Talk:Ion thruster
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Who put this german scientisct as pioneer of rocketry? Tsiolkovsky, russian scientist is a pioneer of rocketry and space travel.
[edit] Electric propulsion not ion thruster
Hi i think it would be better if the main page for ion thrusters was electric propulsion. This is how it is done in major engineering books on the subject - see Sutton, Rocket Propulsion Elements, or Stark, Fortescue etc, Spacecraft systems engineering. Then electric propulsion is divided into 3 categories; 1. electrostatic propulsion 2. electromagnetic propulsion 3. electrothermal propulsion
Then the different types of electric propulsion (they are many!) are listed in their relevent categories. So ion thrusters would be in electrostatic propulsion, whilst arcjets would be in electrothermal propulsion. Is it ok with ppl if i do this? Can i do this?! Charlie
- Since ion propulsion is really the only form of electric propulsion that has actually been used, I think it deserves it's own article. We could have another article that discusses other possibilities for electric propulsion, but this article should stay as it is.--Mars2035 19:42, 5 May 2007 (UTC)
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- There are some types of electric propulsion engines which are not ion engines (i.e., utilize ions) such as resistojets and arcjets which have flown. I think this is addressed in the general EP article --Allen314159 00:02, 3 July 2007 (UTC)
Hello again i think this page should not contain the scientific backround to spracesraft electric propulsion - that should be contained on the 'electric propulsion' page. It is not right at all to characterise electric propulsion used on spacecraft as ion thrusters, and is a little misleading - for example colloid thrusters are not ion thrusters, as they do not use ions as the propellant, but charged droplets, much larger than an individual ion. This page should focus more specifically on on the classic electrostatic ion thruster, as used on deep space 1. And i guess a short piece on the fictional use of ion thrusters would be appropriate. It should not be the main page that lists the different type of spacecraft electric propulsion - that should be the 'spacecraft electric propulsion' page - a page that currently called the slightly misleading 'electric propulsion'. Cheers --nasalcherry
[edit] Craft charge
Question:
Why is it important that the Ion thruster driven space engine stays electrically neutral? I tend to think that in an almost perfect vacuum (outer space) electrical charge doesn't matter. Because charge is relative to its surroundings - basically nothing in space.
Or is there still too much dust around in "empty" space?
Or is there electrical attraction to be expected from really far away objects (say, a planet)?
- Charge isn't relative: like mass, it's a property of the object, whether or not there's anything nearby to be affected by it. Also, ion drives are being used in places that are, in terms of particles, far from empty, like near-Earth space. Vicki Rosenzweig 11:59, 29 Sep 2003 (UTC)
The problem with needign to remain electricalyl neutral is that if the chassis becomes too electrically negative, then the device must perform extra work to remove the extra electrons adn ionize the workign fluid, plus the exhaust beign still ionized would be attracted to the highly negative chassis instead fo open space, producing no thrust. Its far more complex than that but the explanation should suffice.
[edit] Deep Space 1
Also it needs to be noted in here that DS-1 will NOT be using an ION engine it will be using a HALL EFFECT engine, the difference is technical but ion drives are no longer used for future designs.
Au contrare! DS-1 used the xenon ion thruster developed under the JPL NSTAR program, it was definitely a gridded ion thruster, not a Hall thruster.
[edit] Limits to specific impulse
My understanding of ion engines is that they can increase their specific impulse simply by increasing the grid voltage. However, they normally only operate with an isp of about 3000 because higher isp values would require too much power to produce a decent thrust. Is there any practical limit to how high the grid voltage and isp can get if power supply is not a problem? Could an ion engine vary its isp over a wide range of values by changing the ratio of power being used to ionize fuel to the power being used to accelerate the fuel?--Todd Kloos 23:01, 9 Jun 2004 (UTC)
- Yes and no; ion drives have problems with ions striking electrodes and eroding the electrodes. If you just crank up the voltage, the ions will start to wreck the electrodes. Other problems may also occur; I'm guessing, but you may also have to avoid arcing and corona discharge in the ion stream, and there may be other concerns as well. But certainly power consumption is a major design issue: you have to trade off the mass of fuel required against the mass of the power generation equipment. For very large delta-v (comparable to the specific impulse) improving specific impulse is a very big win. But if delta-v is relatively small compared to exhaust speed, then the reaction mass is not very large, so boosting specific impulse may require you to increase launch weight to generate enough power. This becomes worse when you want to travel far from the sun; power generation gets more difficult, and if it requires an expendable resource, you might as well throw the expended resource out the back as extra reaction mass. --Andrew 06:53, 11 Jun 2004 (UTC)
