Plasma Rocket Engine

[plasmahunt3r]

My goal is to build a Plasma Rocket Engine and I am posting here to share results as I learn and to share information with other experimenters.

****** Warning ******
This project is experimental and the circuits contain LETHAL amounts of Electrical Current. Also, UV light is created which may permanently damage your eyes. Please do not attempt to replicate without proper safety precautions. I am not responsible for any injury or death that may result from your own experiments.
*******************

A Plasma Rocket Engine is different from an ION engine. A Plasma Rocket Engine uses plasma energy to heat up a gas (or vaporize a solid) and electrically propel that gas out of the engine. It is basically an electric engine. It has many other uses, such as burning waste or purifying water.

A solid fuel commonly used on Pulse Plasma Thrusters is Conductive Teflon. Teflon vaporizes at a low temperature. The teflon is vaporized, electrically charged by a spark plug, and accelerated via a rail gun setup to create thrust.

There are two main methods to create the plasma. One is to use a high current to create a hot plasma. The other is to use RF in 2-50 MHZ range to heat up a gas (similar to Magnetic Induction Heating).

I am starting with high current to create my plasma. The first challenge was to create a high Current Plasma Arc by tying together High Voltage with a High Current Capacitor Discharge. The three Plasma Arc Circuits I am attaching is how I accomplish this.

The first circuit showed how to obtain 3 electrodes by using a 50KV isolation capacitor.

The second circuit expanded on the first circuit by splitting the Neutral Electrode in two (by wire) and adding a Capacitor Discharge Circuit. This worked.

The third circuit expanded on the second by adding an air core isolation transformer along with the Capacitor Discharge Circuit. This worked too.


**** Test Result *****
Capacitor Discharge Circuits were dissapointing. They worked but I only get a pulse. To be really useful, I need a continous Plasma Stream.


**** Test Result ****
I got Continous Plasma by modifying the third circuit. By dropping the capacitor discharge circuit and directly connecting the AC to the air core isolation transformer, I get a Continous Plasma Discharge.

I still use the 50KV capacitor to drive the isolation transformer, but instead of merging the arc with the discharge capacitors, I directly connect the transformer to same AC source. Now I get to add the AC Current to the HV arc. WOW!!!!! The AC current I use is limited by the AC start Capacitor.


**** Update ****


What is really of significant importance, is the current limiting 30Uf AC Start Capacitor. This AC capacitor can be placed before (or after) the light dimmer switch. Wherever it is placed, it limits the current to the circuit by Capacitor Reactance.

Capacitor Reactance = 1 / ( 2 * Pi * Frequency * Uf / 1000000)

So a 30 Uf cap on a 60Hz circuit would be:
1 / (2 * 3.14 * 60 * 30 / 1000000) = 88.46

120Vac / 88.46 = 1.366 Amps.

So the 30 UF circuit limits the current to the coil and Plasma Arc to 1.366 Amps.

I had limited myself to a 30Uf capacitor, because, when I used larger caps, I blew out my ignition coil. But since I am now splitting my circuit between the Ignition Coil AND the Plasma ARC, I think I can upgrade to a larger value Current Limiting Start Cap. The limiting factor is now the 600 Watt light dimmer. I think I can pick a larger start cap and go as much as 4 Amps, unless I upgrade to a 1000 watt dimmer.


*** UPDATE ***

I changed to a 108Uf Start cap which puts the circuit at nearly 5 amps. The result was a larger plasma ball and burning sparks coming off the electrodes. More current = more powerful (and hotter) plasma.

[Jeff Pearson]

coooool, this plasma thing has lots of tangents!!!

[mikrovolt]

The drawings found in pdf called plasma reformer.
developed at MIT called plasmatron then government tested.
The MIT people sold out. one company in oregon called Umpqua
put out a few pictures and diagrams. Umpqua claims 30% increase fuel economy and emissions are very low.

[plasmahunt3r]

Added Snubber

I rebuilt my board using the 108Uf AC Start Capacitor to limit the current to 5 Amps. Turns out 5 Amps is powerful enough to erode electrodes and burn anything close through radiating heat.

I am updating my circuit to include a snubber on the coil to absorb spikes.

