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#300 by Danderman on 04 Sep, 2017 07:59
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This takes us back to the missile question.
We know that Hwasong 12 can fly 2,000 km, since it just did so, although the payload was unknown.
Hwasong 14, the "ICBM", is reported to be Hwasong 12 with a small upper stage to increase range at the expense of payload mass. It is not clear that Hwasong 14 could fly a conventional nuke payload very far, and we have no proof that NK has successfully miniaturized their bikes. -
#301 by RotoSequence on 04 Sep, 2017 08:09
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This takes us back to the missile question.
We know that Hwasong 12 can fly 2,000 km, since it just did so, although the payload was unknown.
Hwasong 14, the "ICBM", is reported to be Hwasong 12 with a small upper stage to increase range at the expense of payload mass. It is not clear that Hwasong 14 could fly a conventional nuke payload very far, and we have no proof that NK has successfully miniaturized their bikes.
A deterrent based on sabre rattling needs to be credible to be effective. -
#302 by randomly on 04 Sep, 2017 08:10
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A true fusion weapon is much more difficult to design than a fission weapon. I talked to the man who designed the first US fusion bomb Ivy Mike, his comment was "Fission bombs are easy, fusion devices are hard".
They actually do require more fissile material as there is a fissile "spark plug" at the core of the fusion portion of the weapon in addition to the fission core that provides the drive for the initial compression. The outer casing tamper can be made of depleted uranium and most of it will fission from the fast neutron flux from the fusion reaction inside. The outer casing can also be made of non-fissionable lead or some other material in which case the total device yield will be reduce to about 1/2. Something like 60% of the total energy typically comes from fission. There are limits to how big a yield you can get out of a pure fission or boosted fission weapon (around a megaton), however there is no limit on a fusion weapon. -
#303 by Star One on 04 Sep, 2017 11:10
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A true fusion weapon is much more difficult to design than a fission weapon. I talked to the man who designed the first US fusion bomb Ivy Mike, his comment was "Fission bombs are easy, fusion devices are hard".
They actually do require more fissile material as there is a fissile "spark plug" at the core of the fusion portion of the weapon in addition to the fission core that provides the drive for the initial compression. The outer casing tamper can be made of depleted uranium and most of it will fission from the fast neutron flux from the fusion reaction inside. The outer casing can also be made of non-fissionable lead or some other material in which case the total device yield will be reduce to about 1/2. Something like 60% of the total energy typically comes from fission. There are limits to how big a yield you can get out of a pure fission or boosted fission weapon (around a megaton), however there is no limit on a fusion weapon.
I thought there was a limit due to size. The Tsar bomb was impractically huge and not something that could be realistically used normally. -
#304 by ugordan on 04 Sep, 2017 11:16
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I thought there was a limit due to size. The Tsar bomb was impractically huge and not something that could be realistically used normally.
There's a limit to how big the subsequent stage can be compared to the primary (IIRC something like 100x the yield maximum), but in principle you can stack bigger and bigger thermonuclear stages. Tsar is believed to have been a 3 stage weapon, a fission primary powering a fusion stage and then that stage acting as primary for a 3rd stage. The U.S. has also tested three stage weapons.
Tsar was more about making a statement about Soviet weapon prowess than it being any kind of a usable weapon. -
#305 by Star One on 04 Sep, 2017 11:20
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I thought there was a limit due to size. The Tsar bomb was impractically huge and not something that could be realistically used normally.
There's a limit to how big the subsequent stage can be compared to the primary (IIRC something like 100x the yield maximum), but in principle you can stack bigger and bigger thermonuclear stages. Tsar is believed to have been a 3 stage weapon, a fission primary powering a fusion stage and then that stage acting as primary for a 3rd stage. The U.S. has also tested three stage weapons.
Tsar was more about making a statement about Soviet weapon prowess than it being any kind of a usable weapon.
Are Fusion devices in general much more difficult to miniaturise compared to fission devices? -
#306 by zubenelgenubi on 04 Sep, 2017 18:30
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Seeking a summation of the speculation in this thread:
Are we looking at a boosted-fission test?
