That one is actually being used with all commercial flight already....its just a secret...the airplane construction just doesnt fit the needs to carry all that fuel needed for a regular trip.
@@tarassu I bet if one could be exposed to the vacuum of space and one ripped off a good fart that one was holding in for awhile after eating some premium homemade chilli giving that fart a good heavy push lasting for 3 seconds would boost one an estimated 168 miles in just 3 seconds just from natural gas boost!
“A working ion thruster was built by Harold R. Kaufman in 1959 at the NASA Glenn Research Center facilities. It was similar to a gridded electrostatic ion thruster and used mercury for propellant. Suborbital tests were conducted during the 1960s and in 1964, the engine was sent into a suborbital flight aboard the Space Electric Rocket Test 1 (SERT 1).[10][11] It successfully operated for the planned 31 minutes before falling to Earth.[12] This test was followed by an orbital test, SERT-2, in 1970.[13][14]”
Charles Rice my guess is he probably ain’t all knowing and might not be aware that ion engines have been around for that long, especially since I’m only now seeing a good deal of hype about them
@@lemmysverruca But ion drives were not used for *main* propulsion, to provide most of the change in velocity. You are right about their long use in space, but until NASA's Deep Space 1 mission, only very small ion thrusters were used--mostly as North-South station-keeping thrusters on geosynchronous orbit satellites, and occasionally as regular attitude control thrusters. These often-cylindrical ion thrusters were and are tiny, often no larger than a 29 mm or 38 mm hobbyist rocket motor, and only about 150 mm (6") or so long. Also: On many occasions (starting in the late 1960s, when several comets--not Great Comets, but scientifically interesting ones nonetheless--came within space probe range of the Earth), NASA wanted to fly ion drive-powered flyby and/or rendezvous missions to comets. They favored ion propulsion because such spacecraft, despite their often-large velocity change (delta-v) requirements in order to reach their targets, could have been smaller and cheaper, and could have been lofted by cheaper, small-to-moderate size launch vehicles, such as the Delta or Atlas-Centaur, but: The PIs (Principal Investigators--i.e., the chief scientists) of these proposed missions--articles about them are in old "Aviation Week & Space Technology" issues--always vetoed them, saying "You're not going to test an unproved propulsion system on *my* mission!" (or, 'from the other direction,' "I'm not going to spend years of time and millions of dollars developing instruments that will fly aboard an experimental spacecraft whose propulsion system may die [1960s/1970s-vintage ion engines not uncommonly failed early due to power supply, power conditioner, or thruster grid short circuits], long before it generates the necessary change of velocity to reach its target!"), and: Chemical propulsion alternative missions were designed, but they usually required larger, heavier probes, launched by bigger rockets (such as the Titan IIIC, as David S.F. Portree has covered on his space history website: spaceflighthistory.blogspot.com/search?q=comet ). The lower specific impulse levels of chemical propellants made such larger--and more expensive--spacecraft and launch vehicles necessary, and their higher costs, especially in the "budgetarily" lean post-Apollo years (when the Space Shuttle consumed much of NASA's budget allocations, leaving little for Solar System probes), made these chemical-propulsion comet missions financially impossible. To overcome these limitations, NASA "bit the bullet" and in 1998 flew a dedicated engineering test mission, Deep Space 1 (see: en.wikipedia.org/wiki/Deep_Space_1 ), to prove ion drive main propulsion and eleven other promising-but-unproven deep space probe technologies (which are now used operationally)--these were: Solar Electric Propulsion Solar Concentrator Arrays Multi-functional Structure Miniature Integrated Camera and Imaging Spectrometer Ion and Electron Spectrometer Small Deep Space Transponder Ka-Band Solid State Power Amplifier Beacon Monitor Operations Autonomous Remote Agent Low Power Electronics Power Actuation and Switching Module Autonomous Navigation
Ion engines are insane, in both range and time taken. I thought I knew everything about ion thrusters, but I did not know they'd run one for 5 years, or that they had a new design with whole newtons of trust. That's insane
Amazing. I just saw a patent for an ion engine that releases ozone as a byproduct. I wonder if such a system could selectively use pollutants (CO2/Methane?) as fuel and serve as a kind of atmospheric scrubber?
They already have CO2 filters for the air. Some large petrol companies use them at their plants. They are trying to make them profitable by making the by product of the filtration into a compound that can be reused or resold for other purposes.
