SD.Net World Redux Comment Thread IX

[RogueIce]

Hey PeZook, my P-3s belong to the Navy. So that squadron commander would be a Commander, and the command pilot a Lieutenant or Lieutenant Commander.

[PeZook]

Hey PeZook, my P-3s belong to the Navy. So that squadron commander would be a Commander, and the command pilot a Lieutenant or Lieutenant Commander.

Right. Stupid anglosaxon ranking schemes

I'll correct it right away.

[RogueIce]

Right. Stupid anglosaxon ranking schemes

I'll correct it right away.

If they were Air Force it'd be ok, since I totally use the USAF officer structure for the SRAF. But the Navy is the Navy.

[Steve]

Stas, after asking Marina about it I have to conclude that your proposed thermonukes as described are not technologically feasible and so are nixed from the game.

I will listen to a defense of them, however.

[Fingolfin_Noldor]

Stas, after asking Marina about it I have to conclude that your proposed thermonukes as described are not technologically feasible and so are nixed from the game.

I will listen to a defense of them, however.

We would like to know the reasons first. Some of us do not regard Marina particularly technologically well versed in many things.

Plus, has she even read the papers in question, or just some pop sci crap?

[Steve]

The figures used were related to her in the discussion. But if you have another authoritative view on the technology I'm willing to hear it.

[The Duchess of Zeon]

Stas, after asking Marina about it I have to conclude that your proposed thermonukes as described are not technologically feasible and so are nixed from the game.

I will listen to a defense of them, however.

We would like to know the reasons first. Some of us do not regard Marina particularly technologically well versed in many things.

Plus, has she even read the papers in question, or just some pop sci crap?

I was never given any papers to read, so the fact that there were some rather than this being something that Stas made up for the game is now highly irritating for me to find out after I gave an opinion based on my own current understanding of nuclear processes. I am, alas, only as good as the data initially provided.

Can someone rectify this, please?

[Steve]

Okay, y'know what, I've apologized for getting Marina dragged into this. But the fact is that the instant I read that Stas post I was very uncertain it would fly and I wanted to make sure of things before I made any statements. I brought up Marina's name because of her knowledge and it being generally known. I shouldn't have.

So let's keep this in house. If Stas or Fin or whomever can give me a full explanation of the basis for their development and why it would work in our world setting, I will consider it, but going on what I've seen so far this project isn't actually possible, at least in the way it's being claimed (portable thermonukes and such).

[The Duchess of Zeon]

Okay, y'know what, I've apologized for getting Marina dragged into this. But the fact is that the instant I read that Stas post I was very uncertain it would fly and I wanted to make sure of things before I made any statements. I brought up Marina's name because of her knowledge and it being generally known. I shouldn't have.

So let's keep this in house. If Stas or Fin or whomever can give me a full explanation of the basis for their development and why it would work in our world setting, I will consider it, but going on what I've seen so far this project isn't actually possible, at least in the way it's being claimed (portable thermonukes and such).

It's well known that I don't know shit yet. Call me back in five years and I'll be an expert on applied nuclear engineering issues, with some luck. Not right now.

[Fingolfin_Noldor]

You can start by reading this: Ultra-dense deuterium: A possible nuclear fuel for inertial confinement fusion (ICF)

[Sea Skimmer]

A laser ignition system for a fusion bomb would require power higher then that to be produced by ITER…. scaled down enough to fit into the bomb casing. I’ll leave it to you guys to decide how feasible you think doing that before 2200 would be. Don’t forget to consider how totally worthless all air power and artillery will become in the event anyone has laser technology that good. Heck at that point a infantrymen might reasonably well have a turret on his helmet that vaporizes rifle bullets and hand grenades in mid flight.

[K. A. Pital]

Yeah, basically ultra-dense deuterium is regarded as the (possible) ideal ICF fuel, which can be ignited with laser-ignition only without the need for fission detonators. Knowing that inertial confinement is at the forefront of nuclear weapon miniaturization efforts, and understanding the implications of possible laser ignition, it is natural to assume UDD to be the ideal nuclear weapon material. If anyone has objections of fundamental nature (i.e. "cannot be contained in principle" or something like that), I am all ears.

However, if those objections are "that can't be because UDD is only being created now" or "that is powergaming", that I'm not willing to hear.

The MESS professed to employ miniaturized net-energy producing fusion reactors on ships a decade from now. How realistic is that? How realistic are the "wideband stealth" claims, which were repeatedly brought up by me as bad game practice, since "wideband" stealth can only be "wideband" in terms of an aircraft's shape, but shape alone cannot reduce the RCS to the levels of stealth that material coating allows in the select bands, hence performance in various bands would be very uneven and hence would not give the same level of 'stealth' against a multi-band radar, making the term "wideband stealth" an intellectually dishonest trick.

