The effects of nuclear weapons. Credible nuclear deterrence, debunking "disarm or be annihilated". Realistic effects and credible nuclear weapon capabilities for deterring or stopping aggressive invasions and attacks which could escalate into major conventional or nuclear wars.

Tuesday, April 11, 2006

Teak and Orange, each 3.8 Mt (50 % fission) detonated at 77 and 43 km altitude

Above: Teak photographed from Hawaii, 1 minute after detonation 1,300 km away, 1 August 1958, a 3.8 Mt burst at 77 km directly over Johnston Island. On the left hand side a faint aurora from the base of the radioactive fireball shows the path of radiation travelling along the earth's magnetic field towards the southern hemisphere. The missile was supposed to detonate 32 km southwest of the island, but malfunctioned and detonated directly over the island, but the thermal exposure at ground zero was only 1.0 cal/sq cm, too low for skin burns, but adequate to dazzle 6 people standing outside the control shelter (see clip in this film). Anyone looking directly towards the detonation would have received retinal burns to the eyes at ground zero, and the safe distance for watching the Teak fireball without goggles was 725 km.

Glasstone and Dolan explain: 'Because the primary thermal radiation energy in a high-altitude burst is deposited in a much larger volume of air, the energy per unit volume available for the development of the shock front is less than in an air burst. ... The air at the shock front does not become hot enough to be opaque [so] ... There is no apparent temperature minimum as is the case for an air burst. ... the thermal radiation is emitted in a single pulse ... The reason is that formation of ozone, oxides of nitrogen, and nitrous acid, which absorb strongly in this spectral region, is decreased [because these chemicals, which give the fireball its rust-like colour and create the thermal minimum by absorbing fireball radiation until the shock front breaks away from the fireball and cools, only form in a dense, compressed shock wave].'

This spectacular midnight event made the front page of the 1 August 1958 Honolulu Star-Bulletin:

'I stepped out on the lanai and saw what must have been the reflection of the fireball. It turned from light yellow to dark yellow and from orange to red. The red spread in a semi-circular manner until it seemed to engulf a large part of the horizon. A cloud rose in the center of the circle. It was quite large and clearly visible. It remained visible for about a half hour.'

Above: 'For shot Teak there was a single [ultraviolet] pulse lasting a few tenths of a second. Most of this energy came from molecular emission bands rather than from the blackbody radiation common to surface or near-surface bursts. The infrared radiation was intense but brief - about 2.5 sec in duration. The maximum radius of the infrared fireball was almost 20 miles. The thermal pulse from shot Orange showed some of the characteristics of a sea-level shot. There was some evidence of a minimum and a second maximum. Some of the energy was radiated in a continuous spectrum, in addition to spectral bands similar to those from Teak. The infrared emission lasted about 18 sec, and the infrared fireball radius reached a maximum of about 15 miles.'

- Report of the Commander, Operation Hardtack, Task Group 7.1, weapon test report WT-1382, May 1959, page 43. (Available in two versions, with different deletions, here and here.)

Page 44 of this report says the atmospheric transmission of thermal radiation (infrared) vertically to ground zero for Teak was 63%, and a lot of Teak's fireball radiation was in the ultraviolet which was absorbed by the ozone layer (90% of this ultraviolet was received within 0.175 second), but for Orange atmospheric transmission to ground zero was only 6% owing to 'deteriorating weather conditions' (cloud cover).

Above: Johnston Island in 1958 (page 16 of WT-1682), showing the angular land runway and missile launch complex (which was expanded in 1962 for the final high altitude tests), the surrounding shallow water covered reef, and the dredged lagoon area constituting the seaplane landing strip. The actual island labelled on this map covered an area of 175.4 acres. (Shown to the north east of the main island is Sand Island, which is much smaller.)

