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So, since practically every science fiction writer under the sun has imagined some manner of handheld laser beam, I have been exploring alternatives for energy/particle weapons, one of which is an electron beam. These are appealing since they would presumably not require some kind of externally-sourced ammo like a proton or neutron beam, (though they would presumably require charging) and because a gun that fires a perfectly straight bolt of lightning is bound to look pretty cool.

However, not wanting to get ahead of myself, I would like to know some of the technical requirements. Apart from some form of magnetic accelerator tube to direct the electron beam, what are the most important parts a weapon like this would need?

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    $\begingroup$ Do you mean is space or in an atmosphere? $\endgroup$ Commented Jan 23, 2023 at 11:38
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    $\begingroup$ What is special about an electron beam that "they would presumably not require some kind of externally-sourced ammo like a proton or neutron beam"? $\endgroup$
    – Daron
    Commented Jan 23, 2023 at 12:59
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    $\begingroup$ @Gillgamesh: It also needs to generate a vacuum like inside the cathode ray display tube... $\endgroup$
    – AlexP
    Commented Jan 23, 2023 at 13:20
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    $\begingroup$ ... and have an anode collector to return the electrons. Also, lightning is electrons traveling along a gas-plasma. Going to take quite a bit of energy to create and directionality needs to be achieved. Getting it to hit the target as opposed to the nearby ground would seem to need a method of generating a plasma stream to the target even before discharge occurs. See: Lightning Rifle. $\endgroup$ Commented Jan 23, 2023 at 14:36
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    $\begingroup$ @AngryMuppet RE Lightening Rifle. There's a good example of how SE's rules have changed! Look at all those questions! Long before SE implemented "Needs More Focus." $\endgroup$
    – JBH
    Commented Jan 24, 2023 at 0:44

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For most purposes, electron beams make very poor weapons.

First there is the old "this hurts me more than it hurts you." Electron beams are notoriously low efficiency. If you can only get a few percent of the energy you use into the beam, then you have to dissipate a lot of waste heat.

An electron flying through air will have a relatively short range. If you managed to get the electrons up to a few million volts, they might travel a few meters through air. Electrons being charged, and being relatively low mass, they tend to scatter off air quite readily. Each scattering causes the beam to diverge quite rapidly, and the electrons to lose energy.

Even in vacuum it's not all that useful. An electron at 10 MeV is going to be stopped quite effectively by a few millimeters of even quite ordinary material. Even if you managed to get enough energy into the beam to be useful, a very thin ablative layer dissipates the heat quite efficiently. And then the layer of gas from the ablative layer acts as an efficient shield until it disperse.

Then there's the very easy dodge of having some magnets on your hull. The electrons get deflected rather effectively. With a little bit of jim-jam with such magnets, you might even manage a mirror effect. That would be alarming, to fire your super weapon and have it bounce back at you.

There are some non-beam weapons that might get you some application. If you are shooting in atmosphere, for example, you want to effectively create a lightning stroke. You ionize a path of air to the target, say by a laser tuned to heat air. Then the ionized air can act as a conductor for a high voltage surge, with the return being the ground. In principle this could be useful to do things like touch off their ammo, fry their electronics, etc. This works because it is conducting rather than a beam. The electrons are moving much more slowly than in a beam. Such an ionized path can be quite low resistance.

Bullets with capacitors in them might be useful in limited circumstances. The capacitor gets charged up with a few million Joules of energy. When it hits the target this energy is released somehow. Say by a short circuit or a closed circuit through a small coil. Again it is useful for touching off their ammo or frying their electronics.

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  • $\begingroup$ The laser heating idea will work even more reliably if you shoot two beams, one with the return path. The thing being, your electrogun is insulated against that high voltages and currents but the opponent's target point is not (frying antennae is big fun I guess). $\endgroup$
    – toolforger
    Commented Jan 24, 2023 at 12:18
  • $\begingroup$ Your answer should mention that a laser-guided electroweapon wants a medium, i.e. air or (maybe?) water. It won't work in vacuum.) $\endgroup$
    – toolforger
    Commented Jan 24, 2023 at 12:18
  • $\begingroup$ @toolforger Maybe I should continue to mention "shooting in atmosphere." $\endgroup$
    – Boba Fit
    Commented Jan 24, 2023 at 13:55
  • $\begingroup$ "The electrons are moving much more slowly than in a beam." <- While technically true, they will still be moving at relativistic speeds which is effectively instant when talking about hand-held weapon engagement ranges. With both options able to cover the distance to target in close to a microsecond, the real question is about how much time it takes to discharge a fatal amount of energy, not how fast the energy gets there. $\endgroup$
    – Nosajimiki
    Commented Jan 24, 2023 at 15:24
  • $\begingroup$ @Nosajimiki No. Electrons in lightning are moving about 60 miles per second. Light moves 186,000 mps. The reason moving more slowly is important is as stated, they don't lose so much energy from scattering. $\endgroup$
    – Boba Fit
    Commented Jan 24, 2023 at 15:30
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Apologies in advance for the long post. This was just too fun.