Same here. I call for impartial judgement on feasibility, but if not, we're going to employ tech workarounds. And I'm being quite honest here that we don't want to simply copycat the MESS who are re-creating just about every single abandoned and active U.S. future weapons program, and one (indigenous) way to do that is to increase the potency and usability of our nuclear arsenal. That may not sit well with folks, but objections have to be of scientific nature.

EDIT: Oh, okay. Laser power it is then? How feasible would that be to solve with, say, fast fusion?

[The Duchess of Zeon]

Ironically the objection I gave to Steve was exactly idenitcal to Sea Skimmer's objection.. Which means I don't withdraw that objection, not even after reading the article. It is realistic in theory, but not practically weaponizable with 20th - 21st century technology.

Well, let me further amend that. It might be... But it would yield no advantage over a regular nuclear weapon due to the bulkiness of the lasers required, and their expense and fragility. And the expense and fragility of the capacitors.

[Fingolfin_Noldor]

The worst case scenario is go back to using a fission starter. Either way, the bomb is still heck a lot smaller.

Well, let me further amend that. It might be... But it would yield no advantage over a regular nuclear weapon due to the bulkiness of the lasers required, and their expense and fragility. And the expense and fragility of the capacitors.

Pulse lasers do not rely on capacitors. They rely on an active medium such as Electro-Optic Modulators or Acoustic Optic Modulators or passive mediums such as saturable absorbers.

And by the way, Femtosecond lasers have been known to be fiber based and thus very compact.

[K. A. Pital]

Yeah, in the worst case we'll go back to fission-induced explosions. Not such a great revolution as expected, but still something.

As for lasers: http://www.laserfocusworld.com/articles/325414. This is pretty compact by modern standards of laser power (a very intense 30 fs pulse).

Or this: "This highly efficient Nd:YAG laser was designed as a prototype NASA-funded transmitter for space-based LIDAR missions. This design completed a 4.8 billion shot lifetest at 242 Hz with 10-15 mJ pulses and 10 ns pulsewidth."
http://www.opticsinfobase.org/abstract. ... 005-JTuC24

That shit is very, very compact, and HiPER fast-fusion chamber would use 70 kJ pulses with ~ ps durations. This performance in practice can be duplicated if what I'm reading is correct. As far as I gather, picosecond is less than a nanosecond, so pulse power can go up while time goes down.

I still await principal explanations why this would not work to which technical solutions would not exist. Yes, perhaps the stress on laser components is something that cannot be discounted, but in that case, lasers would only be used in weapons that do not have stress issues (like pre-placed mines). The rest would use fusion igniters. Not as beautiful, but still enormous volume gains.

P.S. http://cddis.nasa.gov/lw13/docs/papers/ ... ova_1m.pdf
It appears that this is roughly within the required ballpark of both energy, duration and compactness, and it has been created.

P.P.S.
http://scitation.aip.org/getabs/servlet ... s&gifs=yes
Femtosecond pulses can ignite deuterium fusion - if i'm not reading something wrong.
http://www.russia-ic.com/education_scie ... rough/767/
Compact PW-fS laser. That is quite a little overpowered for the job if fast fusion a-la HiPER does work. As far as I gathered, unlike currently considered fuels, UDD has nigh perfect density for initiating reactions, meaning the compression phase can be foregone and only the "fast ignition" pulse is required.

Of course, there are problems with making enough UDD and storing it
http://www.phys.unsw.edu.au/STAFF/VISIT ... PBsing.pdf
If someone can claim (I don't have enough authority here) that storing pellets of UDD is unfeasible in principle not even in 10 years time from now, I'm not going to object.

[Ryan Thunder]

Stas, after asking Marina about it I have to conclude that your proposed thermonukes as described are not technologically feasible and so are nixed from the game.

I think its hilarious that we're talking about technological feasibility when Lonestar has a motherfucking vampire in his armed services as a special agent and is resurrecting people.

[K. A. Pital]

HERV was injected into the game by Marina as means to... um... make it more interesting? I don't have an issue with Lonestar's vampires.

Me and Fingolfin thought of a military and scientific invention that would be relevant but not too outlandish. After all, something should change since we're moving away from short term "fiction" to midterm fiction by hitting post 2020 years.

If needed I can try to my best to make the necessary calculations on the required energy of fs laser pulses.

[Steve]

Well, I certainly congratulate you on imagination, Stas, I just wasn't convinced it was feasible in this timeframe. Maybe later on... if we get that far.

As I've mentioned to a couple of people, I think that between the need to fine tune the game rules and deal with the problem of steadily heading into speculation on tech advances we should start talking about letting this game go, declare our characters the winners in Q's eyes or whatever and start work on SDN World 3, well, if anyone's up for it. I mean, not now, but when it's clear enough people are ready to move on and no longer interested in this game.

Anyway, I think that while the idea is sound there are a few questions about the feasibility at the scale announced. Though if you think you can finetune things go ahead, we'll look over the math and such.

