COTS to loft VASIMR?

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docm

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<p>FlightGlobal link....</p><p><br /> <img src="http://sitelife.space.com/ver1.0/Content/images/store/2/2/c28dc8dd-79f4-4369-b254-d57f02300af4.Medium.jpg" alt="" /></p><p><strong>Quote:</strong></p><div id="ArticleHeading"><font size="2"><strong> COTS rocket could launch plasma engine to International Space Station</strong></font></div><div id="ArticleHeading">&nbsp;</div> <div id="ArticleAuthor">By Rob Coppinger</div> <span class="noindex"> </span> <p>A scale-model plasma rocket engine that is to be tested at the International Space Station could be delivered in 2012 by a NASA Commercial Orbital Transportation Services (COTS) programme launch system.</p> <p>Houston, Texas-based AdAstraRocket's ISS Variable Specific Impulse Magnetoplasma Rocket (Vasimir) test article will be a scale-model engine similar to the VX-200 prototype being operated in the company's vacuum facility. The ISS test engine will be called Vasimir Flight (VF)200-1 (to denote 200kW and flight one).</p> <p>AdAstraRocket chief executive Franklin Chang-Diaz met NASA on 21 August and was told about the capabilities of Space Exploration Technologies' (SpaceX) Falcon 9. SpaceX and Orbital Sciences are the two companies participating in COTS. </p> <p>Falcon 9 is SpaceX's rocket that would launch its Dragon capsule, and Orbital's Taurus II booster would orbit its Cygnus spacecraft that could have a 2,300kg (5,000lb) cargo capacity for the ISS. None of these COTS vehicles have yet flown.</p><p>"We have a number of options, everything is on the table," says Chang-Diaz. The options include a flight on the Japan Aerospace Exploration Agency's HII Transfer Vehicle. </p> <p>AdAstraRocket was spun out of NASA three years ago and has since signed two agreements with the agency. The third concerns the integration of the VF200-1 test article on station and has been discussed since 2006. Those discussions have seen the scope of the on-station testing change.</p> <p>The Vasimir works by injecting gas, such as hydrogen, into an engine that turns it into a plasma. That plasma is then energised further using radio signals as it flows through the engine, a process controlled by electromagnetic waves from superconducting magnets. Accelerated and heated through this process the plasma is focused and directed as exhaust by a magnetic nozzle. Vasimir is many times more efficient than conventional chemical rockets.</p><p>&nbsp;</p> <div class="Discussion_UserSignature"> </div>
 
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ThereIWas2

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How do they get 200 kW from those puny solar panels? <div class="Discussion_UserSignature"> <p><span class="postbody"><span style="font-style:italic"><br /></span></span></p> </div>
 
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Boris_Badenov

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>How do they get 200 kW from those puny solar panels? <br />Posted by ThereIWas2</DIV></p><p><font size="2">Is that how much power it takes or how much thrust it puts out measured in kilowatts?<br /><br /></font></p> <div class="Discussion_UserSignature"> <font color="#993300"><span class="body"><font size="2" color="#3366ff"><div align="center">. </div><div align="center">Never roll in the mud with a pig. You'll both get dirty & the pig likes it.</div></font></span></font> </div>
 
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shuttle_guy

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Is that how much power it takes or how much thrust it puts out measured in kilowatts? <br />Posted by boris1961</DIV></p><p>200 Kw is the engine output.</p> <div class="Discussion_UserSignature"> </div>
 
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DrRocket

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>200 Kw is the engine output. <br />Posted by shuttle_guy</DIV></p><p>If that is the engine output, what is the electrical input to the engine ?&nbsp; </p> <div class="Discussion_UserSignature"> </div>
 
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shuttle_guy

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>If that is the engine output, what is the electrical input to the engine ?&nbsp; <br />Posted by DrRocket</DIV></p><p>http://www.adastrarocket.com/AIAA2007.pdf<br /></p> <div class="Discussion_UserSignature"> </div>
 
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js117

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>How do they get 200 kW from those puny solar panels? <br />Posted by ThereIWas2</DIV></p><p>Power output of ISS solar array is 110 kW of power available for all uses. after life support, battery charging and other </p><p>power management , 46 kW left over for other uses </p>
 
