Z accelerator as propulsion system

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jhoblik

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http://www.sandia.gov/LabNews/ln05-27-05/labnews05-27-05.pdf<br />I would like to discuss idea use Z Accelerator as propulsion system for interplanetary trips. <br />Xenon Ion engine is nice and efficient propulsion but thrust is very low.<br />Z accelerator is able to accelerate aluminum plates to speed 34 km/s(21Miles/s), it is more than actual Ion engine is able to speed up its medium(Xenon).<br />I think also that thrust of Z accelerator could be bigger. As fuel could serve everything what is able to be accelerate in magnetic field. We could use asteroids , Moon(here is plenty of aluminum) and Mars moons to re-supply our interplanetary ships. <br />I couldn’t see weight of this plates,but If these plates weight 1 gram and we will shut them every 5s, 100 tons ship will speed up to escape velocity in 3 month energy supply requirement will be same as 600kW ion engine under development will with thrust ~ 2N.<br />If we will be able speed up speed of plates to 60km/s it will took only 1,5 month to speed up to escape velocity.<br />Am I missing something?<br />
 
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mrmorris

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<font color="yellow">"Am I missing something? "</font><br /><br />I dunno. Did you miss the fact that the Z-accelerator is 120 feet in diameter? Did you miss the fact that the aluminum plate was 850 microns thick? The article unfortunately doesn't give a figure for the power involved. However, this one does: <i>"The Z machine is a pulsed power accelerator consisting of capacitors that, like large batteries, are charged with electricity for more than a minute. The electricity is released in 100 billionths of a second, resulting in a 50 trillion-watt, 18 million-amp pulse. "</i> Any spacecraft using this for acceleration has to be able to generate flipping <b>enormous</b> amounts of electricity.<br /><br />Other than that -- sounds good. <img src="/images/icons/smile.gif" />
 
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chriscdc

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Well CERN can get protons up to 99.9% of light speed. <br />Shame it weighs several thousand tonnes.<br /><br />To be fair there are some pyroelectric materials that, when heated, can generate potential differences that can accelerate particles to decent fractions of the speed of light. They could (after alot of development) act as ultra high ISP engines, shame the thrust will still be tiny. <br /><br />You could however use the Z machine to accelerate plates to propel a space craft. You could have the machine on a moon with no atmosphere. Connect it to several thousand km of solar cells and it might work.
 
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mrmorris

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<font color="yellow">"Energy requiments 2MW, 600kW energy resource gives chance shut every 3 second. "</font><br /><br />Um -- where exactly in that article are you getting those figures? The only quote I can see in reference to something like that is: <i>"They thought about making them small enough to put on the back of a truck or tank, but the problems of size and the issues with the barrels were still there."</i>
 
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tap_sa

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<font color="yellow">The electricity is released in 100 billionths of a second, resulting in a 50 trillion-watt, 18 million-amp pulse. " Any spacecraft using this for acceleration has to be able to generate flipping enormous amounts of electricity. </font><br /><br />Trillions of watts and millions of amps sound enormous but it's the billion<i>th</i> that reduces the total energies involved into quite meager values. 1/100,000,000,000s * 50,000,000,000,000W gives 500Ws (Joules), an amount of energy that your computer consumes in a few seconds. But this isn't enough to propel spacecrafts, only microscopic aluminium particles.<br /><br />We do need a megawatt or two, but the problem isn't the amount of watts per se, it's the W/kg ratio of the power generating equipment. The best solar panels are approaching 1000W/kg (without support structures, cabling). When you mate that with 1000W worth of ion engine (around one kg too) and calculate some practical burntime for manned spaceflights (a few months tops for Mars trip) you discover that it will be rather abysmal amount of propellant that you can burn per said unit ie. your massratio won't be good. Lighter panels (or maybe nuclear power?) and better T/Ws for electric propulsion is required for making shorter trips a reality.<br /><br />I do like the Z-propulsion idea though, aluminium is abundant compared to xenon etc. and in emergency you can start to scavenge the ship itself for more propellant <img src="/images/icons/smile.gif" />
 
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jhoblik

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They said energy requirements is equal energy for 200 homes for 2 minutes.<br />1 home 10 kW<br />200 homes 2MW<br />Or source of energy has to be 40MW.<br />But for all trips we need resource big enough any way, except we will use chemical engines.<br />We have give speed to our ship and it takes energy.<br />It means it is not about if we have energy resource we need that any way, we couldn't depend on the Earth and bring energy from our planet.
 