The U.S. Department of Defense book by Glasstone and Dolan states:

'The Teak explosion was accompanied by a sharp and bright flash of light which was visible above the horizon from Hawaii, over 700 miles away. Because of the long range of the X rays in the low-density atmosphere in the immediate vicinity of the burst, the fireball grew very rapidly in size. In 0.3 second, its diameter was already 11 miles and it increased to 18 miles in 3.5 seconds. The fireball also ascended with great rapidity, the initial rate of rise being about a mile per second. Surrounding the fireball was a very large red luminous spherical wave, arising apparently from electronically excited oxygen atoms produced by a shock wave passing through the low-density air.

'At about a minute or so after the detonation, the Teak fireball had risen to a height of over 90 miles, and it was then directly (line-of-sight) visible from Hawaii. The rate of rise of the fireball was estimated to be some 3,300 feet per second and it was expanding horizontally at a rate of about 1,000 feet per second. The large red luminous sphere was observed for a few minutes; at roughly 6 minutes after the explosion it was nearly 600 miles in diameter.' - Glasstone and Dolan, 1977.

The radioactive debris from Teak reached an altitude of 500 km in 20 minutes. At this time, 20 minutes after detonation, a complete blackout of MF and HF radio occurred across the South Pacific, New Zealand and Australia because 30% of the high speed ionised fission product debris spiralled along the magnetic field lines from the burst point in the northern hemisphere (Johnston Island) into the southern hemisphere.

As previously pointed on on this blog, Teak produced an intense EMP at ground zero which was not measured locally (due to an EMP prediction error made by Dr Bethe and instrument failures), but the distant, late-time EMP was detected 3,200 km away at the Apia Observatory at Samoa: ‘sudden commencement’ of a magnetic disturbance four times stronger than any recorded due to solar storms, followed by a visible aurora along the earth’s magnetic field lines (A.L. Cullington, Nature, vol. 182, 1958, p. 1365).

We have already discussed the radiation belts produced by high altitude bursts, which damage satellites and pose a danger in low earth orbit and also affect skywave radio. In the case of Teak, there were no satellite failures because 1958 was still the infancy of Sputnik (although 3 satellites failed and another 3 were damaged after Starfish in 1962).

But radio communications on all frequencies below 1 MHz were blacked out for 3 days after Teak (LA-6405). Even at HF, the 10 MHz Japan to Honolulu radio link suffered a massive 40 decibel attenuation of signal strength for 6 hours following Teak. LA-6405, page 21 states that for Teak: 'The prompt gamma-ray output was high, nominally 0.2% of yield'. (For comparison, Russian's reported that their 300 kt missile carried test on 22 October 1962 had a prompt gamma ray output of 0.13%, while the figure from America data for 1.4 Mt Starfish is 0.10%. The American manual EM-1 by Dolan states that in a 100% fission thin-cased weapon the figure can be as high as 0.5%.) On page 18 the author, Herman Hoerlin (at Johnston Island when Teak was detonated) writes that all communications at Johnston Island were shut off from America for hours after Teak:

'One of the first transmissions actually received at Johnston Island in the morning hours after the event was: "Are you still there?" Honolulu had serious difficulties in maintaining air travel services. Indeed, they had to be suspended for many hours because of the failure of long-wave communications.' The 2002 publication Defense's Nuclear Agency 1947-1997 (AD-A412977) gives some more information about Teak and Orange on pages 140-2:

'One observer, an Air Force lieutenant watching the sky around midnight that evening from his porch, recalled TEAK: "... it seemed to be a semi-circular fireball on the horizon... I just thought it was Honolulu or Pearl Harbor and I was dead." The Apia Observatory [which measured the auroral EMP or perhaps the MHD-EMP to be 4 times stronger than any due to solar flares] in Western Somoa approximately 2,000 miles to the south described the "... violent magnetic disturbance," which heralded "... the most brilliant maifestation of the Aurora Australis [Southen Lights} ever seen in Somoa." The resulting persistent ionisation of the low-density atmosphere cut high frequency communicatios with New Zealand for six hours. ... At the AFSWP's [Armed Forces Special Weapons Project; now the Defense Threat Reduction Agency] offices in the Pentagon, Admiral Parker grew concerned for the personnel on Johnston Island as hour after hour passed with no word regarding the test. Finally, some eight hours after TEAK had occurred, the word that all was well came ... The communications blackout worried others as well. Later AFSWP learned that one of the first messages received at Johnsto Island once communications was restored was: "Are you still there?". ...

