Low temperature plasma

RobertDyck · 2023-12-01 14:22:44

I found a website that sells equipment to produce low temperature plasma, below 50°C. It thermalizes electrons, not the rest of the atoms. A handheld device uses AC between 24 and 12 volts @ 50kHz to excite a ceramic transformer. The solid piezoelectric ceramic produces 20k volts. The high voltage AC produces plasma from air, or atmospheric pressure gas.

This has a few applications. Relyon Plasma, a division of TDK, produces devices for removing paint, applying varnish, adhesion, or sterilizing medical instruments. But I'm thinking bigger.

Could a cold plasma be held between electrostatic bars, creating a forcefield like the one for brig of Star Trek? In high school, a physics demonstration showed a Van de Graaff generator. When operating, if you try to touch it, a discharge will shock you and charge you, then like charges repel pushing you back hard. This would require power, a simple locked steel door would make more sense, but would be interesting to make one.

A more useful application would be an aircraft thruster. One sci-fi book described a ring on either side of the aircraft. The ring glowed blue, and thrust air down. This allowed the aircraft to hover like a helicopter or jump jet. No spinning blades. The story warned bystanders to not get too close; air flow could rip your arm off. Could cold plasma be moved by electrostatic force? Something like a HAL thruster, but for air? Would this be safer in an urban area within an enclosed area, such as towers of Manhattan?

RobertDyck · 2023-12-01 14:32:03

I posted elsewhere about a forcefield to contain air against hard vacuum. Plasma window will hold in up to 1.5 atmospheres pressure against hard vacuum, but requires a viscous plasma. That can be formed from air at 12,000°K. If anything touches the plasma it could easily cool below the 12k°K critical temperature, so researchers now use 14k°K. That's insanely hot, will incinerate organic matter like your hand, or melt metal including steel, titanium, even inconel. And it requires 20,000 watts per inch diameter. I said to reduce radiant heat so it doesn't broil you, and to reduce power required, layer plasma with something colder. Could a cold plasma form a layer over the hot plasma? What gas would be opaque to radiant heat from the hot plasma?

RobertDyck · 2023-12-01 14:37:50

Personal shield. The books Dune and Foundation included a personal shield that can stop fast moving objects such as bullets. A fast moving knife blade such as a thrown knife would also be blocked, but a slow knife could get through. How would you do that with a cold plasma?

tahanson43206 · 2023-12-01 15:38:13

For RobertDyck re new topic ....

Best wishes for success with this new venture!

You've set the stage for what could become an in depth study of physics in general, and plasma physics in particular.

The forum archive shows that in the past, we have had member/contributors who could have (and probably would have) joined with you to advance this topic in sensible directions. To the best of my knowledge, while we still have members with deep knowledge in a variety of disciplines, we do not currently have anyone who can work with this topic.

We ** do ** have thousands of currently unused ID's, recovered from the spammers whose automated script's created them over 20 years. The Admins are ready and willing to admit new members who might be interested in diving deep into plasma physics with RobertDyck.

See the recruiting topic for procedure.

All we need is ** one ** person to give this new topic a chance to shine.

(th)

Calliban · 2023-12-03 08:15:09

The problem is that first ionisation energy for nitrogen (which is 80% of air) is about 1.4MJ per mole.
https://chemguide.co.uk/atoms/properties/ies.html

And a mole is just 28 grams. So we are talking 50MJ/kg. And that is just first ionisation. And the gas has to be ionised before it will respond to an electric or magnetic field. This is why Star Trek style force fields would be an inefficient way of containing anything. Even if there are ways of making it work, it will end up being more energy intensive than passive steel bars.

The same is true of propulsion. You must first ionise the air (which costs a lot of energy) and then accelerate it magnetodynamically. A propellor just adds kinetic energy to the gas molecules without investing energy into stipping off electrons. So it will always be more energy efficient. If you are sailing through a layer of air that already contains charged ions (i.e the ionosphere), the situation begins to look different, as the ionisation if provided for free by the sun. Maybe an ionic reaction engine could be useful for station keeping in this sort of environment?