@@Circaman8 this got me thinking: an idea to clean the environment generally only works thoroughly if it is somehow cheaper to clean and reuse compared to not doing it. The problem with these machines (in the video) seems to me that they cost waaaay more per machine compared to the profit that can be achieved by reusing. However, it is good to consider many possibilities. To make matters worse, a working solution is sometimes used to justify pushing more pollution in the air. The biggest hurdle is obvious. It's our attitude as humans. We have the intelligence to understand that we are causing harm and yet the problem on the whole gets worse partly because we are with so Many and use so much no matter what we have learnt.
This is awesome! I actually design, analyze and build hall effect thrusters for a living. :D I love seeing videos about them, makes me feel like i am making a difference!
Has anybody ever considered that in that galaxy far away people may have some sort of acute synesthesia that makes them hear things when they watch things going too fest? XD
If the earth was heavier, chemical rockets would not be able to get to any decent height. Are civilizations on massive planets doomed to never have nice things?
I beleve all things are relitive. If the gravity was stronger than the chemicals should be more dense ,leading to more energy per volume of a material and should thereatacly be equal. (Just my thought).
Balloons should work better on heavy planets with dense atmospheres and an aerodynamic balloon with correct propulsion should be able to accelerate in to orbit especially if you can propel it using magnetic fields acting against the magnetic field of the planet. This is currently being explored for getting cargo into space from earth and the concept is the most appealing and realistic ways of getting cargo to orbit I have seen.
@@gp849 Density isn't dependant of gravity. YEa you can compress somehting with a hydraulic press, but that won't make it any denser relatively speaking. I mean take toilet paper,press it in many layers. You will still get something that isn't as dense as wood cuz there are tiny air packets in the paper. You can only compress something to the density that of perfect crystal without any space between. COmpress any further and you no longer have the chemical you had. Fucking have a neutron star. That being said. There will be a point for matter where force exerted on it will be just over what it needs to overcome intermolecular repulsion forces and basicly mash atoms together making either a black hole if it's mass is enough or a neutron star.
Maybe not miles but quite big, that's why JIMO looked like a Star Destroyer. Reactor in the nose, bit of shielding behind it and then a couple of hundred square meters of radiators.
I feel dumb. When you said that the space agencies were looking into ways of fueling ion engines with air siphoned from the atmosphere, I thought "what if you could make one that siphons the air that astronauts onboard exhale." Then I immediately realized the very obvious flaw with that :P
Well, in theory the oxygen could be separated from the carbon and gets sent back out for the astronauts to breath but the carbon gets sent to the engine
I love how nasa was like “we don’t wanna put all these risky ideas on something we’ve got going good and messing them up… soooo like just staple all of them to one thing and huck it into space and see how it goes”
Glad you mentioned hall effect thrusters. Those are in use! Not as main engines, but as secondary station-keeping microthrusters for satellites. They like them because they can be turned on and off on a dime, giving them extremely precise control.
I know the major limitation of Ion engines is the low thrust (in Newtons/lb) and that the limit for that is electrical energy. I can't seem to find good numbers on thrust/watt, though - how much power (how powerful a nuclear reactor) would be needed to achieve 1G acceleration from an Ion engine for, say, a Dragon/CST-100 size spacecraft? (~10,000kg)
I know that this is 10 months too late but I've done the calculations for you.. Assuming a specific impulse of 3000 seconds and an efficiency of 70% (which is typical of NASA's small sized ion thrusters), you'd need about 2.061 Giga Watts (GW) of power to propel a 10000 kg spacecraft at 1g initially. Too much power required. Impossible. On the other hand, if you are content with an initial acceleration of 1mm/s^2 or 0.000102g, then you need 210kW of electrical power supplied to the thruster. Assuming you have allocated about 3000kg to the solar panels of the spacecraft, your panels would have to have a specific power of about 70 Watts/kg. Not impossible but extraordinarily challenging. NASA's Dawn probe's panels at 1AU generated about 79 Watts/kg. And panels are getting more efficient and lighter day by day. Another 3000kg would probably go to propellants, 2000kg to structural mass and other subsystems. That'd leave you with a useful cargo carrying capacity of about 2000kg. The total delta V that you'd be able to execute with this configuration is about 10.49 km/s which is about the right value.