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mrmorris

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<font color="yellow">"But this isn't enough to propel spacecrafts, only microscopic aluminium particles. "</font><br /><br />Yes -- and once scaled up to the point where it <b>will</b> move spacecraft -- the power levels become enormous... as I said. Everything comes down to how much energy you can pack into the particle providing the reaction thrust.<br /><br />The only way I can see of doing this though is by leaving the engine at home. Build one heckuva powersat, the bigger and heavier the better. Fire aluminum grains at your spacecraft (which much have an armored shock absorber at the rear for the pellets to hit). There are still plenty of problems though... especially as your 'gun' and the spacecraft will soon be on very different orbital paths around the sun and the gun will not be able to continuously provide propulsion. Also -- nothing to decelerate the craft at the other side. I could see a gun like this this used maybe for accelerating cargos from the moon to Earth orbit... but interplanetary distances would be very problematic.
 
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craig42

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<blockquote><font class="small">In reply to:</font><hr /><p><br />Well CERN can get protons up to 99.9% of light speed. <p><hr /></p></p></blockquote><br />What if CERN's collider was to be built near the sun, and used to fire high speed protons at solar sail craft?
 
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holmec

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Great!<br />Now all we need is a power supply big enough to power it, the virtual gravity generator not invented yet. Not to mention the super structural material able to withstand such forces that's not invented yet.<br />WERE 0.00001% THERE! <div class="Discussion_UserSignature"> <p> </p><p><font color="#0000ff"><em>"SCE to AUX" - John Aaron, curiosity pays off</em></font></p> </div>
 
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chriscdc

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It accelerates far too little mass etc. The shielding would have to be impressive just to stop the particles.<br /><br />What if there was a way to harness solar wind to a greater extent than just solar sails or plasma fields.<br />What I imagine is a series of rings connected to a central pole. The pole would be negatively charged and the rings would be positively charged. The rings would be several hundred km across and would redirect plasma from the sun. The system would act as a lense and keep the plasma concentrated further from the sun than it would normally be. The entire system would use solar power and would keep its position by controlling the plasma flow.
 
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dwilson

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One day we will see a plutonium sphere suspended in a magnetic enviorment trapped in a vaccum of a inert gaseous mixture to interact with the polarity coupled to a kw convertor or heat exchange .. then it might run for 100 years or more at around 200 lbs.. <br /><br />Put that under the hood with the Z Drive..<br /><br />Pardon me for interjecting such a fictional proposal in a scientific discussion.. but I could not resist to try to overcome the mass/power ratio .. containment is the true obstacle there.. but I could of just stepped out of bounds.
 
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spacechump

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And just what would your setup accomplish? The decay of plutonium for power is nothing new and throwing the whole setup in a Z pinch machine would only make the sphere denser upon implosion. You're envisioning a mechanism that is somewhere similar to how a nuclear weapon achieves critical mass.
 
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dwilson

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..perhaps you are not open to the possiblity of maintaining the plutonium or such substance or combination of substances in a near critical but stable state.. your assumption is correct if the chain reaction could not be halted on cycle or looped.. which of course has yet to be achieved.. just trying to stimulate discussion that may lead to higher thought.. not just what is currently known possible.. you bring up a more than valid observation.. in the mother of invention and discovery people serve different functions for stimulating the undiscovered.. some are the chisel, some the hammer.. and someone has to be the stone.. cause and effect.. what was unthinkable yesterday, is reality tomorro.. however it may or may not apply to the Z drive.. nuclear driven propulsion is ineviatable.. 10 years.. 20.. 50.. <br /><br />Check this link out.. they do it in small scale stuff already.. http://www.uic.com.au/nip82.htm
 
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spacechump

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Again, nuclear power and propulsion is nothing new even in the discussion of space. But what you're talking of is more like an over-complicated nuclear reactor. Why not just have a confined reactor core like any other reactor design.
 
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nexium

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How much thrust does a typical RTG produce if we vent the stray radiation into the vacuum of space on one side and shield the other sides? Can we scale up this concept? Neil
 
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spacechump

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RTGs don't work that way. They work because of a temperature differential between the cold of space and the heat generated from radioactive decay acting on a thermocouple.<br /><br />If the radiation was vented into space for whatever reason there would be almost null thrust. A better idea is to pass a cold gas over a hot reactor core and vent that. Look up NERVA.
 
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