plasma engine

[bl4ster]

is it possible to make plasma jet engine or even plasma PD engine?

[CaptainPanic]

The whole point of a jet engine is that it sucks in air, compresses it and then mixes that air with fuel, and ignites it.

 

All the plasma engines that wikipedia mentions are rocket engines (i.e. no air involved).

 

You can't have a jet engine without air - for the simple reason that it wouldn't be called a jet engine anymore.

 

And regarding the PD engine: Google suggests that those are specific types of diesel engines. Not sure how you would want to convert an internal combustion engine into a plasma engine/rocket.

[Realitycheck]

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Edited May 4, 2011 by Realitycheck

[bl4ster]

PD stands for pulse detonating(the whole word is Pulse detonating wave engine)

I was thinking of an engine like jet engine but instead of regural fuel you put plasma gas in the chamber and start the reaction with electrick arch(which would be at the end of the jet pipe) which creates super heated plasma and then you blow the air in which throws the plasma out,same principal as jet engine,but you would have chambers in circle and they would go(make explosions) one after another.With 12 chambers it can probably reach 200 hz and maybe even more.Design is based on plasma torches.

 

 

[Newbies_Kid]

good idea, but can the engine withstand the heat from super heated plasma? To create a huge thrust i believe we need to heat the plasma to some million kelvin isn't it. Plasma has less mass compared to hot air.. hence produce less thrust. Rocket move in zero gravity space, so using plasma should be no problem.. but for a jet which already have a tonne weight, this is the major drawback isn't it?

[CaptainPanic]

Ah, I understand now.

 

So, if you mean to have something like a plasma cutter (plasma torch), then you can have an electric jet engine. There are (many) practical problems, but thermodynamically (i.e. theoretically) I think it'll work.

 

Plasma engines in spacecraft actually accelerate the gas using an electric field, or a magnetic field. A jet engine however accelerates the gas because the temperature goes up, and there is a pressure difference between the combustion chamber (high pressure) and the back end of the jet engine (outside pressure).

 

But it can work. You can heat the gas in the "combustion" chamber electrically, so that there is no actual combustion. Theoretically, you don't even need a fuel. Just ordinary air would work.

The US once tried to do this with a nuclear powered ramjet instead of an electricity powered jet engine... but the plan was scrapped after testing.

[bl4ster]

Plasma engines in spacecraft actually accelerate the gas using an electric field, or a magnetic field. A jet engine however accelerates the gas because the temperature goes up, and there is a pressure difference between the combustion chamber (high pressure) and the back end of the jet engine (outside pressure).

 

When gas goes thru electrick arch it heats up to about 20000 celzius.So its same principal as jet engine but diffrend heating method.The only problem is that plasma torches are used for cuting jet engine parts cause they can make greater temperatures.

[CaptainPanic]

When gas goes thru electrick arch it heats up to about 20000 celzius.So its same principal as jet engine but diffrend heating method.The only problem is that plasma torches are used for cuting jet engine parts cause they can make greater temperatures.

You can always choose to use more heat, or less electricity, to achieve lower temperatures.

But the efficiency of the engine goes up with higher temperature, so make sure to get it as higher as possible without melting the engine.

 

I think a much bigger problem is how you're gonna get enough electricity to get the engine running. Batteries? It needs to be very light if it is fitted in an airplane / spacecraft.

[bl4ster]

Inverter plasma cutters

 

Analog plasma cutters, typically requiring more than 2 kilowatts, use a heavy mains-frequency transformer. Inverter plasma cutters rectify the mains supply to DC, which is fed into a high-frequency transistor inverter between 10 kHz to about 200 kHz. Higher switching frequencies give greater efficiencies in the transformer, allowing its size and weight to be reduced.

Edited May 5, 2011 by bl4ster

[Sneemaster]

Finally someone thinking along the same lines as me! An air-breathing Plasma engine would save a lot of propellant since you don't need to "Burn" fuel. You could use microwaves (like the Vasimr Plasma engine) to heat the incoming air to a high temperature plasma and magnets to aim the exhaust as well as keep it from frying the rest of the aircraft. You could use a large Fuel-cell system to power it all (probably Hydrogen-Oxygen or something) or later a Fusion reaction (like the Polywell Fusion reactor) . Other options could be laser plasma heating or even a nuclear reactor.

 

The benefit of plasma is that you would have no moving parts, especially if you have a ramjet intake instead of a turbofan intake! The magnets would do all the work so less maintenance to worry about. Plasma exhaust would also be much hotter, so you'd get a higher specific impulse combined with the huge amount of mass from the air would give a large thrust and incredible speed (if you could heat enough of it fast enough) at very high efficiency. Imagine the power of the space shuttle but in a craft the size of a private jet.

 

You could even create a small plasma field outside the ship controlled by magnets to keep the superheated air from causing friction and heat on the aircraft while it's flying. That could also be used to reduce re-entry heating as well so you wouldn't have to have tons of heat shield tiles like the space shuttle does.

 

If you carried a little extra propellant onboard then you even could travel into space and back.

 

Just a thought...

[bl4ster]

you just wrote what i was thinking about

I also started working on plasma field.It works but you just need a lot of electricity

[CaptainPanic]

Inverter plasma cutters

 

Analog plasma cutters, typically requiring more than 2 kilowatts, use a heavy mains-frequency transformer. Inverter plasma cutters rectify the mains supply to DC, which is fed into a high-frequency transistor inverter between 10 kHz to about 200 kHz. Higher switching frequencies give greater efficiencies in the transformer, allowing its size and weight to be reduced.

2 kW equals about 2.7 horsepowers. Even ultralight aircraft usually have at least 15-20 hp (5-8 times as much!!). So, even for a small, single-person aircraft you need 5-8 plasma cutters for power. If you want a real aircraft, with real speeds, you're probably looking at 10 times as much.

 

I'm not saying it cannot be done. I am only saying that you shouldn't underestimate the amount of power required for flight. And you will need really light batteries.

 

Sneemaster, I really don't think that an electric engine and 'a little extra propellant' will get you into space. Please do some calculations. They say space starts at 100 km (already hard to achieve). But to achieve orbit, you need 200 km, and (the most important) a velocity of 8000 m/s (!!!). That's why rockets are so freaking huge.

[the asinine cretin]

Anyone know if the VASIMR is really legit? I hear they are supposed to put VASIMR thrusters on the ISS in the near future. On the other hand, I can remember Robert Zubrin vehemently trashing the VASIMR and basically saying it's a scam. I can recall a PBS show that spent ten minutes talking about the VASIMR and thought it was a load of crap. As if the only options are the VASIMR or a ridiculously long chemical rocket journey. If my impressions are correct it was very skewed pro-VASIMR propaganda with Neil deGrasse Tyson as the host.

 

P.S. Here is the Zubrin screed I was thinking of. The VASIMR Hoax