Thank you for ending on a hopeful note. There are too many stories of "We had this amazing idea for a solar system mission... but the project was scrapped." The current generation of ion engines use krypton, right? At what rate do they consume fuel? Weeks of constant thrust means weeks of depleting its source of ionizable atoms.
This reminds me of Harlan Ellison, who pursued the realization of Ion Propulsion engines. So glad to see this vid, and thanks for recalling fond memories. 👍
I have been hearing great things about laser based particle accelerators. Could we use these as engines to accelerate spacecraft? It seems like shooting atoms off at relativistic speeds would pack more punch than shooting them off at 90km/s.
The power electronics which create the ions, the magnetic fields to guide the ions, and the electric field to accelerate the ions is a pretty trick achievement.
@@nikolisdex uh no. The DOD runs a secret space program and details of what they're launching into space is for the most part kept under wraps. Their budget and projects are kept secret. They get far more funding that NASA who is ran separately.
An atmospheric ion thruster based satillite would only be able to run about 20 years before the the solar panels began to loose a significant portion of their efficiency, limiting the systems lifetime. So even if parts did not begin to fail, on the basis of solar technology alone, their lifetime would not be indefinite. Awesome video non the less! Great work!!
Actually rocket engines do still look pretty cool , and im only guessing how they mechanically work , and im probably wrong , but it freaks me out to think thrust coming out of exhaust nozzles lift all that weight , the exhaust nozzles must be made of pretty cool stuff . It occured to me that exhaust velocity must have a limit , and once you where in space and just on cruise control on your long journey so too speak, and trying to attain highest speed over a longer period of time , could they narrow the venturi to attain less volume of thrust but more pressure at a higher velocity over a period of time so it works sort of like the ion thrusters ..... in a way using way less fuel ????? no doubt the rocket dudes have experimented with all this stuff , but just a thought anyway .
Yeah, rocket engines really are wonders of engineering when you think about the forces involved. :-) The problem is that exploding rocket fuel has a maximum speed that the exhaust gases can escape. If you narrow it too much, you'll just get the rocket exploding.
Actually if you have had ZERO education about rocket propulsion and you already "get that concept" you should probably be an engineer. Lookup the term "ISP" and then research the VASIMIR engine.
I second Stuart, you've managed to almost accidentally explain some pretty complicated concepts in rocket propulsion there! Maybe look into it a bit more, the more minds we have working in science the better
Hey mikldude, I just watched a video by Curious Droid explaining the issues with designing the nozzle shapes of rocket engines, Scott Manley also has a video on the topic. Basically the idea is that the air pressure at low altitude presses the exhaust closer together, and at low to no atmosphere pressure, the ejected gases expand and make a giant plume of fire that isn't very directed. So nozzles are built with a compromise, kind of like if your car had a single gear and the engineers had to pick which one that would be. There are alternative nozzle designs that have been invented and have existed for a long time called the Aerospike which lets the air pressure form the ideal exhaust shape by itself, however these haven't really been implemented, mostly due to overheating issues and since they would be experimental, companies aren't willing to take the risk of trying new things. I'll link to you two videos you might find interesting. Video by Curious Droid about the Aerospike: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-K4zFefh5T-8.html Video by Scott Manley about rocket engine exhaust nozzles: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-l5l3CHWoHSI.html Hope you'll find these interesting :) keep learning, keep thinking, and keep asking questions!
So theoretically a modern probe could be sent to catch up with Voyager scan the area take photos of Voyager to see it's external condition and continue out beyond sending us back some awesome telemetry.
I remember in grade 12, I wrote a short story based on a song (the other option was based on a poem, but I wasn't big on plain ol' poetry). I turned the song into a sci-fi drama and at one point, actually used the term "ion engine." That was 1994. I'm not certain where I got the idea (I didn't use the internet at that point, much like most people didn't). It's possible I read about them in Astronomy Magazine though..
Ion engines are a surprisingly old idea, even though most practical applications are fairly new. I recall seeing a photograph of an experimental ion engine being tested in a Finnish encyclopedia from the mid 1960's.
The Bepicolumbo mission has the most powerful one ever sent to space, and it's about to turn it on for the first time. Pretty exciting to see these ion engines getting used.
Positively electrifying. I'll keep my ion you for any new shocking space facts now that I know the potential of this channel. My resistance was unjustified, glad to find this outlet of science.