Short answer: Nope.

Read below for the ridiculously long answer.

(All images sourced through Google Images, reverse search if you want the actual sources.)


Throwing electrons around is hugely problematic, and it gets worse when you're trying to pump enough electrons into a target to get them to stop trying to steal your dog or something.

There are two basic ways to get electrons from A to B: conduction and radiation. Both of them require specific conditions (like something to be conducted through for a start) and are notoriously hard to control. Turns out electrons are pretty damn chaotic.

Since it's in the title, let's start with the "electron beam" (radiation) idea, and see if we can figure out why we don't do this.

Here's a real-life electron beam gun:

Bamboozled again, is actually television

Looks like a 1950's SciFi gadget, but this is a real thing you can pick up right now for a couple hundred dollars brand new. All those fiddly little bits inside the glass are an electron ray gun. Push the right amount of power at the correct frequency and voltage into the right pins and it generates a durable electron beam down the tube... where it splashes against a metalic grid and returns as electron pressure to complete the circuit.

Those of you my age (I pity you) or interested in retro tech will recognize this as a Cathode Ray Tube. Specifically a 11LO3V CRT tube for an oscilliscope.

Three problems for your use case:

  1. There has to be a return path.
  2. The beam has to be focused by an external electromagnet ring.
  3. The beam can only form in the partial vaccuum of the tube and cannot travel outside the tube.

Or perhaps you recognize this:

I wouldn't stand there

Perhaps not. That's a shot of a machine at CERN that, apparenty, is being setup to accelerate electrons and smash them together hard enough to - hopefully - blow them to tiny bits. (Presumably in God's mercy.)

OK, that's probably an extreme example. I'm sure we could get it down to a manageable size. Put it on a diet, get it to the gym, maybe shave a few thousand tons. Maybe something like this:

That's better, we can carry that

What do you mean that's only one component? Come on man, I'm trying here!

Anyway, nope, not going to happen. Read the other answers for why not, those guys are smart.

So what about conduction then? We see a lot of that, both in nature and in our technology. Well, we mostly only see it when our technology fails. In nature though we see it a lot like this:

Pretty!

The interesting thing here is how hard it is to control. A lightning strike starts with a ground charge ionizing a path through the air until it forms a circuit to the charged cloud mass, which then discharges enthusiastically along that conductive path. Sometimes that path is strong and straight enought to result in a relatively clean strike, but very often it looks like the picture above where the electrons in the strike branch out and excite molecules in the air to form plasma. Very hot, very high energy, mostly deadly.

But if we raise the voltage high enough we can in fact get electric arcs even without the ionized path. The arc will form it's own ion trail from the plasma it generates while establishing itself. In fact we've already created guns from this effect:

Ooh, toys!

Not sure when "shooting people with electron beam plasma" became a hobby, but I guess people do stranger things for fun.

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All this is off the top of my head, but the difficulties of an electron beam, or any charged particle beam is directing it toward a target with any kind of accuracy. The holy grail of particle beams is a neutrally charged one that can be fired an will not be susceptible to magnetic or charged fields. This limitation includes the ion been itself. As the beam is charged nd same charges repel. The beam will diffuse over a distance. becoming wider and wider as it travels and the individual particles are repelled away from one another.

Other than a neutral charge, I've heard few workarounds to the limitation of working within a magnetic field. This only affects beams within a planetary magnetic field. solar fields over a larger scale, and where one would produce a defencive field as a countermeasure against such weapons. In space generally they make perfectly serviceable short to medium ranged weapons. though easily countered.