Another idea comes to mind. If we have a planet like Mars, with a thin atmosphere and low gravity, could we build towers between the surface and the ionosphere and harvest the voltage gradient of the atmosphere? We have a naturally conducting region full of plasma, which interacts with the solar wind. So a tower shoukd be able to tap this energy and generate useful power.

This is interesting.
https://mars.nasa.gov/news/8680/maven-m … eric-loss/

Last edited by Calliban (2023-12-03 08:36:40)

Calliban · 2023-12-03 08:48:32

RobertDyck wrote:

Personal shield. The books Dune and Foundation included a personal shield that can stop fast moving objects such as bullets. A fast moving knife blade such as a thrown knife would also be blocked, but a slow knife could get through. How would you do that with a cold plasma?

To stop bullets or blades, you would be better off with some kind of tough fibre based armour. But this is usually cumbersome and uncomfortable to wear. There may be a commercial opportunity to develop clothing that will protect people from knife or pistol bullets, whilst remaining flexible and insulative. The two functions are somewhat contradictory. But you could emphasise survivability rather than invulnerability. Most pistol bullets used in America tend to be hollow point dumb dumb bullets. These produce horrible external injuries, but would be easier to protect against, as they tend to flatten on impact. Maybe we could develop garments that would prevent penetration at the expense of local bruising or broken ribs. People may be interested in compromises between protection and comfort so long as attacks are made survivable.

As an electronic solution: How about a non-conducting piece of clothing with threads of conducting wire in the outer fabric? These are connected to electrolytic capacitors. Anyone attempting any unwanted physical contact will get a shock. The only problem is the person most likely to get shocked is the person wearing it :-) We could have proximity sensors that connect the charge if they detect a fast moving object like a fist or hand heading towards the wearer. A knife blade is highly conducting. Anyone attempting to stab the wearer would get shocked if the blade connects the phases. They would likely drop the blade if that happens.

You could make the entire garment conducting and charge it up like a Van DeGraf generator. But the person wearing it would get shocked along with the asaillant. A Tazer is an easier idea. Or something like a cattle prod. A stick that you carry with you with capacitors within it. If you press the end of the stick hard against an individual, two pins wouod extend on a spring. Each pin woukd be a positive or minus phase. Good for crowd control. Unlikely to be lethal. It would disorient an individual for at least several seconds and would put them on the ground. Long enough to make a swift escape out of a dangerous situation. And the stick would be heavy enough to clout them with as well.

Last edited by Calliban (2023-12-03 09:05:39)

RobertDyck · 2023-12-03 23:07:14

Interesting ideas. Thank you for responding. Here in Canada, hand guns are highly restricted. Most criminals who rob a convenience store or house break-and-enter or car jacking, just use a knife. My grandmother asked my father to teach me to hunt gophers when I was about 10 years old. My grandparents' wheat field was infested. It was a "chore" to go out into the field every day to kill gophers. Give a 10-year-old a rifle and ask him to shoot things? You don't have to ask twice. My father also showed me how to set leg-hild traps. Those traps didn't just hold a gopher's let, the trap usually closed across the gopher's rib cage, killing it. Rifle was .22 caliber bolt action single-shot with steel sights. That is sometimes called a squirrel rifle; science name for gophers is Richardson Ground Squirrel. It is a squirrel, just with a very short tail. Ammunition was .22 short, but .22 long with hollow point was available. Relatives would hang empty pop cans on a barb-wire fence for target shooting. At that time Canada still used steel pop cans. My brother was one year younger, he insisted on using long hollow point ammunition for target shooting. Hollow point is also called mushroom head. It produced a small entry hole the size of a .22 bullet, but exit hole was large and jagged. Just 4 shots and the can is torn apart so much it's useless for target shooting.

RobertDyck · 2023-12-03 23:08:40

Although hand guns are very rarely used by criminals in Canada, they are used. A shield against hand guns and knives would be useful. Even if it doesn't work for high calibre rifles.

