High Energy Weapons and EMP

[Jeff M. Hopper]

An odd thought occured to me. Wouldn't a fusion gun or a plasma gun produce EMP-like effects in thier target since they are both shooting highly charged plasma? Granted the heat and impact damage would be great, but would the plasma bolt itself cause and electromagnetic pulse in the target's electrical system (assuming it has one). If it it can do this, then could a plasma or fusion gun be "tuned down" so that an EMP effect is all that it produces in a target?

 

[far-trader]

Interesting idea, an EMP gun that is. I have seen it in some sci-fi but the whole Plasma/Fusion gun thing is buggy so tagging this onto it is suspect. But not so suspect you couldn't just wave your hands and make it so, much like the way the rest of it "works"

My question would be what protects the user and the gun from the same EMP effect? Unless you use a model where the Plasma/Fusion is contained in a small shell until it hits the target, but then you can't really tune it for EMP only either.

Also, if it is the high energy state of the Plasma/Fusion that produces the EMP how do you raise the EMP effect and reduce the Plasma/Fusion effect? The two would be tied together wouldn't they?

I'm not even sure the energy levels are high enough for a significant EMP effect on hardened mil hardware anyway, which is what it will mostly be used against. Civy stuff maybe but then it will be toasted by the Plasma/Fusion anyway. I think what you're looking for requires a simple (or hard) new weapon, an EMP Gun that is used only to fry electronics at range, probably a law enforcement tool or handy device against civilian rabble. It would be of limited use against mil or para-mil hardware since that would be built to counter such. Heck even a lot of civy high tech stuff would probably be hardened against.

 

[far-trader]

A quick refresher of EMP effects seems to suggest it requires Nuclear Bomb level energy and an atmosphere to produce an EMP, and further you need an "antenna" to pull in the EMP. Any long conductor (about 1 meter) would do but that makes protecting a device from EMP dead easy, just avoid an "antenna" in or connected electrically to the device. A simple Faraday cage is also sufficient protection so most gear within vehicles and craft are safe by virtue of the metal chassis, if properly insulated within.

So I don't think the Plasma/Fusion gun is going to produce an EMP effect and making a gun that can do it is pretty much space opera level sci-fi, cool but not likely.

 

[Anthony]

While a true EMP requires a nuclear weapon, HPM (high power microwave) weapons have similar effects, and can be produced fairly easily with conventional explosives.

Plasma/Fusion weapons will produce a microwave pulse from two effects: the magnetic field used to direct the blast will produce an immediate pulse, and if there is a current passing through the plasma (there may not be) the beam will also produce a pulse of microwaves.

Both effects are more likely to kill the electronics in the firing platform than to kill the electronics in the target.

 

[Uncle Bob]

Actually, a charged plasma moving at near-relatavistic speeds through the air is a current. Military level shielding should protect individual or vehicle electronics. Against typical civilian level protection a miss by 1-2 meters by a PGMP (2-5 for a FGMP?) should fry the radio, night vision, engine electronics, etc.

 

[Spinward Scout]

Let me ask my brother tonite. He did his Master's Electrical Engineering Thesis on EMP shielding. Now, I've read a little and there is an EMP bomb out there - or at least plans for one. There was a Popular Science article about it (Google might help). But, from what I know, I think the EMP would generate inside the gun when the little bit of hydrogen goes fusion. So, there would have to be shielding inside the gun. As far as plasma guns, I'm sure there's tons of ionization, but no EMP.

I'll check tonite with my brother,

Dameon

 

[Anthony]

Originally posted by Uncle Bob:
Actually, a charged plasma moving at near-relatavistic speeds through the air is a current.

Yes, it is, but we don't know whether the plasma is charged. It's ionized, but that isn't the same thing.

 

[Jeff M. Hopper]

Originally posted by Anthony:
</font><blockquote>quote:</font><hr />Originally posted by Uncle Bob:
Actually, a charged plasma moving at near-relatavistic speeds through the air is a current.

Yes, it is, but we don't know whether the plasma is charged. It's ionized, but that isn't the same thing. </font>[/QUOTE]This is an important consideration. For myself, I'd always assumed that the plasma was charged and kept cohesive by internally produced magnetic effects, kind of like a solar flare around a twisted magnetic field line from the sun.

 

[TheEngineer]

Hi !

Usually a plasma is neutral on a macroscopic scale, consisting of electron stripped ions and a a gas of these electrons. OTOH plasma charging can indeed oscillate on a high frequence, creating periodically charged areas on a microscopic scale, but the plasma stays neutral viewed from the outside.
Well, general neutrality would be quite important for something like a "plasma-bolt", which has to keep internal shape for travel to target, as enduring high concentrations of identically charged particles might destroy the encapsulating m-field structure.