The attached are the new circuit and a picture of the 5 Amp board.

[plasmahunt3r]

Replaced Dimmer Circuit

I pushed the circuit to the limit and burnt up the dimmer switch.

I found that I can replace the dimmer switch with a TRIAC based pulse circuit.

The TRIAC (NTE5646) is 10 Amp capable and has a built in Internal Trigger DIAC which simplifies the circuit. That plus an on/off switch, a 100K resistor, and a .1 UF 250V capacitor is all that is needed to have a solid state pulse circuit for an Ignition Coil.

The attached schematic shows how to hookup the TRIAC based pulse circuit.

*** Update ***

Tried different RC values for TRIAC to see which gave the smoothest spark gap. I didn't feel like updating the schematic. Got the smoothest result with 100k and .039UF 200v timing cap. Could use 39k & .1UF to get the same math result:

1T = 1000000 * .039 / 1000000 = .0039 Seconds Or:
1T = 39000 * .1 / 1000000 = .0039 Seconds

*** Update ***

I did some more testing, using different ignition coil and different AC start capacitor (To limit current). I found that the RC values used with the TRIAC are dependent of the coil and current provided by the AC start capacitor. Switching coils types and increasing current required different values for the capacitor and resistor used for the TRIAC gate timing. Too high of a resistor and it won't turn on. Too low of a capacitor and it won't turn on. You will have to test different values and decide on the right combination for your hardware.

If you increase the current available (larger value AC start Capacitor), then you need to slow the RC timer by increasing the values of the resistor and/or capacitor.

[wayne.ct]

Tell me more

This plasma generator seems to be very different from the spark gaps typical in this forum. Would someone like to explain and elaborate on this DANGEROUS circuitry?

[plasmahunt3r]

Dangerous Plasma

This is serious stuff and is no way a toy.

This circuitry is closer to a plasma torch or a plasma welder. Depending on current, the plasma can produce thousands of degrees of heat. It can cut through steel and can crack molecules into their individual elements. That is why it can be used to decompose hazardous waste into safe elements like carbon, nitrogen, etc.

The higher the current, the more heat is generated. I limited myself to 5 amps for testing and that is hot enough. I used to have my plasma electrodes on wood, but the heat radiated, set the wood on fire. I am building a new ceramic base for the plasma electrodes.

Also current kills, so safety when testing is critical. I put on rubber gloves every time I test.

My goal is to build a plasma rocket engine and I know there are other experimenters out there interested in the same stuff. The circuits are not mine, although I modified them as a result of my testing.

Look at this site for a description on Electric Plasma Engine: My Electric Engine - Main

Look at this site for a description on a HV start box for a welder circuit: High-Frequency Start Box

Both these sites form the basis of my circuits.

I am not inventing anything new. MPD thrusters are currently on satelites. I am just learning how it is done.

[wayne.ct]

How much thrust have you been able to document?

Thanks for the two references. That helped to round out my knowledge of the technology. Can you provide links to any videos of your experiments?

[plasmahunt3r]

No Video Yet

I don't know how to post video's yet. Suppose that is something I have to learn.

I am not planning on taking any video's until after I link the plasma with a pressurized gas and have achieved at least a Plasma ARC JET Thruster. I cannot forecast a date. There is a lot of research, testing, and construction to do before I get to that point. I am planning on spending 3 years and up to $10,000 on this project .

I can find pictures of thrusters, but actual construction details are elusive. There are a million details that I have to figure out. There is no "How-to" on building this. By the time I finish, this should become a how-to.

Part of this is the Power Electronics to produce plasma. Now that I have plasma, how much power do I need?

Part of this is Hardware Machining for the thruster, where the plasma arc and gas will come together.

Part of this is Materials Science, like coming up with ceramic electrical insulators or using metals as a fuel.

I have bought a lathe and can do some minor machining. I am running into some insulation issues when putting a metal electrode into a brass "T" fitting. I tried portland cement as an insulator, but portland cement is electrically conductive (about 27M ohms), and the arc jumped through the portland cement. Not where I wanted the arc. I tried a castable alumina ceramic but it is brittle and cannot handle 1800 psi pressure. Could use some ceramic help. I need a high pressure high voltage electrical insulator. A design change could mitigate lower strength materials.