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Boris_Badenov

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>http://www.adastrarocket.com/AIAA2007.pdf <br />Posted by shuttle_guy</DIV></p><p><font size="2">Those schematics are way beyond me, could you possibly summarize the input & thrust numbers please.<br /><br /></font></p> <div class="Discussion_UserSignature"> <font color="#993300"><span class="body"><font size="2" color="#3366ff"><div align="center">. </div><div align="center">Never roll in the mud with a pig. You'll both get dirty & the pig likes it.</div></font></span></font> </div>
 
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shuttle_guy

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Those schematics are way beyond me, could you possibly summarize the input & thrust numbers please. <br />Posted by boris1961</DIV></p><p>&nbsp;</p><p>They are beyond me as well !!<br /></p> <div class="Discussion_UserSignature"> </div>
 
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Boris_Badenov

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;They are beyond me as well !! <br />Posted by shuttle_guy</DIV></p><p><font size="2">Well, I gave it a shot. I won't say I know how it works, or even that I understand the principals. But, it looks like you feed in volts & you get watts as a result. The input to output ratio appears to be 10 to 1. In other words, you put in 20k volts & you get 200k watts of thrust. The throttleable aspect of the engine seems to be how much power in volts you provide.</font></p><p><font size="2">I know we have some engineers here, maybe one of them can take a look & see if I understood this correctly?</font><br /></p> <div class="Discussion_UserSignature"> <font color="#993300"><span class="body"><font size="2" color="#3366ff"><div align="center">. </div><div align="center">Never roll in the mud with a pig. You'll both get dirty & the pig likes it.</div></font></span></font> </div>
 
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kelvinzero

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<p>I skimmed it&nbsp; (really didnt read in depth and I doubt it would have helped) and found this:</p><p>"<font face="TimesNewRomanPSMT" size="2"><font face="TimesNewRomanPSMT" size="2">The next example of an ICRH experiment that will be presented is a radial scan of the RPA during 14 kW ICRHon conditions. The results have been interpreted using a single Maxwellian and are shown in Figure 15. This experiment was performed with a 20 kW helicon antenna discharge and 450 sccm deuterium gas flow</font></font>"</p><p>and later</p><p>"<font face="TimesNewRomanPSMT" size="2"><font face="TimesNewRomanPSMT" size="2">Since the two curves overlay, the lower total power low flow case was more efficient, achieving an apparent booster efficiency of ~90% and a total power efficiency of ~60% at 20 kW of ICRH power.</font></font>"</p><p>Maybe this total power efficiency figure of 60% is exactly what us laymen would hope? In that first example it implied that 20kw of power produced 14kw of radio energy, (say 70% efficient) and the efficiency of 90% conversion of radio to thrust mentioned might move it down to about that 60% figure?</p><p>Again, I didnt read it carefully at all. just jumped to the summary and read a few other lines and captions.</p><p>Also re previous comments of ISS power vs vasimr requirements: since it is just a test perhaps they just use a capacitor and only test at full power for short durations?</p>
 
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kelvinzero

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Also, even if that 60% figure is accurate, perhaps they are not trying to demonstrate the efficient conversion of power to radiowaves in this device. Maybe they are sacrificing efficiency for a more controlled and versatile experiment.
 