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- Thank you for replying. I know that the current generation of ion thrusters (HiPEP) has very significant advantages in thruster lifetime compared with previous ion engines. Presumably this would also allow higher voltages without wrecking the electrodes? Anyway, I know that higher specific impulse is not always better. However, for many missions using a constant isp value is not the most efficient way. I have seen profiles for optimized VASIMR missions to Mars where the spacecraft will start out with an isp of 3000, but the isp will slowly rise during the trip (sometimes reaching a peak as high as 50,000) before going back down to 3000 at the end of the trip. If ion engines can go through a similar variation of specific impulse, it should allow them to increase efficiency shorten mission durations considerably.--Todd Kloos 08:05, 11 Jun 2004 (UTC)
[edit] Scotty Quote
Uh, unless my understanding of wikipedia format is totally off, the quote by Scotty is not appropriate
- Personally, I'd like to know which episode that was. 65.60.222.179 11:24, 15 January 2006 (UTC)
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- So what happened to the star trek reference? It was widely cited in the press in the coverage of the Deeps Space 1 probe. It was the Spock's Brain episode. Here are some relevent references.[1][2][3]. Unless someone has a meaningful objection I am going to restore some kind of reference to this. It is notable enough to mention and there is a long history of interaction between the space program and SF especially Star Trek. Rusty Cashman 04:18, 28 September 2007 (UTC)
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- Probably because it's meaningless buzzwords in Star Trek and the depiction of the the ion drive bears little relationship to what ion drives are, or how they behave.WolfKeeper 11:58, 28 September 2007 (UTC)
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[edit] Freelancer Speculation
The following quote from the fiction section of the article is gibberish to me:
The engine exhaust is visible (relatively) low frequency energy pulses and some fans theorize this could be achieved with a form of electromagnetic flux compression to ramp up the power output of the reactor.
If it's gibberish to someone else (ie, it's not just me), could it be simply deleted?
- What they're describing is a pulsed fusion reaction, where you increase the magnetic confinement field's strength to compress the plasma, which substantially increases the rate of fusion. I'll try to clean it up. --Christopher Thomas 16:08, 6 January 2006 (UTC)
[edit] Delta V?
From the article, under missions: "Of all the electric thrusters, ion thrusters have been the most seriously considered commercially and academically in the quest for interplanetary missions. Ion thrusters are seen as the best solution for these missions as interplanetary trajectories require very high delta V (the overall change in velocity, taken as a single value) that can be built up over long periods of time (years)." This seems wrong. What's important is a very high _average_ velocity, and that can be built up over many years. A high average acceleration doesn't come into it except in that it in turn implies a high average velocity.
- You seem to have misunderstood slightly. Delta-v isn't acceleration. Delta-v is (basically) the total speed change the vehicle would get if you were to accelerate it in a straight line, without gravity, until you run out of fuel.
- Also actual velocity isn't right at all. For example, as a vehicle climbs higher and higher in an orbit around the Earth or the Sun or whatever, it actually slows down. It's all a bit counterintuitive; but as you drop into lower orbits the speed goes up, as you climb it goes down. But you're spending delta-v to do either manouever.
- Sorry, bet that's clear as mud.WolfKeeper 17:19, 3 October 2005 (UTC)
[edit] Imperial Units
Please clear the article of them or at least make SI units the primary unit.
[edit] Illustration
Would this one be worth using as a base for an illustration here? Scoo 21:53, 14 December 2005 (UTC)
[edit] TIE Fighters?
Should some mention of Ion Thrusters in fiction be made? Like, you know, the TIE Fighter. Twin Ion Engine - TIE. Not sure if it's appropriate, but it is a significant cultural thing (Star Wars, not Ion thrusters). --Phant 21:49, 2 June 2006 (UTC)
- The 'ion drives' that are depicted show little if anything in common with the real thing.WolfKeeper 12:00, 28 September 2007 (UTC)
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- Seems pretty in common to me. Using ion engines to propel vessels through the vacuum of space. Perhaps it could be in the See Also section.(Myscrnnm 23:27, 5 November 2007 (UTC))
[edit] Video of Running Ion Drive
I did some google searching and looking on here and no where on the internet can I find any video of an ion drive actually running. I am personally very curious on how the beam of particles looks in motion, and if there is any wobble or anything else of that matter. If anyone has a link to a video, has a video themselves, or knows someone who does, please put it on the net and on Wikipedia as well.
