Nuclear weapons for anti-missile defense

[etudiant]

etudiant,
Since you are essentially totally clueless on the subject; please refrain from making the pretense that you are informed, and don't mislead the denizens of the forum with false information.

Greg

Apart from aerospace, I make no claim to be informed beyond what I read in the news media and in the reports of congressional hearings.
Those sources have repeatedly stated that the Stewardship program is aimed to ensure the continued effectiveness of the US nuclear arsenal, not at improving its performance. The 2008 decision to abandon the Reliable Replacement Warhead program supports that view.
I would be thrilled to learn that the US has a vigorous and innovative nuclear energy initiative under way, but do not see substantial evidence of such an effort.

 

[Morbius]

Apart from aerospace, I make no claim to be informed beyond what I read in the news media and in the reports of congressional hearings.
Those sources have repeatedly stated that the Stewardship program is aimed to ensure the continued effectiveness of the US nuclear arsenal, not at improving its performance. The 2008 decision to abandon the Reliable Replacement Warhead program supports that view. .

etudiant,

100% WRONG AGAIN One of the provisions that authorized the development of the RRW was that it provided "no new military capability". The RRW was canceled purely on political grounds; it was canceled in 2007 when Nancy Pelosi became Speaker of the House, and no further provisions for funding RRW could be passed with Nancy Pelosi as Speaker. When Boehner became Speaker in 2011, the new Impediment became the President.

Evidently you harbor the mistaken idea that the purpose of the redesign / LEP process is to "improve performance". That is just NOT true - the purpose is to maintain the performance and safety.

Let me refer you to the following from the Associate Director of Lawrence Livermore responsible for the nuclear weapons program:

https://str.llnl.gov/Mar12/comMar12.html

WHEN the weapons comprising our nuclear forces of deterrence were originally designed decades ago, scientists knew the warheads could not remain safe, secure, and reliable indefinitely. Over time, components and materials deteriorate as the weapons age. As a result, the nuclear design laboratories—Lawrence Livermore, Los Alamos, and Sandia national laboratories—continually assess the health of the stockpile and determine whether a particular weapon type needs to undergo a life-extension program (LEP).

LEP efforts include identifying and correcting potential technical issues by refurbishing or replacing certain components. LEPs also allow us to strengthen existing safety systems, for example, by introducing insensitive high explosives, which are more resistant than conventional high explosives to detonation from fire or accident.

LEPs are an important tool that allows us to seamlessly sustain the nation’s nuclear weapons. In effect, LEPs are triumphs of the National Nuclear Security Administration’s (NNSA’s) Stockpile Stewardship Program, which was launched at the end of the Cold War to maintain our weapons without nuclear testing. Advances in science, engineering, and computing—representing everything we have learned about nuclear reactions and materials science for the past 70 years—are incorporated into LEP efforts to ensure the devices remain safer, more secure, more reliable, longer-lived, and more maintainable than ever.

Dr. Goodwin says it in the first paragraph of his commentary, that the nuclear weapons would not remain safe and reliable indefinitely.

Again, let me explain this in terms of an analogy. Have you ever heard of dynamite becoming "tender"? Dynamite was invented by Alfred Nobel, the founder of the Nobel Prize. Nobel made his fortune by solving a major industrial problem, which was that high-explosives like nitro-glycerin were extremely "touchy" and hard to handle. The "touchy" nature of "nitro" is legendary. Nobel found that if you mixed "nitro" with sawdust or a type of clay called "diatomaceous earth"; the mixture was more stable and easier to handle; but could still be detonated on command with Nobel's "blasting cap".

Unfortunately, dynamite didn't stay stable and safe to handle indefinitely. As dynamite aged, the "nitro" tends to separate from the sawdust or clay. You end up with a stick that has little pools of "nitro" or the "nitro" leeches into the paper wrapper. Once again, you have small volumes of pure "nitro" and that "nitro" is susceptible to shocks and bumps, and can be extremely dangerous to handle. If the dynamite is shocked or bumped, the little pools of liquid "nitro" can explode just as easily as if you had pure "nitro" because that is what you have, pure liquid "nitro". The explosion of that bit of "nitro" will then propagate and set off the explosion of the whole stick of dynamite. Essentially, the dynamite becomes as dangerous to handle as the original "nitro" from which it is made. When dynamite ages to this degree, it is called "tender".

http://en.wikipedia.org/wiki/Dynamite

Over time, the dynamite will "weep" or "sweat" its nitroglycerin, which can then pool in the bottom of the box or storage area. (For that reason, explosive manuals recommend the repeated turning over of boxes of dynamite in storage.)