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thor06

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<p>When I first started watchnasatv.com's you tube channel I added all the official NASA you tube channels, as subscriptions.&nbsp; Then hunted around for enthusiast channels that would add to the content.&nbsp; I was blessed to find Dr. Ben Longmier's channel, and have enjoyed following his work ever since.</p><p>&nbsp;</p><p>The engines in question, are his babies.&nbsp; I took the opportunity to reach out to him, and get some answers to your questions.&nbsp; I was not at all sure he would respond, he is a busy guy.&nbsp; Pilot, scuba diver, Post Doc rocket scientist, and one day maybe, astronaut.</p><p>Well he did, and here it is:</p><p><br /><br /> <img src="http://sitelife.space.com/ver1.0/Content/images/store/13/2/7d026c87-1a13-4393-b208-200532cf2e66.Medium.jpg" alt="" /><br /><br /><strong>Dr. Ben Longmier</strong> (weightless)</p><p><span><br /> "It seems that there is some confusion about VASIMR power levels and how this plays into testing on the ISS. One near-term goal of the Ad Astra Rocket Company (AARC) is to test a flight version of VASIMR on the ISS. The goal is to fly sometime ~2013 with a 200 kW rocket. The 200 kW refers to the total power level of radio waves, referred to as RF power, injected into and absorbed by the plasma. However, to complicate things, we plan to fly two 100 kW units side by side. There are smaller systems like cryocoolers and data systems that will draw a few additional kW, but the total power will still be close to 200kW. It's my understanding that when the Station is finished, its solar panels will be able to produce ~128kW, with about 20 kW left over to run all of the science experiments on the Station. This of course means that the VASIMR flight unit, named VF-200 for VASIMR Flight 200 kW, will have to run in a non-steady-state mode. The plan is to carry our own battery pack up to the Station. We would trickle charge the battery from available Station power over the course of a day or several days and then fire VASIMR for minutes to hours, then repeat.<br /> <br /> A few updates about the VF-200.<br /> -argon propellant (produces the optimum exhaust velocity for a 200 kW VASIMR in LEO)<br /> <br /> -high temperature superconducting magnets to produce ~ 2 tesla magnetic field<br /> <br /> -there are two RF stages, 1) ionizes the argon gas into an argon plasma, 2) heats only the argon ions (not the electrons).<br /> <br /> -two 100 kW VASIMR units will be used to form the VF-200. The magnetic field of each 100 kW unit will be antiparallel, which will create a quadrapole magnetic field overall for the VF-200. This is done so that there is no net magnetic field far from the VF-200 and thus does not interact with the Earth&rsquo;s magnetic field and create a torque on the ISS.<br /> <br /> -the VF-200 is designed to produce ~5 N (1.1 lbs) of thrust. At max, the ISS has about 2 N of drag force at its current orbit and less if the solar panels are edge on to the direction of travel. A side point, but the ISS can actually &lsquo;sail&rsquo; using this effect. The drag is caused by a small but finite air pressure at its altitude (~200 miles). Typically a Russian Progress spacecraft is used to bring fresh supplies and reboost the ISS every 6 months because of this drag."</span></p><p>&nbsp;</p><p><strong>He indicated that if we have any more questions, he would be happy to field them.&nbsp; I'll give it a week or so, and if there are further questions I'll compile them and send them to him. </strong></p><p>&nbsp;</p><p>He also added these from students:</p><p><span>"A few common answers to questions I get from students during lab tours:<br /> -there is no top speed for VASIMR, spacecraft speed is only limited on the amount of propellant (and current demonstrated technology keeps us way under light speed)<br /> <br /> -the magnetic field confines the plasma and keeps it away from all material surfaces. A magnetic nozzle converts the ion energy into directed thrust and expels the plasma as exhaust.<br /> <br /> -even though the plasma is super hot, it doesn&rsquo;t have a lot of heat content. This is due to the fact that the plasma has a very low density (one millionth of an atmosphere for VASMIR). i.e. there is no way for VASIMR to blowup should some system fail.<br /> <br /> -a fuel tank of argon used on the ISS will last VF-200 for many years. (probably 6-12 months continues operation at full power...the tank size and launch masses are still being decided)<br /> <br /> -our goal is an overall system efficiency of greater than 60%. This means that of the 200 kW of RF power injected into the plasma stream, />120 kW makes it out into the plasma exhaust plume. The remaining 40% would be radiated as waste UV, visible, and IR light to the rocket body and out into space."</span></p><p> <span>Hope this helps,<br /> Ben</span></p><p>Dr. Ben Longmier's You tube channel </p><p>&nbsp;</p><p><strong>My thanks, and heartfelt appreciation to Dr. Longmier, who goes out of his way to reach out, and share the excitement. </strong></p><p>&nbsp;</p> <div class="Discussion_UserSignature"> <p> </p><p> <font color="#0000ff">                           www.watchnasatv.com</font></p><p>                          ONE PERCENT FOR NASA! </p> </div>
 
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