Of course legal stuff is even more important. I said back in the 1990s that a Taser would be perfect for self-defense. I understand why you don't want everyone carrying a lethal weapon, what if you make a mistake and shoot the wrong person? But police lobbied the government to make them illegal. Now I've learned personal body armour is illegal in this province. What!?! How can body armour harm someone else?

Creating a personal force field may be difficult. Boeing developed one for tanks and Hummers. An explosive pushed a tank shell away last second.

NewMarsMember · 2023-12-04 07:20:53

This is a follow up on Calliban's post #5

The Earth has a region of dense (relative terms) ionized material ... the Van Allen belt.

In general, the Van Allen Belt seems to have a negative press because of the radiation found there. I'm wondering if Calliban's suggestion might prove useful for a specially designed space craft?

The reaction mass for orbital changes, and especially plane changes, might be readily available. I'm wondering if this might be useful for applications such as debris removal?

(th)

Calliban · 2023-12-04 12:45:28

RobertDyck wrote:

Although hand guns are very rarely used by criminals in Canada, they are used. A shield against hand guns and knives would be useful. Even if it doesn't work for high calibre rifles.
Of course legal stuff is even more important. I said back in the 1990s that a Taser would be perfect for self-defense. I understand why you don't want everyone carrying a lethal weapon, what if you make a mistake and shoot the wrong person? But police lobbied the government to make them illegal. Now I've learned personal body armour is illegal in this province. What!?! How can body armour harm someone else?
Creating a personal force field may be difficult. Boeing developed one for tanks and Hummers. An explosive pushed a tank shell away last second.

When the state criminalises wearing *body armour* you know the state is rotten and not on your side. There is no technological solution to a problem that stems from bad government. And is clear that the government in Canada has gone bad in every way.

Last edited by Calliban (2023-12-04 12:48:29)

RobertDyck · 2023-12-09 19:57:43

YouTube: I built an IONIC PLASMA THRUSTER (Best Design)

YouTube: The Next Generation of Ionic Plasma Thrusters (BSI MARK 2)

These home hobby examples are weak, but measurable. Would be interesting to measure performance characteristics: voltage, current, cathode point size, number of points, distance between points, distance from cathode to anode, etc. could we optimize, and quantitatively compare to a ducted fan?

kbd512 · 2023-12-10 04:58:27

RobertDyck,

Your government doesn't want you to even be able to shield yourself when they want to murder you, never mind fight back against their savagery. That is the true purpose behind these so-called "gun control" schemes. They want to convince you to voluntarily disarm yourself, to render yourself helpless, so that they or their proxies can murder you at their leisure at a later date. You can only pretend for so long that someone else has your best interests at heart. The people who don't even want you to have the possibility of shielding yourself from murderers definitely don't have your best interests in mind when they concoct such laws.

Unless your government recently passed laws against owning glue, welding blankets, milk jugs, or bathroom tiles, what they think of you owning body armor is irrelevant. Since you watch YouTube videos, you could easily watch a few more to save yourself quite a bit of money over store-bought body armor. The welding blanket composite was most impressive for its ability to defeat handgun bullets, buckshot, and shotgun slugs. It made a normal IIIA vest look ridiculously overpriced and only modestly fit for purpose in terms of ballistic performance.

How to Make AMAZING Bullet Resistant Armor for $30

Nylon and HDPE composite armor!

Stopping RIFLE ROUNDS with recycled milk jug plates!

The kid in the first video had a rather cavalier approach to respiratory protection. If you value your lungs, more appropriate respiratory protection should be high on your priority list.

I'm not sure what to say about force fields and whatnot. That's a completely different level of tech, and will probably cost a pretty penny to develop.

Calliban · 2023-12-13 11:47:46

Back to the topic of low temperature plasma. With the advent of efficient fibre lasers, we may have a new potential propulsion system for the large interplanetary ship. This is a modified version of the arcjet, in which a laser is used to generate a plasma. This allows greater flexibility in the use of propellants, including junk material like regolith from the Martian moons. The propulsion concept works like this.

We inject a small pellet of material into a chamber. Lasers heat the material to about 10,000K. At this temperature, electrons escape from the plasma and are capture by the chamber walls, which are positively charged. The plasma then accelerates towards the negatively charged exit nozzle, where it recombines with electrons and is ejected from the spacecraft at a net speeds of several tens of km/s. This is a pulsed plasma thruster, that can use any solid material as propellant.