If someone took dynamite that is approaching the dangerous "tender" stage and remixed and reformed the dynamite to reestablish its stable properties; would you call that "improving the performance" of the explosive? It's not improving on the explosive; it's reestablishing the safety margins that one had when the dynamite was first made.

In essence, the redesign / LEP process is NOT for improving performance; but to address problems that develop as the weapon ages, and even enhance the safety over the original specs. Note where Dr. Goodwin states, LEPs also allow us to strengthen existing safety systems, for example, by introducing insensitive high explosives, which are more resistant than conventional high explosives to detonation from fire or accident.

You seem to be stuck in this mindset that changes / modifications / redesign of nuclear weapons must be for the sole purpose of "improving the performance" ( "making a bigger bang" ). However, Dr. Goodwin's commentary above shows that not to be the reasoning. It is about sustaining the level of safety and reliability; or as the first sentence of the last paragraph of the quote above states:

LEPs are an important tool that allows us to seamlessly sustain the nation’s nuclear weapons

Greg

 

[nikkkom]

etudiant,

If you think about it, you will realize that the degree to which one can "direct" the shape of the nuclear explosion is to a far lesser degree than a chemical explosion because the "Q", the energy release of the reaction is so much greater for a nuclear explosion than a chemical explosion. The Q energy release is released isotropically, and the system, in essence, doesn't "remember" a direction.

For example, consider the scatter of a neutron off a light nucleus in comparison to the neutron-induced fission of a heavy nucleus. The scatter off the light nucleus can be significantly anisotropic because the system essentially "remembers" which direction the incident neutron was travelling. However, in the case of the fission, so much reaction energy is released isotropically that it "swamps" the incident energy of the neutron, and the fission reaction can be considered for all intents and purposes as isotropic.

IIRC at the temperatures involved (upwards of 100 million degrees) a large fraction of released energy exists in the form of photons (X-rays) - and those can be easily made to exit the casing anisotropically, by providing radiation windows with desired shapes.

 

[Morbius]

IIRC at the temperatures involved (upwards of 100 million degrees) a large fraction of released energy exists in the form of photons (X-rays) - and those can be easily made to exit the casing anisotropically, by providing radiation windows with desired shapes.

nikkom,

Only for an extremely short time. If, say you want to make a radiation beam that goes "downward", and you want to accomplish this by providing a metal casing that inhibits the radiation from going left / right, front / back or upwards; then in order for the casing to inhibit the radiation from going in those directions, it has to absorb that radiation. However, there's so much energy in a nuclear weapon that within an extremely short time, that casing will be heated to a plasma that can no longer absorb the radiation.

So your idea doesn't really work.

Greg

 

[nikkkom]

nikkom,

Only for an extremely short time.

Extremely short time is not a problem. X-rays move with the speed of light. That's very, very fast: 30 cm/nanosecond. Even if X-ray photon on average needs dozens of reflections before it finds the radiation window, it still takes just a few nanoseconds.

So, how many nanoseconds do we have?

If, say you want to make a radiation beam that goes "downward", and you want to accomplish this by providing a metal casing that inhibits the radiation from going left / right, front / back or upwards; then in order for the casing to inhibit the radiation from going in those directions, it has to absorb that radiation. However, there's so much energy in a nuclear weapon that within an extremely short time, that casing will be heated to a plasma that can no longer absorb the radiation.

The plasma does not need to absord the radiation. It is sufficient to reflect it. If the casing is made of high-Z materials, the plasma will stay opaque to the X-rays: they will be strongly scattered off it. This also means that not the entire casing turns to plasma at once - its inner few millimeters do so first, and then this plasma shields the rest for a short time.

That's exactly how second stage of fusion device works: high-Z lined casing keeps a "sea" of X-rays contained, so that they are used to ablatively compress the secondary. It works: radiation manages to compress the secondary before casing "burns through".

Nwfaq3 contains the following example:

"For example, after 100 nanoseconds at 2 KeV [~23 million K] the wave will have penetrated to a depth of 0.27 centimeters [of uranium]."

IOW: with reasonably thick casings (less than 1 cm) it is possible to contain X-rays long enough (hundreds of nanoseconds) for them to escape through radiation windows.

 

[Morbius]

Extremely short time is not a problem. X-rays move with the speed of light. That's very, very fast: 30 cm/nanosecond. Even if X-ray photon on average needs dozens of reflections before it finds the radiation window, it still takes just a few nanoseconds.

So, how many nanoseconds do we have?

nikkom,

You tell me. You are the one that wants an anisotropic source. I'm just saying that since any anisotropy is going to be extremely short lived, then for all intents and purposes, it didn't happen

The plasma does not need to absord the radiation. It is sufficient to reflect it. If the casing is made of high-Z materials, the plasma will stay opaque to the X-rays: they will be strongly scattered off it. This also means that not the entire casing turns to plasma at once - its inner few millimeters do so first, and then this plasma shields the rest for a short time.