Anyway, this kind of stable state is quite sensible to magnetodynamic influence from the outside.

So I could think, that just the approach of the bolt of the target might disturb the plasma structure, causing chaotic charge shifts and thus resulting in a pretty additional EMP effect.

 

[Uncle Bob]

Also, IIRC, partical beam weapons in atmosphere are allways charged PBW because collision with the atmosphere strips electrons from a neutral beam. I assumed the same would be true of even a neutral plasma.

 

[Anthony]

Well, plasma guns have the fundamental problem that they involve incoherent physics (a realistic version would just sort of produce a cone explosion at the muzzle). That makes it hard to isolate exactly what effects they should have.

 

[TheEngineer]

Usually plasma and particle beam research is performed in vaccuum environment.
Something like athmosphere interaction seems not to be a central topic of real life experimental physics, so its difficult to find "hard" information

Anyway mathematical approaches and MHD computer sim models show, that there are stable solutions for self stabilizing plasma structures (in vaccuum). Unfortunatelly we are not able to create the "initial" stabilty as perfect as it is needed . AFAIK thats an essential problems for fusion research, too.

Do You know this one ?:
MagBeam

 

[Ptah]

Originally posted by Anthony:
Well, plasma guns have the fundamental problem that they involve incoherent physics (a realistic version would just sort of produce a cone explosion at the muzzle). That makes it hard to isolate exactly what effects they should have.

Plasmas have a major benefit over laser (coherent light) based weapons: a plasma does not suffer from beam divergence like a laser. The impediment to development of a plasma weapon is a technical one not a fundamental one. That is, there exists a real world theory and physics that explains how a self containing plasma can exist and can be created. To quote The Engineer:

Anyway mathematical approaches and MHD computer sim models show, that there are stable solutions for self stabilizing plasma structures (in vaccuum). Unfortunatelly we are not able to create the "initial" stabilty as perfect as it is needed . AFAIK thats an essential problems for fusion research, too.

The impediment is technological implementation not implausible physics. In short, plasma weapons are not IMHO unrealistic at higher TL in the slightest. [mini-rant] In comparison, the description of lasers appears to ignore that even a very, very, very small beam divergence could easily render a laser useless as a weapon at the combat scales typical of space combat (e.g., 1000's to 10,000's kilometers). The fixes (e.g., mulitple-lenses, gravitational lenses) proposed for this problem are based on far more unrealistic physics than the physics for an effective plasma weapon. [/mini-rant]

 

[Ptah]

Originally posted by TheEngineer:
Usually plasma and particle beam research is performed in vaccuum environment.
Something like athmosphere interaction seems not to be a central topic of real life experimental physics, so its difficult to find "hard" information

Experimental phycsical chemistry and atmospheric science might have some answers.

I agree with Uncle Bob that a neutral particle beam composed of atoms (instead of neutrons) with a low enough ionization potential will ionize on traversing an atmosphere. In addition, the scattering due to collisions with the atmospheric atoms/molecules would attentuate the particle beam and leave a trail of ionized gas in its wake. Add enough ionization and such weapons might also induce lightning strikes as the ionized atmosphere seeks ground.
Probably a very pretty effect, streaks of ionized gas with lightning branching off of them.

With respect to plasma weapons in the lower atmosphere, I'd imagine that the collisions of the atmospheric atoms/molecules would weaken/destabalize the MHD field containing the plasma by collisons with the ions/electrons in the plasma which in turn would alter the electromagnetic field lines in the plasma. Initially, this might result in an expansion of the plasma "bolt" as the field weakens and/or the field may collapse and the plasma "bolt" explode. This interaction would also leave a trail of ionized atmospheric atoms/molecules in its wake and create the potential for lightning strikes.

With respect to plasma weapons from orbit, a major question would be whether the planet has an ionosphere and magnetosphere. These could induce destabaliztation of the field containing a plasma "bolt" by ions and the planets magnetic field interacting directly with the MHD field, a potetially stronger destabalization than collsions with neutrals in the lower atmosphere.

 

[mike wightman]

Originally posted by TheEngineer:
Do You know this one ?:
MagBeam

That sort of reminds me of the system rapid transit network in the computer game Freelancer - trade lanes they were called.

 

[Anthony]

Originally posted by Ptah:
Plasmas have a major benefit over laser (coherent light) based weapons: a plasma does not suffer from beam divergence like a laser.

No, but they do suffer from thermal scatter, which is vastly worse than laser beam diffraction.

 

[Spinward Scout]

Ok, talked to my brother. That didn't help much. Found a few web pages for you, tho!

