Watch the U.S. Navy's new laser weapon take out two ships in the Persian Gulf

boing
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The nose cones of self-guided missiles are usually made from transparent ceramics. Often from corundum, the one that took down that U2 plane reportedly had a corundum tip. Took Russians a while to realize they need more pure Al2O3 precursor…

But you can wreak quite some havoc with the stuff underneath. The infrared sensors especially will be fairly sensitive to damage.

I am not 100% certain what materials are GPS- or gyro-guided missile nose cones from. Will probably depend a lot on their speed and the aerodynamical heating they have to cope with.

Or, more likely, a poor hand grenade and a rude surprise. Unopened cans tend to explode when steam forms inside with sufficient pressure.

True; remember the Death Squads in Latin America. But the same relatively low-cost high-impact option is available to both sides, unlike the high-end high-tech high-cost military toys that aren’t so “democratic” in accessibility. So while optional for the strong, it is almost mandatory for the weak.

Easy solution. Make a law that every boat has to have a suitably placed explosive charge, laser-accessible from outside.

Pulsed laser can make a shock wave in the material on impact. But then we have the additional problems with air ionization at too high power densities and other pesky laser-gas interactions, so a continual beam may be a better choice if we aren’t in the optics-friendly vacuum of space.

Then it’s cyberwar for you. Better channel some of the sweet defense $billions to securing SCADA.

The average human head is 6-7 inches wide and 8-9 inches long. That corresponds to range of resonances for frequencies between 1.3 and 2 GHz (without correction to signal slow-down in non-vacuum environment which the head is, with exception of certain people). (And their harmonics, but they have much lower penetration depth in tissue the higher the frequency is.) So such cap will make you safer against thermal effects of a laser (add a spacer, though, the metal may get hot) but, paradoxically, more vulnerable against frequency-swept microwave weapons. An insert of microwave absorbing material, e.g. carbon-loaded rubber (like used as the early radar absorbent material on German submarine snorkels), or a suitable ferrite, will help to suppress this effect.

It’s definitely pretty. But also looks like easy enough to DIY.

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My guess is that they use a flat slab of neodymium-doped host crystal. It has to be a crystalline material as amorphous ones have too poor heat conductivity, flat in order to facilitate heat removal, and multifaceted to provide long enough path through the gain medium. I think I saw pictures somewhere online.

Fiber one would be a nice variant.

FEL would be definitely the sweetest.

Yessss!

I was looking at the designs a few years ago when thinking about a DIY variant. Which, while complex, shouldn’t be that much impossible.

Vacuum tech is GROSSLY underrepresented in the DIY/garagelab/hackerspace sector, compared with its usefulness. There are amazing things that can be done merely with a mechanical workshop, glassworking tools, and a pump. Look at all the tech that was there before the Age of Solid State; and even these days some of the high-power things (sprytrons and traveling wave tubes, I am looking at YOU) are still vacuum based. Take that tech, add 3d printing from sintered ceramics and metal, and the world of pulsed-power possibilities is opening wide.

…we need cheap opensource-designed turbopumps…

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I didn’t know they made a non-lethal model of the M61 Vulcan

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If you do this to a fuel tank, you start a fire.

If you do it to a human, they will jump overboard or divert their course.

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Blindly! Perhaps permanently? “He’ll live.”

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Oh jeez, don’t give them ideas. First the NSA, now the Navy, next, the Police will demand we all start wearing heart plugs ala Lynch’s Dune.

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Thank you for prompting me to learn more. What I had meant (using poor terminology) was that if exploiting the weakness of the other was the only effective thing to do, that thing sounds like a good… action. I see how the terms you reference were jumbled together almost interchangeably in the posts.

From wikipedia: Asymmetric warfare can describe a conflict in which the resources of two belligerents differ in essence and in the struggle, interact and attempt to exploit each other’s characteristic weaknesses. Such struggles often involve strategies and tactics of unconventional warfare, the weaker combatants attempting to use strategy to offset deficiencies in quantity or quality.[1] Such strategies may not necessarily be militarized.[2] This is in contrast to symmetric warfare, where two powers have similar military power and resources and rely on tactics that are similar overall, differing only in details and execution.

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High vac is not cheap enough for a DIY presence, and is not likely to be anytime soon. Turbopumps aren’t easy to manufacture, they require a roughing pump to get down to where you can start the turbopump, and thus require nice, well machined valves, and the cheapest thing that will function as a pressure vessel is thousands of dollars.

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That’s one of the problems that needs to be addressed.

The rotors need annoying precision and the bearings are rather high-end. I wonder if magnetic-levitation bearings could be used. Possibly yes. I also wonder how high precision is needed for the rotor blades, beyond sufficiently perfect balancing and tensile strength to avoid centrifugal force fragmentation. If laser sintering would be enough and where are the catches.

The roughing pump is a bog-standard piece of equipment.

You may (may) be able to get away without the roughing bypass for the turbomolecular pump, and suck right through it. That may let you avoid the valves.

A humble glass Bell jar does the job in myriads of installations. The vessel is the easiest part here as the pressure differential is at most about 100 kPa.

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At -80k rpm, failure isn’t pretty.

The mid-sized glass bell jars used for vacuum that I’m thinking of cost over $1000.

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Anything with high energy inside, kinetic or electrical or potential, does not fall pretty. The failures aren’t pretty - they are often spectacular!