(Increasing fission yield efficiency and simultaneously allowing miniaturization of a fission warhead via the inclusion of a small amount of fusile material?) -
#307 by Star One on 04 Sep, 2017 19:03
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Good summation here.
http://www.38north.org/2017/09/nuke090317/QuoteThe released photographs purportedly show Kim Jong Un providing “guidance” on what the North Korean press called a “thermonuclear” warhead for a ballistic missile. The device shown in the images has many of the hallmarks of such a device (two bulbous ends shaped like a peanut consistent with the claim of a “two-stage” device); however, caution should be taken as this is the conclusion that North Korea wants the US and others to reach from viewing the images and it is likely that an actual device will have a somewhat different design and that this was only a model mock-up.
QuoteRegardless of whether this most recent test was an operational warhead for an ICBM or simply a device, the yield of the test clearly shows North Korean progress in increasing the yields of the nuclear weapons. The significance of this is that it has the potential to dramatically increase the threat posed by its Strategic Force (responsible for ballistic missiles) as individual nuclear warheads potentially now have 10-times-greater destructive power. This would allow fewer missiles to be employed to ensure destruction of a given target, and increase the target set threatened by North Korean ICBMs by allowing a larger number of targets to be engaged with the current missile inventory. If the claim that the device just tested has a variable yield is true (from tens to hundreds of kilotons), then this would also imply a more sophisticated employment doctrine that envisions more limited, flexible and discrete targeting options than would otherwise be needed to implement a minimum deterrence, counter value doctrine.
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#308 by savuporo on 04 Sep, 2017 19:32
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Seeking a summation of the speculation in this thread:
Are we looking at a boosted-fission test?
(Increasing fission yield efficiency and simultaneously allowing miniaturization of a fission warhead via the inclusion of a small amount of fusile material?)
In the easy to digest version:
https://www.theguardian.com/world/2017/sep/03/did-north-korea-just-test-a-hydrogen-bomb
Seismic strength lends credibility to it being a h-bomb, but the telltale xenon signature hasn't been picked up by monitoring stations. Detection might be impossible though, if not much leaked out -
#309 by Star One on 04 Sep, 2017 19:37
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More to the post above.Quote
Stephen Schwartz @AtomicAnalyst
CTBTO has raised its body-wave magnitude estimate of DPRK's sixth nuclear test yesterday from 5.8 to 6.0, largest ever detected by the IMS.
https://mobile.twitter.com/AtomicAnalyst/status/904779901399470080 -
#310 by sanman on 04 Sep, 2017 22:11
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Potential launch dates coming up:Quote
G.Spezza @TheSpezz
Worth reminding: #NorthKorea has two of its most important anniversaries on Sep 9 & Oct 10. Expect more tests & missile launches. -
#311 by WulfTheSaxon on 04 Sep, 2017 23:05
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Do you think they will continue developing the weapons up to higher yields into the Megatons range, or is that likely to difficult or not needed for their purposes?
No, the focus will probably be on keeping size and weight down. They want to get the most out of what they have in terms of fissionable material and how big of a rocket they have to build. Tsar Bomba was impressive, but utterly useless in a real war.
I would think that, if anything, they would focus on improving prompt gamma ray production rather than total energy output (in order to maximize the EMP effect). Unfortunately, there’s no way to tell if they’re doing that. Hopefully the probable tunnel collapse after this latest test will at least reveal whether it was a hydrogen bomb. -
#312 by randomly on 05 Sep, 2017 03:16
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I thought there was a limit due to size. The Tsar bomb was impractically huge and not something that could be realistically used normally.
There may be a limit dictated by portability, but not a physical limit on the yield of the device as there is with a fission weapon. There is also a practical limit in that above 50-100 Mt the atmosphere above the explosion can't provide enough containment for the explosion and additional energy just blows the atmosphere above the explosion off. Increasing the yield above that point does not substantially increase the blast wave.
