Eerie Rapatronic Nuclear Photographs:Taken Within 10 Nano-Seconds of Detonation

[19th LA Inf]

Sick looking, not something I want to spend much time looking at.

In the early 70s I was interested in developing a camera to photograph guided artillery rounds leaving the muzzle and shedding protective devices around their guide vanes. The idea I worked with was a first generation image intensifier, which employed 45 KV DC between the photocathode stage and the third intensifier photoscreen. The EEs were able to switch this HV on and off very quickly, on the order of a few microseconds. By simply photographing the screen with an ordinary film camera (before digital cameras) I could get a usable photograph. We found that the pulse from the grid current caused undesirable distortion in the image intensifier. Didn't have time or funds to pursue that problem. Just some hardware we had on hand.

Years earlier I had worked with an EG&G microflash strobe and Speed Graphic camera to study the formation of molten ammonium nitrate fertilizer pellets being sprayed into a cooling tower. Learned that Lord Rayleigh had done pretty much the same experiments peeking through holes in a spinning disk, 80 or 90 years earlier.

[Sequoyah101]

I had figured that the detonation was electrically initiated but wondered if the pulse would be fast enough to do that and trigger the camera. They didn’t have diodes but I guess they had capacitors to build delayed signals.

Pretty neat what can be done analog. Many hydraulic circuits have a high degree of programming in them with delays based on pressure pulses as event triggers.

[loungitude]

Can’t argue with that, however if the fiber reads detonation of the high explosive, there will be negligable x-ray production at that time.

[LaRueLaDue]

I’m just remembering this off the top of my head, so it might be somewhat inaccurate... Here goes:

One of the trickiest things that they had to develop to make the implosion device was a way to reliably trigger the spherical explosives at the right time and in the right sequence, so that the needed spherical implosion wave had the proper configuration. In the early bombs they had 32 points of detonation to trigger, making this a non-trivial task. They needed to coordinate the triggers within 10 nanoseconds (I think).

Anyway, this was way beyond what was commercially available at the time, so they developed their own triggering mechanism. They did so in the time needed (I think the triggers were only available mere weeks prior to the first test). The method used was an exploding bridgewire detonator, and was one of the most top secret parts of the whole endeavor. The work was done by Luis Alvarez and Lawrence Johnston.

I got most of this from the book by Richard Rhodes. Also, here is a link to a wikipedia article: https://en.wikipedia.org/wiki/Exploding-bridgewire_detonator

[rlmorel]

Ping

[Tijeras_Slim]

The time scale at which things occur in a nuke is amazing. Triggering of various data collection systems is calculated very precisely, and it doesn’t always work out perfectly.

I worked in the Nuclear test field in the early 90’s when we were conducting the final tests. There was one fiberoptic instrument that I was aware of (having worked on it a bit), but it was never fielded prior to the end of testing.

[Sequoyah101]

The entire story is absolutely astounding isn’t it?

The story also goes that development of the B-29 was an undertaking of similar magnitude though I find that hard to believe.

Hanford works alone had 50,000 laborers at one time and most had no idea what they were building.

I knew a guy from a town in Western Oklahoma that was nabbed right after he graduated as an electrical engineer from OAMC. They put him on the group responsible for provision of electrical power grids at Los Alamos and told them if the power ever went out they would all be dead. Probably a little drama there.

[loungitude]

Not arguing, but always curious, see:
The United States has been the world leader in HEMP technology since the first articles on the subject appeared in the early 1960’s. These scientific papers appeared in the open literature, which allowed the Soviet Union to become active in the field. The general consensus is that Soviet (now Russian) capabilities lag years behind those of the United States. Nonetheless, Soviet interest in pulsed-power, which began under A.D. Sakharov, should call attention to the possibility that some of the Soviet HEMP program was very closely held. HEMP capabilities have been acquired by the European nations, including Sweden and Switzerland. Many of these countries have developed active programs that include the use of simulators operating nearly at the threat level. Papers presented at recent unclassified conferences by participants from the countries of the former Warsaw Pact indicate that they lag significantly behind the West in both simulation and theoretical understanding. Several foreign vendors produce equipment comparable to that available from U.S. sources. France manufactures pulse generators, field sensors, fiber-optic links, transient digitizers, and measurement systems; England manufactures 1-GHz band-width fiber-optic links used mainly in HEMP and conducts high-power microwave research. Switzerland and Israel have also developed test/simulation equipment of high quality.
Source:
http://www.fas.org/nuke/intro/nuke/test.htm

Yup the stuff goes fast. Please see

http://nuclearweaponarchive.org/

If you are not already familiar with it.

Thanks for the input!

[PreciousLiberty]

Hey, those are some very interesting pictures. I’ve long been interested in nuclear phenomenology.

I do need to point out, though, that those are 10 nanosecond exposures, not images taken 10 nanoseconds after detonation. At 10 ns. after detonation, the fireballs could have been no larger than about 10 feet in diameter. Those are considerably larger. :-)

[GeronL]

almost looks alien

[ADemocratNoMore]

Bttt - Thanks for posting.

[ColdOne]

Thanks for posting.

[logi_cal869]

From the teams at Lookout Mountain Laboratory.

Thanks for the post.

[Ozark Tom]

Light travels slightly less than 1 foot per 1 nano(billionth) second. Electrical impulse through wires is considerably slower due to magnetic induction and electrical capacitance effects slowing transmission of a signal.

One variant of a thyratron was sensitive to light, so a sudden shift to a sufficient light level would trigger operation and switch electrical flow through a high voltage transformer.

The output of the high voltage transformer was used to initiate a short circuit between the contacts of the trigatron, a type of switch, placed between the capacitor bank and the coil of the shutter device.

The discharge pulse of the capacitor into the wire transmission line would reach a camera’s shutter and trip an exposure. The longer the distance from a capacitor to a camera, the longer the time delay until an exposure occurred.

Arrange cameras at properly chosen time intervals dictated by propagation delay along a single transmission line, or multiple parallel transmission lines of different length all synchronized by the firing of a single thyratron, and sequential photos can be captured.

[lbryce]

Thanks for the Times story.

[Bob]

I’d think that an electronic circuit triggered by the detonation signal would delay the camera shutter firing to occur at a specific time after the bomb was detonated. With multiple cameras triggered at different delays, a time sequence of the explosion could be captured.

[Sequoyah101]

I really wondered if they had not used some kind of light sensitive switch. That would make the most sense.

[21twelve]

Cool photos of the blast. From another thread a few weeks ago; a link to a “TED” talk on “femtophotography” at 1 trillion frames per second. Pretty amazing what has transpired in 60 years.

http://www.ted.com/talks/ramesh_raskar_a_camera_that_takes_one_trillion_frames_per_second.html

[LaRueLaDue]

Yeah, the B-29 work needed to get the platform able to drop the bomb reliably and get people back was quite extensive. They had essentially rushed the B-29 into service before it was ready, and Tibbits had to redo a lot of their testing work and modification recommendations, including making the bomb bay doors larger to accommodate the size of the weapons.

Think of Oak Ridge in addition to Hanford. The sheer size of these sites and the number of people involved, and that they were able to keep most of this under wraps was just amazing.

I grew up in Los Alamos (many years afterward) and it is small potatoes compared to Hanford and Oak Ridge.