100% WRONG! You don't get to decide whether the X-rays and gamma rays are going to reflect or be absorbed, Mother Nature makes that decision. Unfortunately for your hypothesis, reflection is a collective phenomenon of multiple atoms. However, the wavelengths of the high energy X-rays and gamma rays are too short; . That's why we don't have X-ray and gamma-ray mirrors modulo some relatively weak reflection at grazing angles for low energy X-rays.

TOTALLY 100% WRONG about the plasma "shielding". I can see you've NEVER studied plasma physics.

That's exactly how second stage of fusion device works: high-Z lined casing keeps a "sea" of X-rays contained, so that they are used to ablatively compress the secondary. It works: radiation manages to compress the secondary before casing "burns through".

Yes - I know how that works.
Gregory

 

[nikkkom]

nikkom,

You tell me. You are the one that wants an anisotropic source. I'm just saying that since any anisotropy is going to be extremely short lived, then for all intents and purposes, it didn't happen

I told it already. With 0.5 cm thick high-Z casing, we have several hundreds of nanoseconds before casing stops containing X-ray "photon soup".

100% WRONG! You don't get to decide whether the X-rays and gamma rays are going to reflect or be absorbed, Mother Nature makes that decision. Unfortunately for your hypothesis, reflection is a collective phenomenon of multiple atoms. However, the wavelengths of the high energy X-rays and gamma rays are too short; . That's why we don't have X-ray and gamma-ray mirrors modulo some relatively weak reflection at grazing angles for low energy X-rays.

There is no need to shout.

I didn't mean reflection as in a mirror. Scattering and re-radiation will do. And *it does* in the fusion device. High-Z plasma is opaque to X-rays. They get absorbed and re-radiated by it, impeding radiative energy transfer through casing.

TOTALLY 100% WRONG about the plasma "shielding". I can see you've NEVER studied plasma physics.

And also, each and every fusion bomb test is a fake. Right...

 

[Morbius]

I told it already. With 0.5 cm thick high-Z casing, we have several hundreds of nanoseconds before casing stops containing X-ray "photon soup".

nikksom,

Sorry - but your "calculation" is WAY, WAY TOO SIMPLISTIC. The physics is much more complex.

I didn't mean reflection as in a mirror. Scattering and re-radiation will do.

Scatter and re-radiation are NOT reflection. Heck you don't even know the vocabulary let alone how to do detailed calculations and simulation. When scientists mean scatter and re-radiation, they call it "scatter" and "re-radiation" and not "reflection".

And *it does* in the fusion device. High-Z plasma is opaque to X-rays. They get absorbed and re-radiated by it, impeding radiative energy transfer through casing.

This is where you don't know your plasma physics. High-Z solids are opaque, as are plasmas that have been compressed above what is called the "critical density". But EM radiation goes through plasma below the critical density. That's why I said it will only work the way you "think" it is going to work for an extremely short time. Not all the energy is re-radiated; and the energy that is not re-radiated is absorbed and turns the material from a high-Z solid to a high-Z low-density plasma that no longer has high opacity.

Enhanced x-ray emissions from low-density high-Z mixture plasmas generated with intense nanosecond laser

http://www.sciencedirect.com/science/article/pii/S0375960114000760

I would also recommend the classic text "Phyics of Fully Ionized Gases" by Lyman Spitzer.

And also, each and every fusion bomb test is a fake. Right...

By what stretch of "logical" reasoning did you come up with THAT?

Instead of discussing large "nuclear devices"; let's look at another topic which is ICF - Inertial Confinement Fusion. The re-radiation idea you espouse above is used in ICF. For example, I refer you to this Wikipedia entry:

http://en.wikipedia.org/wiki/Hohlraum

The indirect drive approach to inertial confinement fusion is as follows; the fusion fuel capsule is held inside a cylindrical hohlraum. The radiation source (e.g., laser) is pointed at the interior of the hohlraum, which absorbs and re-radiates the energy as X-rays, rather than on the capsule itself, a process known as indirect drive. The advantage to this approach is that the energy is re-radiated in a much more symmetric fashion than would be possible in the direct drive approach, resulting in a more uniform implosion.

The X-ray intensity around the capsule must be very symmetrical to avoid hydrodynamic instabilities during compression.

Gregory

 

[nikkkom]

nikksom,

Sorry - but your "calculation" is WAY, WAY TOO SIMPLISTIC. The physics is much more complex.