The USA no longer has any fusion weapons in their nuclear inventory. Only sub megaton boosted fission weapons, which are smaller in size and weight. Large weapons were only developed to compensate for poor delivery accuracy, which is no longer an issue. -
#313 by randomly on 05 Sep, 2017 03:30
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Are Fusion devices in general much more difficult to miniaturise compared to fission devices?
They are always larger than the smallest fission weapons, since it takes a fission weapon to power the second stage compression of the fusion core. -
#314 by Danderman on 05 Sep, 2017 06:09
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This takes us back to the missile question.
We know that Hwasong 12 can fly 2,000 km, since it just did so, although the payload was unknown.
Hwasong 14, the "ICBM", is reported to be Hwasong 12 with a small upper stage to increase range at the expense of payload mass. It is not clear that Hwasong 14 could fly a conventional nuke payload very far, and we have no proof that NK has successfully miniaturized their bikes.
A deterrent based on sabre rattling needs to be credible to be effective.
Those may be wise words, but that has nothing to do with the physical attributes of the Hwasong 14 missile.
Note that NK claims that its first satellite launch was successful, so their claims are not always credible. -
#315 by Star One on 05 Sep, 2017 07:32
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Are Fusion devices in general much more difficult to miniaturise compared to fission devices?
They are always larger than the smallest fission weapons, since it takes a fission weapon to power the second stage compression of the fusion core.
I thought this might be the case. I suppose with the way the regime seems to think that they will seek to develop up a megaton device. -
#316 by cn1984x on 05 Sep, 2017 07:55
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I thought there was a limit due to size. The Tsar bomb was impractically huge and not something that could be realistically used normally.
There may be a limit dictated by portability, but not a physical limit on the yield of the device as there is with a fission weapon. There is also a practical limit in that above 50-100 Mt the atmosphere above the explosion can't provide enough containment for the explosion and additional energy just blows the atmosphere above the explosion off. Increasing the yield above that point does not substantially increase the blast wave.
The USA no longer has any fusion weapons in their nuclear inventory. Only sub megaton boosted fission weapons, which are smaller in size and weight. Large weapons were only developed to compensate for poor delivery accuracy, which is no longer an issue.
B83 is over 1 megaton
W88 is Teller-ullam with a primary and secondary -
#317 by Hog on 05 Sep, 2017 14:59
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AgreedQuotethermonuclear warheads require less fissile material
They actually require a lot more, most of it in the tamper. Most of the energy in an H-bomb comes from fission, not fusion.
It's been a while since I've read up on Teller-Ulam staged thermonuclear combustion, but from what I remember that's not strictly true, at least in the sense that "fissile" usually implies self-sustaining fission.
Tampers, especially if you're not going for a "clean" bomb can be made of depleted uranium 238 which ought to be abundant to you since you're already either using natural uranium to produce smaller quantities of either Pu-239 or U-235. It doesn't have to be fissile by slow neutrons (self-sustaining fission, i.e. something you can make a bomb out of all by itself) to boost the yield up significantly by fast fusion neutron-induced fission. In this sense, tamper material shouldn't be a very scarce commodity.
Yes, in the secondary the neutron flux causes the U-238 tamper to grab a neutron and transmutate to Ne239, then Pu239. Of course all those fission products make things very very dirty. IIRC Tsar Bomba used a lead tamper to limit yield, of which approx. 90% came from fusion alone. But the 3 stage B-41 was more efficient on a mass/yield compare, the most efficient ever.
Much easier to make a chunk of U238(depleted Uranium) than a chunk of HEU235, from a cost/procurement standpoint. Though one is the byproduct of the production of the other.
Approx. 77% of the Ivy Mike device came from fast fission of the U238 tamper. the lack of U238 having a critical mass, means that you can stuff as much of the metal into the bomb as the secondary tamper as you wish.
The recent 50-100 kt test is impressive, and worrisome. They keep talking about a Hydrogen Device, but are the DPNK using a play on words here? Are these test subjects "simply" boosted fission devices with their focus soley on the Tritium (isotope of Hydrogen) that is usually injected into the core thus boosting the fission yield by using the powers of fusion(fusion of tritium and deuterium-both isotopes of Hydrogen- produces a neutron with an energy of 14 MeV)?