As far as a handheld device. A plausible work around was proposed. Using a "lower powered" laser to precede the ion beam and strip the electrons away from atoms, negatively ionizing the air between the positive ion beam emitter and the target, a fraction of a second before the ion beam fires. Thus producing a tunnel or conduit for the beam to travel through. This would look like a flash of light and a quick sharp crack!-CRACK! sound as the weapon fires.

Sorry for lack of sources/formatting but I'm on my cell phone in a waiting room :)

Edit: Still in line, so I thought I would add: Particle beam < Laser.

A laser must rest on a target for a time, to transfer heat to do damage to the target using photons.

A particle beam (ion being a type) is essentially a kinetic weapon, on a subatomic scale its a sand blaster. It does not need to rest on the target to cause damage. Indeed in addition to this at high energy a particle beam will produce secondary radiation like x-rays or other ionizing radiation.

This list can go back and forth but these are the affects they manifest.

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    $\begingroup$ Recently there's sciencealert.com/… -- use lasers to build an air waveguide and then use that channel to be a 45m long laser. $\endgroup$
    – Dave X
    Commented Jan 24, 2023 at 1:18
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This is a Frame Challenge

Most SciFi writers stopped referring to the deadly light show as "lasers" a long time ago — for some very good reasons

And most of them boil down to economics.1

Any energy weapon fired inside an atmosphere loses energy to the atmosphere. Any energy weapon with enough strength to bring down, say, an Elk would loose a lot of energy to the atmosphere. Worst of all, everything affects the efficiency of the energy beam (humidity and precipitation, temperature, pressure, etc.) just costs more energy. That battery is getting big!

Add to this that all energy weapons require focus. There's no such thing as a columnar beam of energy that won't disperse over distance. Worse, if you don't focus, energy is lost due to the poor focus (there's that battery again). The ability to focus the weapon on your target is no small thing. Not impossible, but a big deal. With enough Clarkean Magic you can claim that the focus is, perhaps, magnetically achieved. But insofar as we understand energy today, your only option is to vary the distance between two lenses — a mechanical action that's more prone to dirt than the action on a projectile weapon.

And when it comes to electricity-based energy weapons, most people forget that electricity travels along the most conductive path to ground. That will almost never be your target (unless they happen to be standing in front of a copper rod pounded a couple of meters into the ground... and even then, hopefully you're not shooting over a ditch full of water or the humidity's high enough to make the path around the body more conductive than the path through the body).

How do you overcome all this? Better optics! Bigger power packs! money, money, money, money, money....

Bullets are cheap

To make a point, the only reason to use an RPG is because the object you're shooting at can't be brought down with a deer rifle. The only reason you use a howitzer is because the item you're shooting at can't be brought down by an RPG or a deer rifle. The only reason to use an ICBM....

You get my point.

If you're trying to be realistic (and judging from your desire for specifics about electron beams, you're trying to be realistic), then no energy weapon is practical. The cost of the high-density power pack, self-cleaning unbreakable optics, dynamic focusing... money, money, money, money, money....

And on top of that, guess what happens when some lucky bullet happens to strike the power pack for your pistol? Yeah. No more leg. Dirty optics? Useless weapon. And the ionization trail an energy bolt would leave behind might as well be an arrow pointing at you with a big sign that reads "this guy did it!"

Star Wars (1977) really popularized the idea of a "blaster"

...and nobody (until much later) had any idea how it worked. It did things no energy weapon should be able to do (like create a bolt that could be seen independent of the target and the gun for a period of time...). It was really bright and amazingly flashy and the idea was preposterously fun! Until later when people who had too much time on their hands who just couldn't leave good imagination alone had to try to explain the weapon as firing a plasma bolt.

But Lucas was a genius. He knew perfectly well that trying to explain the details of technology ruined a good story. And along with many other things, Lucas was in it for the money....

Conclusion

Economics, my friend, is why energy weapons won't be used anytime soon. They cost too much. And even if you overcome that, there's all the other problems.

You don't need to explain your energy weapon. It's not worth explaining it, because once you explain it, there are whole classrooms full of people who can and will explain to you why you can't use it. As I said, no energy weapon is practical.

But that doesn't mean they're not cool.

Go ahead and use an electron-beam pistol! But don't waste your time worrying about how they work or why they won't... because if you dive down that rabbit hole, you'll discover the ugly truth.


1 I'm a huge fan of pointing out how most worldbuilders and story tellers ignore economics. What's the biggest reason why something might not be done? It's too expensive. That's true in real life, too.