[K. A. Pital]

Okay, I'll look into the necessary calculations.

http://arxiv.org/PS_cache/physics/pdf/0 ... 0071v5.pdf
Meanwhile, this paper suggests that even Deuterium-Tritium pellets would be feasible as sub-kiloton weapons and detonation source because only compression requires high-energy lasers while ignition requires high power lasers and may be achieved with as little as 1 kJ powerful subpicosecond pulse, which is within realm of tabletop modern superlasers; the only question then would be the prohibitive cost of munitions since their firing would result in the destruction of a high-powered laser. But then, with mass production of such lasers, the cost may be lowered.

[MKSheppard]

A laser ignition system for a fusion bomb would require power higher then that to be produced by ITER…. scaled down enough to fit into the bomb casing. I’ll leave it to you guys to decide how feasible you think doing that before 2200 would be.

Or even if the laser system scales up correctly to larger yields without an appreciable growth in the laser and it's energy storage system.

I mean, 5 grams of Li-6 Deuteuride in metallic form (320 tons at 100% efficiency) is about 9cm3; if we wanted a megaton of force at 100% efficiency, you'd need 15,625 grams; or 7,500 cm3. Lasers being light and cheap enough to fuse the 9cm3 target might become impossibly large when faced with a 7,500 cm3 target.

I actually can see something like this working, to replace SADMs or MADMs; where you need to blow up a dam or important bridge, and want to avoid nasty groundburst fallout. Ideally, you'd charge the capicators in the device from a gas turbine generator or whatnot at your Forward Operating Base, strap the device to it's own parachute attached to you by a lanyard; and parachute out over the target within a few hours.

Reason I say within a few hours, is all energy storage systems' lose power, and I can't see a capacitor cheap AND light enough to be expended having a very good energy retention capability.

You can get 64 kt/kg out of Lithium-6 Deuteride assuming a 100% efficient fusion reaction. If we assume it's only 10% efficient; that's 6.4 kt/kg, and if we work this around a 5 gram pellet of Li-6, that's about 32 tons of explosive force.

If we go all the way down to just 2% efficient, we can still pack the force of a 6.4 ton bomb in something weighing only a couple hundred pounds.

Jesus, can you imagine the havoc being wrought by SPETSNAZ operators carrying 6 ton bombs on their backs? With six tons of explosives, a lot of things that were formely difficult from a military engineering stand point become a lot easier -- can you imagine placing a booby trap just outside a MESS military barracks that when the MESS guys come swarming out, they trip the laser tripwire, and trigger the 6 ton bomb?

[PeZook]

That's supposed to be the primary use, though, isn't it? Explosives light enough to fit on missiles too small for full-scale nukes, and still expanding their destructive potential beyond anything chemical explosives can achieve.

[K. A. Pital]

I mean, 5 grams of Li-6 Deuteuride in metallic form (320 tons at 100% efficiency) is about 9cm3

1cm2 of Rydberg matter ultradense deuterium (and we're assuming in 10 years our engineers figured out how to produce UDD in one of those states of Rydberg matter where it's long-lived) is 140 kg.

Lasers being light and cheap enough to fuse the 9cm3 target might become impossibly large when faced with a 7,500 cm3 target.

15,625 grams of UDD would be a pellet so tiny that a tabletop superlaser pulse could do the job; or at least I presumed so. I may be mistaken. And tabletop femtosecond pulse lasers do exist now, so I logically assumed miniaturization in 10 years would finally achieve the capability to pack something like that into at least a missile warhead or shell.

[MKSheppard]

That's supposed to be the primary use, though, isn't it?

IIRC, the original annoucement was something like "fit into cluster bombs" or something like that. While that could be achievable, I can't see it with our level of tech. Like skimmer said, perhaps in 200 years....

Explosives light enough to fit on missiles too small for full-scale nukes, and still expanding their destructive potential beyond anything chemical explosives can achieve.

Take for example the SS-21. Normally, it would have only 120 kg of HE; but if you put a crude laser ignition system into it; which you could fit into the 0.65m diameter; you could achieve a 6-10 ton warhead on that little thing.

[K. A. Pital]

I would like to note that I calculated the required energy intensity basing on HiPER fast-fusion calcs and the claims of the UDD investigators that it's density does not require a compression stage, only ignition, and that FS duration pulses can ignite a fusion reaction.

The intensity would be ~10^20 W/cm2 (HiPER-like ignition with a single, one-sided pulse), I presumed that the pulse would last several femtoseconds.

This is possible with tabletops.
http://www.princeton.edu/mae/people/fac ... _new_type/

Hope I didn't screw up.

[Shroom Man 777]

Guys, I'll be disappearing for the next two weeks for out of town NUERSING.

Um, but after that I guess I will no longer have any out of town NUERSING. So, after that, we can finally get cracking on PRIME NOIR, PeZooks!

(Please wait up for me!)