- Found this, it's timelapsed and no sound and real bad quality. http://nmp.jpl.nasa.gov/ds1/tech/ds1_ips.mov If I find another one I'll add that. --62.220.161.10 06:55, 31 August 2006 (UTC)
[edit] Ion thruster page edits
Hi, I'm a student at the University of Wisconsin - Madison and I'm editing this page as a project for my technical editing class. I'm also majoring in Engineering Mechanics and Astronautics and I've also done quite a bit of research on ion engines. I would appreciate it if you would hold off on editing things I've changed for a day or so until I'm finished (i'll edit this to let you know). Sorry if I changed your stuff (Wolfkeeper). I'll leave an explanation here as to the major things I've done as well. Thanks a lot. Dmpdpete (talk) 00:23, 20 November 2007 (UTC)
- The problem is that this page is a general page on ion thrusters, whereas there's a good page on gridded electrostatic ion thrusters that covers what your edits were referring to. I'll leave off editing from now on though.WolfKeeper (talk) 00:42, 20 November 2007 (UTC)
- (I only just saw this, sorry about that. :-( )WolfKeeper (talk) 00:43, 20 November 2007 (UTC)
- Somewhere, there's a tag for use when you're making changes, but you prefer others not to edit until you've finished, you should probably dig it up and apply it.WolfKeeper (talk) 00:46, 20 November 2007 (UTC)
No worries and thanks. I think I should be good. Regarding the other pages, I feel the the electric propulsion page is a good general ion thruster page and from what I've read when someone refers to ion thrusters, its an electrostatic one. There's no set definition though. I'm just editing this one as kind of a mix of general and electrostatic specifically and then when I'm done I would probably suggest this and the electrostatic page get merged or something. Dmpdpete (talk) 00:52, 20 November 2007 (UTC)
- Thing is, Hall effect thrusters also accelerate ions, and are described as ion thrusters but the cathode consists of an electron cloud.WolfKeeper (talk) 05:16, 20 November 2007 (UTC)
- Academic editing of the wikipedia was discussed on the wikien-l list. I think that when an academic assignment involves editing the wikipedia, it's best if the student creates an entirely new article- there are lists of article wanted around. Otherwise you will often find that other users will intermingle their edits, and it becomes harder all round.WolfKeeper (talk) 05:16, 20 November 2007 (UTC)
[edit] References for comparisons
I am interested in knowing about the capabilities of electronic thrusters that are actually in use by satellites, but the table of comparisons between different thrusters is completely uncited, so I don't know whether these numbers refer to actual thrusters or lab tests only. Mattski (talk) 22:45, 22 January 2008 (UTC)
- Dunno. There's a good table in the seventh edition of Sutton with 30 different EP drives in.- (User) WolfKeeper (Talk) 00:05, 23 January 2008 (UTC)
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- I am most concerned about the ones listed with extremely high power consumptions and high thrusts. Of the few commercially produced ion thrusters I could find details on (from QinetiQ and Boeing), they were on the order of less than 200mN of thrust per engine. For example the listed MPDT hydrogen ion engine that uses 7500kW (that's 7.5MW!) and produces 60N of thrust is ludicrous, a satellite would need a huge solar array and power storage bank to power it even for a short amount of time, and I would have a hard time believing it was even built in a lab. The applications of a thruster with those specs would be very questionable since they probably could not be used in space. I believe that citations must be provided to verify the numbers claimed in this table, or they should be removed. They are orders of magnitude different from what sources I have been able to locate, and are thus highly misleading if they are not actually accurate. Mattski (talk) 22:09, 5 February 2008 (UTC)
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- This link from 2003 says that MPDT thrusters have never been run stably above 1MW, I would suppose that they've been run in pulsed mode, but that doesn't make them practical thrusters. I'm considering removing all the MPDT above 1MW, based on this source (i.e. all of them!)- (User) WolfKeeper (Talk) 23:18, 5 February 2008 (UTC)
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[edit] Lorentz Force
I am no expert in ion thruster, and I looked up the article because I wanted to learn about them, but what the article says about the Lorentz force cannot be correct. The lorentz force is perpendicular to the velocity of the particle, and therefore it does not give energy to the particle, it only deviates it. Someone knowledgeable should look at the explanations regarding the use of magnetic fields. In general the Lorentz Force cannot be used to increase the absolute value of the speed of the ions, which is what you want to propel a rocket. I rarely edit wikipedia, but I thought that if someone sees a mistake, he should still point it out even if he can't fix it.... Ivan Biaggio (talk) 02:25, 9 April 2008 (UTC)
- The Lorentz force has two terms, the first term is electrostatic, and does give an increase in speed.- (User) WolfKeeper (Talk) 04:04, 9 April 2008 (UTC)
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- Yes, it is true that sometimes the forces from both magnetic and electric field are combined and that the total is still called Lorentz force. However, the electric term is the Coulomb force F = q E, and the article explicitly tries to distinguish between Coulomb Force and Lorentz Force (Look at the first paragraph!) as two different things that can accellerate the ions. As a result it is confusing. In addition, it is not uncommon in physics to use the term "Lorentz force" more specifically only for the magnetic component.Ivan Biaggio (talk) 23:31, 14 April 2008 (UTC)