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  • $\begingroup$ I mostly agree, but there are a few real-world applications where directed energy weapons are beginning to outperform ballistic weapons. Nearly every 6th generation fighter currently under development plans to phase out air-to-air missiles in favor of high energy lasers because lasers can take down hypersonic targets and satellites much more easily than a missile can. You can't really dodge or outrun one; so, thier damage to weight inefficiency is well worth their practical advantages. Anti-ballistic lasers are growing in popularity for the same reasons. $\endgroup$
    – Nosajimiki
    Commented Jan 24, 2023 at 16:52
  • $\begingroup$ I don't really see lasers ever replacing riffles, but electro lasers at least can be used for things that bullets are really bad at like IED sweeping and non-lethal, instant incapacitation at much longer ranges and accuracies than wire-tasers. While economics are a real limiting factor, we know that the US happily pays 1000 times as much for a smart artillery shell because it just works better, likewise, in cases where a laser works better, the extra cost is often worth it. $\endgroup$
    – Nosajimiki
    Commented Jan 24, 2023 at 16:52
  • $\begingroup$ @Nosajimiki You mostly agree about what? The OP is asking in the context of a handheld weapon that I assume is replacing a rifle in combat. That makes your comments about anti-ballistic and minesweeping technologies, interesting as they are, irrelevant to the question and my answer. Considering only the context of the OP's question (which is all my answer applies to), in what way to you disagree with my answer? (I believe disagreeing with any answer due to issues outside the context of the question to be very much bad grace.) $\endgroup$
    – JBH
    Commented Jan 24, 2023 at 19:49
  • $\begingroup$ I agree that cost and efficiency of ballistic weapons will usually make them the weapon of choice... but only usually. And yes, it is true a hand-held energy weapon is not shooting down fighter jets any time in the near future, but my point was not so much to highlight specific applications as to point out that sometimes the more expensive, less efficient option is worth it if it helps you fill needs that conventional weapons struggle with. $\endgroup$
    – Nosajimiki
    Commented Jan 24, 2023 at 20:37
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Inside the gun you have

  1. Electron maker/capturer

  2. Supply of power/electrons

  3. Way to safely vent excess positive charge

  4. Electron Accelerator

  5. Power source for the accelerator

  6. Electron Focuser tube

Outside you have

  1. Gun Handle
  2. Insulation body to stop holder being zapped
  3. Trigger
  4. Place to attach and detach spent electron makers and power sources.
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    $\begingroup$ You forgot the vacuum generator. An electron beam won't travel far in air, at least not in any kind of predictable direction. $\endgroup$
    – AlexP
    Commented Jan 23, 2023 at 13:19
  • $\begingroup$ it wont go predictably far in in the presence of any magnetic field either. $\endgroup$
    – Gillgamesh
    Commented Jan 23, 2023 at 13:41
  • $\begingroup$ +1 for basically all he would need for a diagram of "super neato space police electron gun mk.2000" that at least has the right parts labeled. The fact that it wouldn't work flies in the face of everything sci-fi books have ever taught me and can therefore be ignored. $\endgroup$
    – JamieB
    Commented Jan 23, 2023 at 18:59
  • $\begingroup$ @AlexP The vacuum generator is long. It extends from the gun all the way to the thing we want to shoot. $\endgroup$
    – Daron
    Commented Jan 23, 2023 at 23:51
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What you want is an electro-laser (AKA: laser guided energy weapon)

This is a real class of weapon system that allows one to conduct an electrical charge in a straight line over a long distance by using a brief but powerful laser pulse to ionize a channel through the air. The ionized air becomes conductive; so, it's in principle the same idea as running a wire between a taser and the target.

There is not a whole lot of published technical documentation available for how these work since most of them are part of active military RnD projects, but based on thier description, you can pretty much extrapolate that the necessities are a powerful laser, some kind of electrical arc generator to supply the current to the laser, a few heavy duty capacitors, a power source like a battery or some future tech equivalent there of, and some electronic control systems to regulate all the parts activating together. A hand portable electro-laser would probably end up looking something like this:

enter image description here

Vehicle mounted versions of these weapons have been around for a while now, but Applied Energetics, the world leader in laser guided energy weapons, claims that making such a weapon both hand-held and lethal is doable... and given the pattern of funding and number of Government Sensitive Patents held by AE, its reasonable to assume they've either already done it, or they are very close.