'The Army Redstone crew returned to Johnston Island to make final preparations at the launch pad for ORANGE. During the evening of August 11, the missile was launched. When it reached 125,000 feet, the fire signal was sent to the missile with no apparent response. Someone had failed to throw a safety switch once the missile had cleared the island's safety zone. Technicians quickly discovered and corrected the error, though the Redstone reached 141,000 feet before detonating. ORANGE's yield was equal to the TEAK shot, but [owing to the lower altitude of burst, 43 km versus 76.8 km] less spectacular. ... One observer on the top of Mount Haleakala on Maui described the [ORANGE] display as "... a dark brownish red mushroom [that] rose in the sky and then died down and turned to white with a dark red rainbow." While ORANGE was visible for about 10 minutes in Hawaii, it had little effect on radio communications.'

A few details of the success of the ABM missile defence aspects of Teak and Orange have been released in one of the declassified versions of WT-1382.

Report of the Commander, Operation Hardtack, Task Group 7.1, weapon test report WT-1382, May 1959, pages 40-41:

'Project 8.6 had as its objective the obtaining of information concerning weapon outputs and corresponding structural effects during high altitude detonations of nuclear weapons. The data would be useful in evaluating the effectiveness of nuclear warheads as the energy source for destruction of an incoming ICBM. A jettisonable instrumented pod was affixed to each of theTeak and Orange Redstone missiles. The pods, ejected prior to burnout, were placed in close proximity to the device at burst time and were designed to be recovered. A two-stage parachute system slowed water entry to prelude hydrodynamic impact damage, and varied devices were installed on the PM to facilitate its location. After a 10-hr daylight search by air and surface craft the hunt for the Orange pod was abandoned, and no data were recovered. Recovery was successful on Teak, however, and there appeared to be large thermal X-ray induced mechanical impulses of even greater intensity than had been predicted. These impulses are capable of producing structural failures, as evidenced by the severe damage incurred by the front instrument casing of the pod. There was no evidence to support the existence of an X-ray shadow (region of low intensity) along the longitudinal axis of the Teak device. The X-ray induced impulses on lead, zinc, iron, copper, and aluminum were appreciable at the… estimated slant range of 23,000 ft. The beryllium sample was not affected.'

Report of the Commander, Operation Hardtack, Task Group 7.1, weapon test report WT-1382, May 1959, page 42:

'Project 4.1, supported by thermal measurements from Project 8.1, studied the limiting distances at which chorioretinal burns might be caused by very high altitude detonations. Rabbits were exposed to shots Teak and Orange at stations located on Johnston Island, aboard ships, and in aircraft. It was found that a very high altitude burst is particularly effective in producing chorioretinal burns because of the rapidity with which thermal radiation is delivered … The limiting horizontal distance at ground level for minimal [exposed retina] burns was found to be 300 nautical miles for Teak… The size and severity of the lesion correlated with distance. Correspondingly greater limiting distances would apply if the exposure was at altitudes where there would be proportionally less atmospheric attenuation. All burns produced within 160 nautical miles would have produced permanent injury or at least a segmented visual defect in man. Visual acuity would have been reduced to from 20/100 to 20/200 if the lesion should occur on the macula.'

Above: Orange, toroidal yellow or orange coloured fireball and white-blue-green-purple air radiation induced glow photographed from an aircraft (first photo) and from the deck of a U.S. aircraft carrier (second photo) at 1 minute after burst, 12 August 1958, Johnston Island. (No photographs could be taken from Johnston Island due to local cloud cover, so the only photos existing were taken from ships and aircraft.)