Count with it in the design. A steel outer housing, possibly reinforced with fiberglass, can do a good job. Calculate to catch the fragments. Look at photos on the net of failed centrifuges; these are illustrative to what to expect, though the heavy metal-block rotors pack quite more punch than a fairly lightweight “hedgehog” of blades.

The problematics here is the same as armor of tanks - something that stops fast projectiles and dissipates their energy before they get through. Into, in case of tanks, out of in case of fast-spinning rotors. The Killdozer guy made his own composite armor from steel plates and concrete. For tests, gun projectile can be considered a good “standard” as its weight and speed are quite well defined. You need a spallation liner on the outside, though. But that’s the easiest part.

Try these. Not sure how smaller they are but they are WAY cheaper.
http://www.thefind.com/appliances/info-bell-jar-vacuum

Also consider non-jar chambers.
http://www.abbess.com/vacuum/Economy-Vacuum-Chambers

These specific ones are designed for lower vacuum. However, the approach is solid; a metal housing with one side of glass. While the glass is flat, the calculations of thickness needed for the area/pressure differential are easy. Thick, laminated, “bulletproof” glass is also on the open market for prices that aren’t rock-bottom low but in smaller sheets are affordable.

Then you can go the more improvised way - I saw fusors made from a marmalade glass, and for a great number of setups that aren’t wider than its throat you can also use a round glass flask from a lab glass set. (If you are adventurous, you can build bigger stuff in using the approach of making ship models in bottles.)

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If you’re saying AQ was strong and the WTC were weak, then I guess so? But since that isn’t true, I have to say you’re just plain not correct about the meaning of those words.

Sorry you’re so upset about it. I’m probably on your side, just want you to use words so that they mean something.

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Like warfare for example? A terrorist attack is defined as not being war. And to be fair war usually requires a state actor.

A terrorist attack is not asymmetric warfare as a strategy. It can be guerrilla tactics though.

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No shit. Color me amazed.

There is one other issue, which is that running the roughing pump without a valve won’t work for higher vacuum than you can get with a roughing pump, because a large limiting factor is the vapor pressure of the pump oil. You need to seal it off before you can keep pumping down. Oilless roughing pumps exist, but they are much more expensive than valves.

I think it’s a great idea, it’s just that a lot of the relevant components haven’t been or can’t be subjected to the same cheapening of mind-boggling technology that’s happened in other areas.

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Assume you can find cheaper components. Not always a valid assumption but taking it as a default won’t stop you prematurely from examining options.

Both diffusion pumps and turbomolecular ones need running roughing pumps to maintain the lower-grade vacuum on their outlet side. The oil vapor pressure plays a role there but the high-vacuum stage pumps are there to prevent the further backflow.

Check e.g. this site, a homemade particle accelerator. Contains diagram of the used vacuum system, using a rotation oil-based pump as a roughing one, in tandem with a diffusion one.
https://www.youmagine.com/design_ideas/cheap-diy-miniaturised-uhv-system

I am not 100% certain about the necessity of the roughing valve. Todo: ask more knowledgeable ones why sucking air during the rough-pumping through the high-vac pump is not a good idea.

Sealed system, in contrary, is useful for getters and ion pumps. One of my thoughts for homemade vacuum tubes is an integrated ion pump in the standard assembly subset (so you can make jigs and the more repeated parts take less effort), with external magnet, so lower-grade cheaper system can be used for evacuating the vessel and the high-vacuum can be done later, and done repeatedly as the vacuum degrades by outgassing and minor leaks.

There’s a plethora of possibilities. See some speculations about one possibility here:
https://www.youmagine.com/design_ideas/cheap-diy-miniaturised-uhv-system

That’s exactly what should happen. I believe it is possible. There are few technologies that can’t be made cheap with manufacturing tech available today, and for them there should be alternatives. (Again, an assumption, but useful to not let you give up prematurely.)

There are vacuum hobbyists out there. Not as many as I would like, but quite some. Getting the costs down would do a great job in increasing their numbers.

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I mean, if I could get a vacuum chamber for a few hundred bucks, I’d be evaporating metal on everything.

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The chamber is easy(ish). The pump is the problem. For this purpose, check out how astronomers DIY-coat their mirrors with cheap vac-pumps. (Would one salvaged from a fridge, or an air-conditioning servicing one, be enough? A brief run of the evaporator would burn off the oxygen and nitrogen into solid deposits, and then there’s just the argon left that should not impair the deposition much…?)

Check out a DIY system here: http://lerch.no-ip.com/atm/
chapter 18 in the left menu, all the subchapters.

(Edit: thought: what about using induction heating instead of resistive, for the aluminium evaporation? Would eliminate the problems with the filaments.)

Also, don’t forget plasma etch before the metal deposition before coating plastics or it will not stick as well.

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Argon does impair deposition. The problem is not chemical reactions, it’s the metal atoms bouncing off other gas atoms.

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Qualitatively, definitely yes. But reactive removal of nitrogen and oxygen leaves only the two magnitudes lower pressure of argon, so the question is if the impairment would be enough to cause problems.

…also, could careful introduction of oxygen into the chamber at the end of deposition result in deposition of protective layer of alumina? (I know, I know, this is the CVD field…) What about using magnetron sputtering instead of evaporation, as that would actually require some argon around? (I know, I know, its own can of worms… but you could get mirrors from copper, gold, platinum, rhodium, palladium… and the ceramics, ohhhh, all the ceramics!)

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