The materials we will be using as propellant are composed of solid oxides. The plasma will therefore contain oxygen ions that will gradually erode the exit nozzle. We will manage this problem by making the exit nozzle out of something cheap and expendable like metallic iron, which can be made on Mars. The propellant pellets will most likely be fine regolith from the Martian moons, which is bound together with an adhesive matrix like polyethylene, which can also be manufactured on Mars. Likely, pellets will be made by compressing regolith into a mould and then vapoyr depositing polethylene to provide a thin package that holds the pellet together for storage and injection.

An electric thruster capable of using any solid as propellant allows mission flexibility. A large ship with a pulsed plasma drive could carry passengers to Mars, any target within the asteroud belt, NEA population or even out to the Jupiter trojans. The effective specific impulse can be relaxed, as all potential destinations have abundant rock and dust that can serve as propellant.

Last edited by Calliban (2023-12-13 11:54:43)

tahanson43206 · 2023-12-13 12:20:47

For Callibam re #13

Is there a reason you are designing your concept with metal?

I imagine there must be, or you wouldn't have done so.

Hopefully this inquiry will give you an opportunity to develop your idea further.

A related question ... I ** really ** don't know the answer, so please bear with me ...

While RobertDyck opened this topic with "cold plasma" you have described what I would think of as "hot" plasma....

However, I don't know enough about the subject to be able to tell what is hot and what is cold.

If you (or anyone) would be willing to spend a few moments explaining the difference, that explanation would then be available for future readers of this topic.

(th)

Calliban · 2023-12-13 19:22:13

TH, the arcjet accelerates plasma using electric fields. It is a linear electrostatic accelerator. The anode and cathode must be electrically conductive to carry the electric field. Hence the need for metal.

tahanson43206 · 2023-12-13 19:36:18

For Calliban re #15

Thanks for the reminder!

An accelerator may be designed to use magnetic fields.

Could your idea of the bursting packages of matter be accelerated by one of those?

***
Google found Linac ... apparently this is an electrostatic accelerator ...

(th)

tahanson43206 · 2023-12-13 19:50:58

Follow up ....

Per Google:

The linear accelerator uses microwave technology (similar to that used for radar) to accelerate electrons in a part of the accelerator called the "wave guide," then allows these electrons to collide with a heavy metal target to produce high-energy x-rays.
LINAC (Linear Accelerator) - Radiologyinfo.org
Radiologyinfo.org
https://www.radiologyinfo.org › info › linac
Search for: How does a linac accelerator work?
What is the basic principle of a linear accelerator?
A linear particle accelerator (often shortened to linac) is a type of particle accelerator that greatly increases the kinetic energy of charged subatomic particles or ions by subjecting the charged particles to a series of oscillating electric potentials along a linear beamline.Mar 1, 2020
Linear Accelerator - Definition, Application, Working Principle
BYJU'S
https://byjus.com › Physics › Electromagnetic Waves
Search for: What is the basic principle of a linear accelerator?

(th)

tahanson43206 · 2023-12-13 20:05:00

Further follow up .... An article I found included invention of the cyclotron after the inventor saw an article about linear accelerators.

This leads me to wonder if a cyclotron accelerator might work to accelerate ions from the exploding packet?

I assume there must be a way to guide the particles to a desired exit port.

The link below points to a paper written by an MIT student towards a bachelor's degree ... it describes a machine to accelerate protons to 2 Mev, which is (I gather) suitable for student laboratory experiments (at MIT).

http://web.mit.edu/ldewan/Public/22thes … esis10.pdf

In thinking (a bit) about the problem being solved, I get the impression that the mass of the particles to be accelerated is a critical factor in success of the venture.

In contrast, the vision of Calliban, of ionized matter resulting from the violent disturbance of a small package of matter, would require all manner of sizes of particles to be accelerated. In addition, the particles would necessarily be ionized with or without electrons, or the electrons would be dislodged and floating about freely. The electrons would go one way, and the positively charged ions would go the other, assuming the presence of an electric field.