This was a really nice video Fraser, this kind of space stuff is so interesting, could you do the same with other types of 'space' technology? Great work, we appreciate your immensely
I came here not by algorithm, but by search. I had just remembered a video from years ago about sucessfully using ion thrust on a model airplane. Blew my mind seeing something fly around a room without mechanical propulsion.
Space isn’t a perfect void There are atoms, and I can’t remember the exact figure, but it’s like 5 per m^3 Why don’t they look at using these? Would take a very king time, but maybe using gigawatts of electricity may make interplanetary missions feasible or even comparable with current ion engines
Fraser Cain say they’re ions and positively charged, use a negative magnetic field to draw them in, then reverse the field. This could be easily made with current tech. Interuptors and full bridge rectifiers would enable this. The ‘scoop’ could just be a hollow column down the middle of the craft. since the field would draw the atoms in, it would suck in atoms from outside its cross sectional area Powered entirely by solar, however a lot of the weight would be capacitors batteries and the solar panels would need to be massive. The trust to weight would be abysmal, but theoretically it could work. Like current ion engines, it would be measured in 1 1000ths of a Newton, but would be able to function indefinitely since it doesn’t require xenon, or any fuel at all.
I think the problem is that it isn't enough to sustain the engine. Like inetrnal combustion engines can't work at higher altitudes due to thin atmosphere.
Like Neurofied said, there just isnt enough particles. 5300 per cubic meter SOUNDS like a lot, but its barely anything. Even these ion thrusters use orders of magnitude more particles. The dot of the letter i that you write for example, has something on the order of 10^12 atoms in it.
In essence ion thrusters are little different from the first steam engine, that is accelerate a propellant and use it to do some work. This will never cut the mustard if humanity wants to traverse the galaxy.
Well ignoring the hard vacuum and assuming a moderat 2kW thruster it would be very similar to putting you hand in a oven set to a few hundred degrees. Ie it would burn eventually but not right away. can't say I've seen meat behind one but I have seen odd things put behind them. Grad students get bored too. ;)
orbitONhigh Haha, sounds cool. Tell me something, if you have some time: •What is the average number of ions being launched backwards by these things? •Is there any way to control the thrust produced by these engines? If so, how's that done?
I think some guy on youtube put a piece of paper behind a little one and it didn't get burned. Maybe it'd feel like a hair drier at first and just as a hair drier it would dry and heat up your hand until it carbonizes?
well the one I worked with ran at a couple amps and a few hundred volts. Ideally your ions are singly charge ie you knock 1 electron of the atom. So that would work out to roughly 1Q=1A/s =6.2x10^18 so at ~3 amps thats ~1.8x10^19 ions/ second might want to knock off a few hundred quadrillion to efficiency losses though:) thrust is roughly a function of power. More amps means you are throwing more ions, high voltage you are throwing them faster ie accelerating them harder, Newtons old equation give you thrust F=MA, In reality you can't control voltage and current independently of each other though and there are practical limit for any give design on how much power/voltage/current it can handle.
Raising pressure would increase the rate at which ions and electrons recombine to form neutral atoms, and neutral atoms of course cannot be accelerated by an electric or electro-magnetic field ...The limit to how much thrust you can generate is precisely this, that you cannot ionize a gas at high pressure except at the price of extremely high energy consumption. I found odd the video did not mention this.
I do agree ion engines are more efficient, and practical, but the output of energy from a small amount of ion engines just isn't enough to lift, say, a 500 Ton rocket. Not without requiring a massive amount of thrusters. The best thing to do is set up orbital space stations assembled piece by piece, and construct larger ships in zero gravity, then have those ships be propelled by ion engines. It would require more hydrogen fuel to launch the parts into space, sure, but could prove useful for making larger ships. It's just common sense, really.
@@frasercain Love the channel and your videos by the way, I'm an aspiring aerospace engineer myself. What field of work is your career in? Is it space oriented, because judging by your content I'd guess so!
The amount of resources it takes to launch all the parts into orbit individually would be more than the resources to just launch the whole thing in the first place, just doesn't make sense. It's like saying, "Instead of driving straight to the supermarket just drive over the hill and then you use less gas because you go down hill" but it doesn't work because you'll use more gas going uphill
I've designed a radical new drive that uses super hyper compressed gullibility mixed with hyper super fluffed stupidity. Theoretically, the gasses exhaust at light speed, but I haven't got the bugs all worked out of the super hyper fluffer... The fuel supply, though, seems to be inexhaustable.