Okay. You are a specialist here, please start using numbers. I, a layman, already gave some numbers in my posts. Tell me which of my numbers are wrong. Give yours.

> And *it does* in the fusion device. High-Z plasma is opaque to X-rays. They get absorbed and re-radiated by it, impeding radiative energy transfer through casing.

This is where you don't know your plasma physics.

Indeed I'm not plasma physicist. However, I do know that fusion bombs use radiation implosion, that radiation for that purpose is contained by high-Z lined casing. It's public knowledge now. Am I wrong about that?

High-Z solids are opaque, as are plasmas that have been compressed above what is called the "critical density". But EM radiation goes through plasma below the critical density. That's why I said it will only work the way you "think" it is going to work for an extremely short time. Not all the energy is re-radiated; and the energy that is not re-radiated is absorbed and turns the material from a high-Z solid to a high-Z low-density plasma that no longer has high opacity.

Numbers please. How many nanoseconds plasma needs to expand to transparency after it gets heated by X-rays? I'm not asking you to reveal any secrets. Data from publicly-available sources such as NWFAQ will suffice.

 

[Morbius]

Okay. You are a specialist here, please start using numbers. I, a layman, already gave some numbers in my posts. Tell me which of my numbers are wrong. Give yours.

Indeed I'm not plasma physicist. However, I do know that fusion bombs use radiation implosion, that radiation for that purpose is contained by high-Z lined casing. It's public knowledge now. Am I wrong about that?

Numbers please. How many nanoseconds plasma needs to expand to transparency after it gets heated by X-rays? I'm not asking you to reveal any secrets. Data from publicly-available sources such as NWFAQ will suffice.

nikkom,

I am not commenting on anything in the NWFAQ.

I'm just saying that you aren't going to have some high-Z material stay opaque for 100 nanoseconds or more to provide your radiation "beam". In very short order, that is on very short time scales much, much less than your 100 nanoseconds ( 0.1 microsecond ); your high-Z material is going to be a low-density plasma that won't do what you think it is going to do.

Gregory

 

[nikkkom]

nikkom,

I can't comment on ANYTHING; even information that has been publicly released. I can't comment on anything in the NWFAQ.

I'm just saying that you aren't going to have some high-Z material stay opaque for 100 nanoseconds or more to provide your radiation "beam".

Okay. The numbers for fusion device I learned from public sources:

* generation of X-rays in 1st (fission) stage: ~50 nanoseconds.
* arrival of X-rays, thermalization of tamper and casing surface: 10 ns.
(As I told it before: X-rays move very fast!)
* ablative compression of the tamper and fusion fuel: 200-500 ns.
(you say it is impossible to contain X-rays for 100 ns)
* fusion burn: 20 ns.

It can be done. It *has been* done.

Compared to the above, our task doesn't even require X-rays to be contained for hundreds of nanoseconds. It appears the shape-forming casing needs to survive for only 10 ns or so.

 

[Morbius]

Okay. The numbers for fusion device I learned from public sources:

* generation of X-rays in 1st (fission) stage: ~50 nanoseconds.
* arrival of X-rays, thermalization of tamper and casing surface: 10 ns.
(As I told it before: X-rays move very fast!)
* ablative compression of the tamper and fusion fuel: 200-500 ns.
(you say it is impossible to contain X-rays for 100 ns)
* fusion burn: 20 ns.

It can be done. It *has been* done.

Compared to the above, our task doesn't even require X-rays to be contained for hundreds of nanoseconds. It appears the shape-forming casing needs to survive for only 10 ns or so.

nikkom,

In ICF, the fusion fuel is compressed by the X-rays from the laser drive.

Is the time it takes the fuel to move so that it is compressed necesarily equal to the time that the drive acts on the fuel?

Suppose I am playing baseball, and it takes 20 seconds for the ball that I hit to travel from home plate where I hit it, out to the left field foul post where it strikes the post. From that information, can we then conclude that the bat was in contact with the ball for 20 seconds when it got hit.
( Suppose I'm saying that it is impossible for the bat to maintain contact with the ball for 10 seconds )

That is EXACTLY the assumption you've made above when you compare compression times to the time that radiation is contained.

Gregory

 

[puncheex]

In the early 60s, before the PTBT went into effect, the Soviets did a number of such tests; they were wild about throwing their primitive missiles of the time up in trajectories of thousands of miles across their own territory, ending in nuclear blasts above Kazakhstan and Novaya Zemlya. The chief object was developing anti-missile technology. No other country (US included) ever played that loose. Only one time did the Soviets mess up - the test known as K-3 didn't make it to its intended target but exploded high over central Kazakhstan, and caused widespread EMP damage on the ground, reportedly burning down a power generation station.