(th)

Calliban · 2023-12-14 04:35:46

There are many different electric propulsion methods that could work. VASIMR is probably the best known and is essentially a microwave heated rocket engine, with plasma kept away from the chamber walls by a static magnetic field. That could be made to work with regolith propellant as well, as the polyethylene pellet coating can be heated to hundreds of thousands of Kelvin, effectively vaporising the pellet and converting it into a conducting plasma. Lasers are a poorly efficient method of heating propellant. But a straight forward laser ablation, with plasma contained in a static magnetic field and spraying out of the engine like a rocket, is also an option. The reason I proposed accelerating the plasma using an electric field is that electrostatic acceleration is more energy efficient than a straight forward laser ablasion rocket. Also, an electrostatic engine is a very simple and rugged device. It is something we can make replacement parts for on Mars. Come to think of it, if voltage is high enough we wouldn't need a laser. But the breakdown voltage gradient of the metal oxides in the pellet will be at least several hundred thousand V/m. A laser obviates this problem by ionising the pellet, allowing the conducting vapour to be accelerated by electric field. Yet another option is a high frequency oscilating magnetic field. If part of the pellet is conducting at room temperature, this would turn it into a hot gas that can generate thrust.

The thing that seperates this concept from other electric propulsion options is the use of regolith or really any material that we find as propellant. Fitting the large ship with an engine that can use any material as propellant, dramatically simplifies the logistics of refuelling. It means we can take the ship almost anywhere. It becomes tye proverbial mule that lives off mountain scrub. Such an engine might do well in an asteroid mining situation. The things of most value are exotic metals and volatiles like water, ammonia and organics. Silicon dioxide, iron oxide, and magnesium and aluminium silicates, are slag materials that we will have a lot of and might as well use as propellant.

A mass driver (coil gun) could accelerate these as solid lumps. We could accelerate cast slugs of material. But a mass driver is a large, massive and complex electromechanical device. Unless our ship is hundreds of metres long, it probably isn't optimal from a thrust-weight or reliability viewpoint. But Gerard O'Neill did quite a lot of work on the development of mass drivers and believed that an exhaust velocity of 10km/s would be achievable with 1980s technology. So this is an option for large ship propulsion.

Last edited by Calliban (2023-12-14 04:52:40)

tahanson43206 · 2023-12-14 07:28:42

For Calliban re 19

Thank you for enlarging the scope of the discussion, for bringing in VASIMR, and for clarifying how the system you are describing would differ from other visions.

A consideration for ** all ** these systems is the downstream consequences. There won't be any obvious consequences of generating high velocity mass streams when humans first venture into space, but as human presence grows, highly energetic mass streams are going to become part of the threat environment.

Just as thoughtless flight into space from Earth has created a cloud of debris that threatens space craft now in LEO, so will creation of energetic mass streams create dangers for humans between planets at some future time.

It's not particularly helpful to say that space is large and chances of encounter with a highly energetic mass stream are low. A vessel that encounters such a mass stream will experience erosion of it's outer surface at the least.

Space traffic control procedures will eventually require that operators reveal/report the generation of mass streams, and those mass streams will have to be tracked when they are in human occupied space.

(th)

Calliban · 2023-12-14 07:58:18

Yes, if we relied extensively on mass drivers expelling solid slugs for propulsion, we would eventually create an increased risk of collision. But as things stand, there are estimated to be 500 million near earth objects with diameters exceeding 3.5m.
https://en.m.wikipedia.org/wiki/Near-Earth_object

The number of house brick sized objects will inevitably exceed this number. So the problem will only become significant if we operate a lot of these ships for a timescale of centuries. Many of the slugs will either burn up in Earth or Mars atmosphere, or collide with Venus. So most of these things won't be hanging around for timescales of centuries.

One way of averting the problem is to use fine dust instead of solid slugs. That way, sunlight pressure and solar wind will blow the dust out of the solar system.

Last edited by Calliban (2023-12-14 08:01:21)

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Low temperature plasma

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