Glenn is currently developing high-specific-impulse, megawatt-class, hydrogen-fueled MPD thruster technology. Research at Glenn encompasses a combination of systems analysis, numerical modeling, and high-power experiments that investigate pulsed versions of both self-field and applied-field MPD thrusters. Testing for these thrusters has demonstrated exhaust velocities of 100,000 meters per second (over 200,000 mph) and thrust levels of 100 Newtons (22.5 pounds) at power levels of 1 megawatt. For perspective, this exhaust velocity will allow a spacecraft to travel roughly 11 times the top speed of the space shuttle (18,000 mph).<p><hr /></p></p></blockquote> <br />By comparison Deep Space One developed 92 millinewtons (~1/3 ounce) of thrust. <br /><br />They operate best at very high power, most likely fueled by a nuclear reactor in actual practice.<br /><br />Below the megawatt MPD thruster @ Glenn <div class="Discussion_UserSignature"> </div>
 
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larper

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<blockquote><font class="small">In reply to:</font><hr /><p>For perspective, this exhaust velocity will allow a spacecraft to travel roughly 11 times the top speed of the space shuttle (18,000 mph).<p><hr /></p></p></blockquote><br />Layman technobabble.<br /><br />Just because the numbers 200,000mph/18000mph = about 11 does not mean that the numbers have anything to do with each other. <div class="Discussion_UserSignature"> <p><strong><font color="#ff0000">Vote </font><font color="#3366ff">Libertarian</font></strong></p> </div>
 
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lukman

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WEW, maybe one day we can make it around 3000x faster than 100,000m/s, making it speed of light. <div class="Discussion_UserSignature"> </div>
 
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blazincajun

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That's fast. <div class="Discussion_UserSignature"> </div>
 
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lukman

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I dont agree with you, ion drive is different with rocket system. Indeed, ion has less thrust level, but it has an amazingly exhaust velocities. It will never be used to replace current hydrogen powered rocket to take spacecraft into escape velocities. Instead Ion will be used in the space, since it has low thrust but high exhaust velocities, principally, the ion drive space craft will accelerate very slowly in the space but steadily into 200,000mph. FYI, ion drive is not new, they are just improving efficiency, thrust and exhaust speed. Also, solar panel is enough to run the ion drive. <div class="Discussion_UserSignature"> </div>
 
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bonzelite

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it seems that the thrust would need to be ramped up well beyond 10,000 Newtons or something outrageous like that to lift rockets out of escape velocity. <br /><br />
 
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blazincajun

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Well now if we can put this to use and go 200,000 mph we just need somewhere to go.<br /><br />my question is how would we stop? <div class="Discussion_UserSignature"> </div>
 
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docm

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The technique is to accelerate 50% of the way there then turn the ship around and <b>de</b>celerate the rest of the way to the destination.<br /><br />Let's also not ignore that these things can not only be scaled up in size/power for each thruster but they can also be used in <i>arrays</i>. <br /><br />Use a big enough reactor to power a massed thruster array(s) then fire them 24/7 for weeks/months and you're gonna end up going very, <i><b>very</b></i> fast.<br /><br />@larper;<br /><br />those velocity numbers relative to the Shuttle were NASA/Glenn's (<b>read</b> the link), so if you think they're "Layman technobabble" please take it up with them <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> </div>
 
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nexium

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Never is a long time, so perhaps some day a type of ion engine will lift space craft out of deep gravity wells, but we are looking at about a million times improvement in the thrust to weight ratio. The 200,000 meter per second is mostly about reduced reaction mass that needs to be expelled, for a given amount of thrust. To caclulate the top speed we need to consider with respect to what, and how long we can accelerate, as well as the gravity gradient. Neil
 
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robnissen

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You are missing the point. The way interplanetary ships are powered today is that a chemical rocket (or the space shuttle) is used to get them to NEO and then a smaller chemical rocket is used to break earth's gravity. After that, they mostly just coast (with possible gravity boosts), with an occasional firing of the chemical rockets for course corrections. TODAY, the same system can be used, but instead of coasting, a small constant increase in thrust can be gained using Ion engines. Over time, amazing speeds can be reached. This is not science fiction, but something that can be done now.
 
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docm

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Exactly! <br /><br />If you apply 100+ Newtons of thrust 24/7/365 and things start to boogie nicely vs. "coast mode". Build an array of multi-megawatt class MPD's & apply a pebble bed nuclear reactors output and things would really happen. <br /><br />Heck, you could tack on a Bigelow Nautilus (or several) for good measure <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> </div>
 
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