Link

Link

Link

Later,

Dameon

 

[Anthony]

The first link describes the basics of a High Power Microwave weapon. Here's a better link: http://www.globalsecurity.org/military/systems/munitions/hpm.htm

The other two links are about fusion, and are largely irrelevant to the problem of plasma beam cohesion in the open -- as long as you have an external magnetic field, plasma beams can stay intact, otherwise they're prone to acting like any other hot gas and expanding rapidly. While I don't know that it's impossible to generate a magnetic field within a plasma that would hold a plasma blob stable, I also don't know that it's possible, and usually internal magnetic fields result in repulsion (blowing the cloud apart) not attraction.

 

[TheEngineer]

Hi !

In real life plasma "blob" stability is observable in fairly large astronomical scales.
E.g. suns prominences (hope its the correct word) create plasma regions with a stable, "frozen" magnetic field. Same effect seems to be related to AGN jet streams.
The mag field and plasma geometry freezing effect is also visible at smaller scales, but dont last long enough here.
As I said, self-containing plasmas in vaccuum are still a topic of theoretical MHD calculations assuming perfect fields and perfect plasma composition right now.
Somehow related to this topic is the existence (or non-existence) of ball lightnings, which are sometimes described as self stabilizing plasma effects.
IMHO the MagBeam project gives some interesting hints on plasma physics future.
The rest is just science fiction, but thats what we're playing with

Another way to keep plasma bolts in shape (and even "reduces" effects of stripping) really would be to let them travel at relativistic speeds. Time delation would keep plasma geometry intact in the observers frame.
But if we would use such velocities and the involved pure kinetic energies, where is the sense to mess around with something in a complicate plasma state anyway ? You might use any dirt here and would call it a PAW.
To me relativistic plasma beams make less sense, so I just assume the ability to create "low" velocity self containing plasma blobs (LVSCPB) at TL 10+ in my game. With all the discussed side effects it also appears to be quite cinematic. (Well, I still have not found a really convincing pseudo explanation, why the blob is not torn apart from simple scattering - beside the electron stripping - with the athmosphere molecules...especially at long ranges like "planetary". Umm, perhaps the encapsulating mag field serves as a shield against paramagnetic oxygen or so...).

Regarding general particle beam scattering in the athmosphere I found a very pretty document "Reconstruction and selection of extensive air showers at the KASCADE-Grande-experiment". Well, its in german but contains some nice figures even for the english speaking folks.
Here's the link for those interested:
CASCADE experiment docu

Referring to this document, the shower cone created by a orbital PAW using high energy particles (protons) of say 1 GeV (particles of such energy levels are hardly deflected by earths mag field) on the planetary surface might be pretty narrow (<100m) with a noteable density maximum in the center, even if no primary particle reaching the ground.
What really strikes me, when calculating around with PAWs is that when using those 1GeV particles, the mass of one "round" deploying 1000 MJ is just 1E-8 kg, so really just a piece of dust !!.

 

[Ptah]

Originally posted by Anthony:
</font><blockquote>quote:</font><hr />Originally posted by Ptah:
Plasmas have a major benefit over laser (coherent light) based weapons: a plasma does not suffer from beam divergence like a laser.

No, but they do suffer from thermal scatter, which is vastly worse than laser beam diffraction. </font>[/QUOTE]I believe MHD theory supports the possibility of a plasma generating its own self-containing field (you just may need to “spin it up” right in your gun first and make it a very hot one to keep it's lifetime up since it's small).

I'm not a high-temperature plasma physicist though, my knowledge is limited to working through Jackson's Electrodynamics and research for the AFOSR on weakly-magnetized plasmas and plasma sheath formation on space-craft in low earth orbit, so my understanding of the plasma physics in this regime may be off. I can usually follow the MHD equations to a point, and from what I've been able to infer from MHD theory is that self-contained plasmas are not impossible, but our analytical theory in this field is still incomplete. From what I've been able to infer, the shape of the plasma "bolt" is more likely to be some sort of toroidal shape.

While I don't know that it's impossible to generate a magnetic field within a plasma that would hold a plasma blob stable, I also don't know that it's possible,

My understanding is it's not impossible. But I'm willing to err a bit on the side of possibility when predicting technology at TL10+. (I always try to remember that if I used the physics of the 19th century (~TL 6)I wouldn't have been able to predict the lasers of today, or the biochemistry of 30 years ago (~TL7)to predict RNA as an enzyme ) Accordingly, I'm also willing to accept that some means has been found to travel FTL, artificial gravity, and laser weapons that can be effectively focused over 1000s of kilometers at higher tech-levels, so I'm pretty easy on the sci side of things.