How would a 21st-century war play out if every country had these alien directed-energy weapons?

Question

Before we get into the gigantic wall of text, here's the question: what applications would the following device have in a 21st-century war - asymmetric, conventional, nuclear, etc. - if every country had one of them per every ten thousand occupants?

Some of the alien artifacts in the perpetual hurricane covering a notable portion of Africa have been put to use. Four of them appear to be automated factories the size of a semi truck, which were subsequently subject to intensive testing by the International Perpetual Hurricane Exploration Organization.

The problem is, these factories only produce a two things: a small pile of various materials, presumably unused, and an energy emitter device; oddly enough, they do not produce waste heat.

This energy emitter device is a 150-gram, two-foot long, foot-wide cylinder with only two external features: a pair of millimeter-wide, opaque-to-all-wavelengths apertures, one on each face. Its internal workings cannot be discerned; whenever the seemingly normal steel casing is cut open, heated over 146 degrees Celsius, cooled below -38 degrees Celsius, or dented in any way, the internal contents of the device appear to vanish. No form of modern scanning technology can view inside it without breaching the casing. Spectroscopic analysis of the casing is consistent with the steel, and spectroscopic analysis of the apertures is consistent with zinc selenide.

For plot purposes, it's a black box. Nobody knows what's inside it, how it works, or what it's made of. If you can think of a way of getting it open while preserving its contents, that way doesn't work.

This device accepts two types of input:

• charge

• range data

The device presumably receives charge via magnetodynamic coupling. Factory-fresh devices are incapable of emitting any quantity of energy; however, when in extremely close proximity to a rotating armature, the system that armature is connected to loses energy in a way that is not replicated when the armature is not in proximity to the device. This suggests that the device absorbs power in this fashion, as does the fact that the device will not fire if it has never been subject to charging. The device will store no more than ~6.1 megajoules of energy; attempts at continuing to charge it past this point result in the charging system no longer loosing energy, suggesting that the device is no longer absorbing it.

The device receives range information in terms of distance from its center when a 5-milliwatt laser is pulsed into one of the two apertures in binary, and fires when the same aperture is hit with a 10-milliwatt one.

When given a firing command and range via this method, such a device will attempt to hit whatever is at that distance with a 6.1-megajoule, millimeter-wide, millisecond-long (6.1 gigawatt), 1-picometer wavelength, 300-exahertz laser pulse fired from the aperture opposite to the one that the range and firing signal was fed into. If the range is large than the radius of the astronomical body the emitter is placed on, it will not fire.

The emitter will adjust its power input in order to compensate for any atmospheric interference, so as to ensure that the beam arrives on-target with an energy of 6.1 megajoules. It does not compensate for any obstacles that may be in its way, such as people, trees, tanks, mountains, buildings, or other such things. It performs this adjustment based on the composition of the atmosphere it is in when given the command to fire.

The emitter will not fire unless it is completely charged - i.e. has absorbed 6.1 megajoules of energy. Somehow, it is 100% energy-efficient, although the human-made magnets that are the only method of charging it are not, resulting in significant quantities of waste heat being generated (6.1 megajoules is a lot, you know).

The emitter never wears out nor (noticeably) breaks down, adding to its mystique.

It can fire as fast as it can charge, and it can charge as fast as a magnetic field can be produced around it. I have no idea how fast that is.

Let's say that, since the charging equipment is human-made, it has an efficiency of ~90%, meaning that for every ~6.778 gigawatts put into the armature/spinny-magnet, approximately 677.778 megawatts are released as heat. Cooling these things is a serious issue.

Beam divergence is not a serious issue; at the maximum range the devices are willing to fire at (6,371 kilometers), the beam was 5 millimeters wide.

Nobody knows what these devices are made of. The factories' material and energy input requests are the same each time, but use up significantly more matter by weight than the 150 grams the devices they produce weigh, which doesn't exactly help determine what said products are made of.

Attempting to reverse-engineer one of the automated factories resulted in it destroying itself in a 20-kiloton explosion that destroyed one of the very expensive research facilities assigned to the project. The IPHEO stopped trying to reverse-engineer them after that.

Yes, I am aware of how much 6.1 megajoules is. That's roughly comparable to a shell from a tank's main weapon.

Yes, I am also aware that this thing is a cylinder the size of an office trash can, and yet weighs only 150 grams. It's alien tech. Ssssh.

Just to repeat the question: what applications would the above device have in a 21st-century war - asymmetric, conventional, nuclear, etc. - if every country had one of them per every ten thousand occupants??

Answer 1

6.1-megajoule, millimeter-wide, millisecond-long (6.1 gigawatt), 1-picometer wavelength, 300-exahertz laser pulse

1 picometer wavelength gives a photon energy of ~1.24MeV. That's comfortably into the hard x-ray, gamma ray regime. From the relevant NIST tables, you can see that this gets a mass attenuation coefficient of somewhere between 1.8 and 2cm²/g. Throwing that into the Beer-Lambert equation (supplied in that last link) shows that you've got a maximum energy loss of ~14% per metre that the beam traverses. Given the beam power though, actual losses per metre will likely be lower.

A millimetre diameter cylinder that's a metre long has a volume of ~7.5x10^-7m³, and filled with nitrogen at STP that'll have ~3.5x10^-5 moles of the gas.

To fully ionise nitrogen you need about 600MJ/mol. Assuming zero beam divergence and a pure nitrogen atmosphere, your beam will therefore lose ~21KJ/m. This gives you a maximum range of 290m in air.

Additional pulses that are delivered before that cylinder of air gathers its electrons back together will of course travel slightly further, as it will more or less shoot straight through plasma without being significantly attenuated.

It bears remembering that the energy released in this way is equivalent to a hand-grenade per 10m of air traversed by the beam... that's something of a bang, though there won't be any associated shrapnel. What there will be is a blindingly bright flash of light, a very loud bang, and an awful lot of scattered hard radiation and maybe a bit of secondary radiation too.

The emitter will adjust its power input in order to compensate for any atmospheric interference, so as to ensure that the beam arrives on-target with an energy of 6.1 megajoules.

Not without potentially releasing more energy than it was charged up with. Is that really what you want? Given a long enough line of sight, it could require orders of magnitude more energy released from the device in order to deliver the desired amount on target.

what applications would the above device have in a 21st-century war - asymmetric, conventional, nuclear, etc. - if every country had one of them per every ten thousand occupants??

Trying to use it as a weapon on Earth will be largely futile, and probably astonishingly hazardous for the shooter and anyone around them. Lots of radiation poisoning, probably quite a lot of it fatal. It will be much more effective as a weapon in space.

I'm sure it will have all sorts of non-weapon-related industrial, scientific or even medical uses on Earth. But only an idiot would try to shoot someone with it, and they might not be able to do it more than once.

Take home message?

X-ray lasers are for space warfare only.

Tone it down a bit, if you wanted something that's more dangerous to opponents than operators.