Rignt now, too many problems to solve. If someone out there is working on electrical thruster hardware issues, I would sure like to know what you are doing.

[IndianaBoys]

I tried portland cement as an insulator, but portland cement is electrically conductive (about 27M ohms), and the arc jumped through the portland cement. Not where I wanted the arc. I tried a castable alumina ceramic but it is brittle and cannot handle 1800 psi pressure. Could use some ceramic help. I need a high pressure high voltage electrical insulator. A design change could mitigate lower strength materials.

Hi Plasmahunt3r,

You could give Grancrete a whirl:
http://www.energeticforum.com/renewa...tml#post202645

IndianaBoys

[Reiyuki]

1500psi? Maybe you should look at using multiple layers or a laminate, one layer for strength the other for dielectric. Concrete gathers its strength from compressive loads and not pressure-bearing ones; a concrete block could become a frag bomb.

smooth-on has a decent selection of epoxy putties,coatings, and sprays.


How about using an old small welding gas tank? Coat the inside in several layers of high-temp dielectric epoxy, then perhaps a coat of grill/muffler paint on top of that to smooth things out. Then you could get a high-pressure, high-temp, high-voltage seal to the inside by drilling+tapping a spark plug into one or more sides.

[plasmahunt3r]

Materials Science

Aluminum as a possible fuel for a Plasma Rocket:

From DR Goldschmidt, Inventor of Thermite:

Doctor Goldschmidt ........ knew that aluminum has a great affinity for
oxygen, or, in other words, .......... aluminum wants oxygen more than any other metal does.

So, if I understand this right: If I push enough current in a plasma arc, and heat an aluminum electrode to a sufficient vaporiziation point, in the presense of an oxidizing agent, reduction should occur, where aluminum will rob the oxygen from the other substance.

The oxidizing agent just has to contain oxygen for reduction to occur. In thermite, Iron oxide is the oxidization agent, but other oxygen bearing substances could be used. This means, that at a certain temperature, CO2 could be used as an oxidizing agent, and aluminum would rob the oxygen from the CO2.

In this case, the Plasma would be the initiator, and Aluminum/CO2 combustion would be closer to a normal rocket engine. The Plasma ARC may be required to sustain the Aluminum/CO2 combustion process. Combustion might cease once the Plasma Arc is terminated.

[plasmahunt3r]

Plasma Arc

I made a ceramic block for the electrodes out of portland cement and kaolin clay and had a local ceramic shop fire it for me. I had to abandon wood because it kept catching on fire.

I hope you can access photobucket ok. I put a picture there of the white plasma arc because I have reached my photo limit on this site. It is hard to capture, but in addition to the white plasma light, I also get a few sparks flying off the aluminum electrodes.

Plasma-White-ARC_zpsef3e8cd3.jpg Photo by plasmahunt3r | Photobucket

[plasmahunt3r]

DC Plasma ARC - 5 Amp

I converted the PLASMA Arc from AC to DC using the dimmer replacement circuit with a Quadrac (TRIAC w/internal DIAC) and adding a full wave bridge.

Circuit posted at photobucket:

DC Plasma ARC Circuit Photo by plasmahunt3r | Photobucket

*** Update ***

Ran some test with DC Plasma vs AC Plasma. The AC plasma looks more like a bright white cloud. I guess this is because the polarity is reversing 60 times a second. The DC plasma puts out the bright white light, but is more condensed to the diameter of the electrodes. I guess that this is because the electrons are flowing from negative to positive direction.

[plasmahunt3r]

Plasma Magnetic Containment

*** Magnetic Containment Question - need help???? ***

In NASA studies regarding plasma rocket engines (VASIMR), they indicated the heated plasma will be contained in a magnetic field. I don't understand how this works.

When I put neodymium magnets close to the plasma, the plasma is attracted to the magnet and the plasma moves towards the magnet. This occurs on either magnet polarity. So, if my test show that Plasma is attracted to a magnetic field, how can they contain the plasma in a magnetic field? I am confused. My test results don't jive with NASA's presentations. Is there a trick to accomplish magnetic containment of plasma? I know they are using superconductor magnets, but the magnetic reaction should be the same.