If I understand correctly, those engines need atmosphere to supply thrust, so how do those engines work in space? In general, I liked it so much, It seems so correct for future space travel.
Ion engines sound cool , but they need to get serious , if i had some curry for tea i could moon out the porthole and fart more thrust :) (might be a bit chilli though ) ..... they need to make them big , make them 10 or 50 metres across , we are not trying to fit them in the car park , we just need more power !!! :) . And maybe im barking up the wrong tree , but instead of wimpy solar panels for power , why not use nucleer power like a submarine power unit or two ???? And maybe if they did power it big , they could afford to make the ship bigger and better equipped ?? Something i should have asked first , (forgive my ignorance ) , what are the properties of the ion thruster exhaust emmisions ? if i stuck my hand in front of the working exhaust would it glow in the dark or would it vaporize ??? Good video and subject by the way , thank you .
Fraser Cain sorry i missed that bit ( forgive me i`m old :( ) , i guess it is easy throw ideas up , but very expensive to pay for them , still ...... exciting times in the space industry . Thanks for your good videos and the replys mate , always interesting . cheers.
Fraser Cain Maybe if BFR gets online they would revive it. NASA should leave orbital stuff to commercial provider's and go for the deep space projects that are more bleeding edge.
Ion beams are also used for coatings like a sapphire coating on your camera they shoot these particles at the desired material and charge the material they want to coat by supplying it with enough energy to attract the positive particles
These are pretty interesting engines, the concept of using them alongside a nuclear reactor for orders of magnitude more thrust is also pretty exciting too. I guess we just have to keep watching this space and see how the ideas evolve. I would expect that over the next decade we will make decent leaps in solar power generation too, which could lead to a safer and much more powerful ion engine than we have access to today.
Yup, and now that NASA announced their kilopower fission reactor, there might be a technology that'll be able to provide the higher levels of electricity to run these engines.
I just did some reading about this kilopower fission reactor, thats some really interesting stuff and the reactor is so small. This is going to enable a lot of different ideas to expand, not just with propulsion but probes and habitats too.
here are some parameters: 1 falcon 9 space dragon capsule - velocity 125,000 ft/s - 20,000,000 dollars 1 test xenon - thrust for 10^7 seconds needed at 100,000 ft-pounds/second - 17,000 pounds of xenon - 100,000 watts for 100 days. This thing starts at earth orbit and somehow gets the 100 days before mars orbit where the solar power is way too low. (r/r)^2 power ratio earth power is 10 percent of 1000 ft pounds / s per square - without trying a low sun orbit ( checks out as maybe unfeasible days ago) interval 1: 90 minute orbit 5400 seconds xenon force is 1 pound velocity change was 6 ft/second . iterations and portions of earth and sun escape velocities added to the 125,000 ft/second
There is something wrong with the ion thruster description, which apparently accumulates a massive negative charge, by expelling only positive ions, and retaining the corresponding electrons. Eventually the huge electrostatic charge would interfere with the thruster performance.
Hi Fraser. I'd like you to do a video on the idea of deep-space exploration using a nuclear energy sourced ion engine. What you've done here is great but it would be bringing it to the next level if you could do a thought mission (or 2, or 3...) to some place like Sedna for example...AND do it with some numbers. For example, starting with some useful satellite mass orbiting Sedna, then moving to the question of how long a nuclear fuelled ion engine would take to get from Earth to the dwarf planet. What size of a chemical rocket would be necessary to lift that payload from the surface of the Earth, accelerate, and then decelerate so as to be able to go into orbit. Now THAT would be an interesting video! It took many years to get to Pluto and Ultima Thule; how quickly could such a journey be done using a nuclear powered ion engine?
Hi there Frasier. Great video about ion drives. Have you looked into Mach Effect thrusters, and the Mega drive at all? I would love to hear what you think of these new drives and if you think they have a future.
Thanks, and just noticed the terrible auto-correct on your name. My apologies. Mega is an acronym for Mach Effect Gravity Assist drive btw, just on the 1% chance you were not aware and needed another search term. :)
Great video. Ion propulsion is only in its infancy. I hope to live long enough to see when the real breakthrough, is when we can figure out how to use lower voltage.