The best thing about electro-lasers is that they are not just directed energy weapons, but they electrocute the target meaning that they can have both stun and kill features similar to a star trek phaser. It can also completely and instantly incapacitate an opponent no matter where you shoot them; so, while getting shot in the arm with a gun may remove a combatant from the fight in the long term, it still gives them the opportunity to keep shooting back for a while, but with an electro-laser, even hitting non-critical parts of the body will drop a person instantly so they can't return fire. These unique qualities of electro-lasers really sets directed energy weapons apart from ballistic weapons in a way that other directed energy weapons like Lasers and Plasma weapons don't. This makes it actually make since for a society to phase out guns for more expensive, less efficient "electron" energy weapons, at least in certain contexts.

https://en.wikipedia.org/wiki/Electrolaser

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You would probably need both a battery and a capacitor. The battery hold large amounts of charge long-term. The a capacitor draws just one shot's worth of charge from the battery at a time, and can throw it into action in milliseconds. The battery is at the back of the gun, the capacitor in front of it.

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I like Boba Fit's answer but wanted to add to it. If you're asking about building a realistic version of this you'd need an enormous amount of power to get any type of "beam".

The target would have to be closer to the beam than any conductive elements.

Let's say you have that power source from miniature fusion or something. The beam would likely need some form of targeting to inform the user of range and potential wonkyness from nearby conductive items. Like a steal beam would pull the beam to it and ruin your straight beam, you'd have to choose a target 5-10 feet away from it, otherwise the beam would veer off target on its own.

The other thing I'd expect is arcing. The further away the target the less power at the tip of the beam of course. But a target in the open without anything attracting the beam would likely be an easy shot.

Another thing to consider that I have no knowledge about is multiples of energy. I wonder what would happen if you had an insane amount of power. Perhaps that could help straighten its shots.

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Others have pointed out why electron beam is not so great.

So here's an alternative: electron-positron beam

That is, the beam composition is 50% negatively charges electrons and 50% positively charged positrons. When they recombine (annihilate), the result are gamma rays that, while can be stopped, require lots of shielding.

The average charge of the beam is neutral, meaning the beam could be sent very far (through vacuum, not air), the trick is to keep the annihilation in check -- the negative and positive parts of the beam are attracted to each other and since the mass is small (unless at relativistic speeds), the beam is likely to collapse kinda fast.

This requires clever engineering (scifi technobabble) to ensure that annihilation takes place at the correct distance. Thus, setting the range of the weapon is very important (more ai technobabble).

P.S. electron-positron beams can be made with lasers, woo-hoo!

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The biggest necessities for a useful, hand-held electron beam weapon would be power, a small wakefield accelerator, a small and very powerful, clean laser - and radiation shielding for the wielder.

Wakefield accelerators are already small enough to be held in the hand here and now, though the laser or particle beam that is used to drive them is far larger. Wakefield accelerators let you get electron beams that benefit from relativistic effects without needing an accelerator the size of a building, or perhaps a battleship's gun turret with some optimistic assumptions.

Electrons that are in the GeV or TeV range, or otherwise ultrarelativistic, have relativistic gammas so high that magnets won't deflect them without creating bremsstrahlung xrays, and rather collimated ones at that. Not only that, but you'd need magnets powerful enough for magnetic confinement fusion or a particle accelerator to have any significant deflection in the first place.

Furthermore, due to relativistic effects, they do not bloom over nearly incredible distances. Electron beams with sufficiently high gammas would be limited by the jitter of your sensors and whatever aimed the device, not bloom.

One thing to think about is with such a device the radiation it would be throwing in all directions would be either very unsafe, require very heavy shielding around it, handwavium or unobtanium, or mounting it on a robot or vehicle instead of holding it in the hand. Even if the device was somehow extremely clean except where you pointed it, the electromagnetic shower from the target as much as the air could cause collateral irradiation and some would bounce back to you.

Assuming you end up going with ultrarelativistic electron beams, the damage profile would go between heating a needle-to-pencil sized cross section, to threading detcord through the target in needle to pencil sized detcords. Even in the case where the beam current was low (heating more than exploding), the electromagnetic shower would 'microwave' the inside of it with radiation. Also, at least along a conical path starting from where it first hit something, it would likely activate the usual atomic suspects. I tried to find a list of those elements and what they would be activated or promptly decay into but my google fu is failing me here.

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