Or is North Korea really detonating true 2 stage Hydrogen weapons?
or
Are they demonstrating some sort of old school single stage device that uses large amounts of fusion fuel to cause a U238(depleted uranium) tamper to fission. Like the early Joe-4 and Soviet "Layer Cake" designs?
I guess the only real way of determining this would be by "sniffing" for the products of the test. Or by having the North Koreans actually tell us what they were doing, similarly like they did by telling the USA about the exact location of their U enrichment facilities by giving Siegfried Hecker a tour of their centrifuge enrichment building of the Uranium Enrichment Complex. (The famed one with the blue roof-which was doubled in size a few years ago.) With their Uranium enrichment centrifuge, in "full swing"(pun intended)and their Plutonium production reactor the 5MWe reactor firing back up, coupled with the success of a truly "fruitful" last test, the goal of miniaturizing some test subjects to fit them onto ballistic missiles is disconcerting to say the least. Even their last threat of an EMP strike would be "disruptive" at the very best.
Yesterdays emergency meeting of the UN in regards to DPRK. 6.0 magnitude up to 6.3 magnitude estimated yield 50-100 kt. The initial event was followed by a smaller event of which some scientists have speculated that the smaller event that occurred 8-1/2 minutes after the first event, was the test tunnel actually collapsing after the nuclear detonation.(I have seen reports of yield estimates that stretch up to 0.3 megatons or 300 kilotons.)
From a DPRK press release, actually two releases squished together by myself. They were released on the same day, August 3.
QUOTE "Their leader had inspected what they claimed to be a Hydrogen bomb which was conspicuously displayed in from of a Payload Fairing of a Hwasong-14 Inter-Continental Ballistic Missile "the Hydrogen Bomb was a multifunctional thermonuclear nuke with great destructive power which can be detonated at even high altitudes for super powerful EMP(electro magnetic pulse) attack"ENDQUOTE
All covered in this video of the 2nd emergency meeting about Nuclear Weapons Proliferation as it pertains to North Korea in less than a week
So the statement about the "Hydrogen Bomb" in front of their missiles Payload Fairing has obvious connotations.
We have the missile and a small enough nuke to place aboard said missile. IOW We have the weapon AND its delivery system.
I really hope their leader doesn't think that an EMP attack wouldn't have the same outcomes for him that an actual nuclear attack that would strike surface targets.
Here are the lofted trajectories of the last H-14 missile test. These trajectories were used to not encroach on other nations borders
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#318 by russianhalo117 on 05 Sep, 2017 15:19
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Anatoly Zak's analysis and response:
http://russianspaceweb.com/rd250.htmlQuoteThe RD-250 engine at the center of an international storm
In 2017, North Korea stunned the world with a series of test launches of long-range ballistic missiles. One popular explanation for the rogue state's remarkable progress in rocketry essentially blamed Ukraine for providing North Korea with know-how on the powerful RD-250 engine which bore some superficial resemblance to a North-Korean engine. But was it really possible, given the scale of effort required to reproduce and drastically redesign a complex rocket engine?
... -
#319 by Star One on 05 Sep, 2017 17:01
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Latest update on the yield of the sixth test.
US Intelligence: North Korea's Sixth Test Was a 140 Kiloton 'Advanced Nuclear' DeviceQuoteU.S. government sources with access to the latest intelligence regarding North Korea’s nuclear weapons program have told The Diplomat that its sixth nuclear test also involved an “advanced nuclear device.”
Per the early assessment shared with The Diplomat, the device was either a boosted fission device or, as North Korea claimed in its state media, a two-stage thermonuclear bomb. It’s unclear if the device test was the specific device North Korea showed in photographs prior to its test on Sunday.
http://thediplomat.com/2017/09/us-intelligence-north-koreas-sixth-test-was-a-140-kiloton-advanced-nuclear-device/