The air-breathing ion engine is quite amazing, especially considering it's already proven by test firing in the lab and doesn't have any game-breaking technical problems to overcome. That being said, it probably won't be usable by the ISS since the atmospheric density is not high enough at 400km orbit. On the other hand, the ISS was put on that orbit because station keeping was too prohibitive at lower altitudes as it is easier to launch astronauts and supplies to lower orbits.
. During the Shuttle days, ISS was orbited at 320kms approx. The lower altitude aided cargo capacity to the high inclination ISS orbit. The Shuttle reboosts and the great capacity for propellant the Shuttle could deliver, would offset the increased atmospheric drag the lower altitude created. Since Shuttle retired, the more efficient over 400 km altitude was selected.
Amazing video.....I just thought that by using the chemical engines spacecrafts only till the earth's border Atmosphere and then separating the ion engine satelite in the separation stages.....it would certainly save a lot of power and fuel and give high efficiency results....... 👍👍
So if i can say perhaps, eject the atoms out even faster and send out more of em at a time i can make it more powerful? What about finding some way of ejecting them out of a nozzel like thing. Cuz i know with alot of things you can get alot more force out of ejecting a substance if its concentrated amd directed a certain way instead of every wich direction. At my job (keep in mind i know these things arent exactly the same) we have a hose or whatever jus a regular waterhose and we got a thing on it where we can change the way the watet comes out. And i noticed you get alot more force if you concentrate the water into a jet than if it was jus out and flying about in the general direction of whrte your pointing.
If you click on my channel icon to the left, you can see many prototypes of my ion thrusters lift their onboard power supplies against earths gravity. This is the first and only heavier than air ion propelled aircraft that can lift its power supply without external assistance. Under the videos there is a link to the website also. There was some news claiming MIT made an ionic glider that was the first to carry its power supply but, if you look into it fully you will see that in this rare instance, they were not first. The patented ion thruster on my site could carry a small propellant tank, so it should work in a vacuum, though it still needs to be tested for that. Imagine accelerating for long periods of time at greater than 1G. Even at a small fraction of that it would open up exciting possibilities!
With no atmosphere no drag, Wouldn’t need propulsion once set in motion. So there is something that smells rotten here. The thrust would only have to be till craft is up to speed. Then you’ll need reverse or side thrust to stop or change direction.
Newton’s third law would dictate the ship in 0 gravity (Note the space station has micro-gravity), would continue forever without propulsion without need for more fuel after it is up to speed. So you would need very little fuel. The thrust gas would also go in the opposite direction forever or until it meets something else. And the next fuel or thrust would be needed to stop.
At least people now are accustomed and expects tech to improve rapidly. A thousand years ago, nothing would change for generations, and no-one would ever dream of change of technology.
Mosern1977 I don’t think it will improve rapidly. We have accomplished the low hanging fruit so far. Everything moving forward will be more complex and harder to make. Computing tech for example hasn’t changed just been optimized. This is the first engine design I’ve heard with actual development that has a complete new design for propulsion.
I saw an article recently about a scientist who was able to use ion thrusters to propel a small plane a short distance even at earth's atmosphere and gravity. One step closer.
Like, to clean up the space junk? Sure, an airbreathing engine would be a very efficient way to clean up the junk, except anything at that altitude is already going to be de-orbiting soon anyway.
well I mean 1. lower orbits become more useful with that and everything we send there won't contribute to our space junk problem. Anything we loose control over there will deorbit itself. 2. Yea If they get good enough that they can refuel some air tank, we could have satellites that go to a higher orbit grab a peace of space junk and bring it back to their refueling orbit. or the could go on an elliptic orbit and aim the Ion thruster at the debris, to slowly lower it down. Both would take an awful lot of time, but I think, that is ok.
The formula for kinetic energy is 1/2mass*velocity^2. Doubling the exit velocity will quadruple the kick. Couple with with the rocket equation, where the more fuel you have, the more fuel you have to accelerate. Increasing the exhaust velocity and dropping the mass of fuel makes it very worth while.
Yes, but the issue isn't how much energy we can get, it's how much mass we have to accelerate. A chemical rocket might have 10x the energy, but it also has to accelerate 100x the mass. It's a net loss of delta-v