This test caused a beta radiation aurora in the other (i.e., southern) hemisphere, which was observed from Apia, Samoan Islands, over 2,000 miles from Johnston Island, lasting 17 minutes. The aurora was due to the motion along the earth's magnetic field of beta particles (electrons), emitted by the radioactive fission fragments. Like Teak, Orange used a W-39 warhead carried by a Redstone missile: 'Purpose was to measure the effects of high altitude nuclear explosions in order to design warheads for Nike-Zeus anti-ballistic missile system.'

This image and caption is available in black and white as Fig 1 of Herman Hoerlin's United States High Altitude Test Experiences, Los Alamos National Laboratory's report LA-6405, 1976, and in colour on the Atomic Weapons Establishment's website, and is one of the most spectacular images of the cold war. Orange produced a thermal flash exposure of 3.0 cal/sq cm at ground zero, not enough to cause fires, but enough to cause serious eye retina heating and permanent damage for anyone watching the fireball at night without welder's goggles.

Above: Orange at 1.0 second

Above: Orange at 2.0 seconds

Above: Orange at 3.0 seconds; the rocket exhaust trail can be seen near the bottom.

Orange main flash peaked within just 0.15 second, much less than for an equivalent low altitude burst. Most of the radioactive debris gradually rose to 150 km altitude, causing a HF radio blackout across the Pacific which began 5.25 hours after detonation and lasted for 2 hours, with signal degradation continuing for another 2.75 hours after that. LF and MF blackout (below 1 MHz) lasted for a whole day after Orange. The 1962 Bluegill bomb test was fairly similar to Orange because the altitude of detonation was only slightly greater. Orange debris fallout was tracked very successfully because the bomb was 'salted' deliberately to produce 3 megacuries of a special radionuclide, Rh-102 (isomer half life: 210 days), so it could be specifically distinguished - by analysis of the energy spectrum of the fallout radiation - from fallout contributions caused by other tests. There is no local fallout, and a great deal of decay occurs before any distant fallout descends. (The radiation levels are small compared to background produced by cosmic rays, naturally radioactive potassium-40, natural uranium, radon, etc., which is far more intense.)

In all bomb bursts where a spherical hot air fireball is produced, it becomes buoyant after expanding because once the pressure falls to ambient pressure, the great temperature implies that the air density is low. Therefore, it has buoyancy, just like a hot air balloon. The spherical fireball naturally turns into a toroidal shape (a horizontal ring doughnut) as it rises, due to air drag on the top and periphery and the faster updraft of very hot air through the centre. The hotter air rising in the middle (1) emerges at the top, (2) collides with the air above because the fireball is rising rapidly, and (3) is deflected sideways and then downwards by the air pressure due to the rapid rate of rise, and so the hot air from the middle of the fireball cascades over and around the fireball, down the periphery or outer edge, so that it is distorted into a ring shape.

For a detonation on the ground or water, dust and water vapour will enter the fireball and are contaminated to produce contaminated particles or salt-slurry raindrops of fallout. These condense from vapour to liquid and solid when the fireball rises, expands and cools. For air bursts in humid Pacific air, you do not get any local fallout but you do get moist air being entrained and condensing to form a visible white cloud if the detonation occurs below about 10 km altitude.

However, for high altitude bursts like Orange, there is no material present except the bomb and missile vapours and the dry very low-density air. Hence, no visible mushroom cloud occurs. But the beta and gamma radiation penetrates great distances with minimal attenuation, initiating fluorescent reactions like those produced by solar nuclear radiations which cause natural auroras around the Earth's poles.

Previous high altitude test discussions:

Checkmate photos and effects studies here and here
Starfish and its EMP measurements and effects studies, including recent arguments (and EMP from Russian 1962 tests)
here and here

Argus and the major 1962 high altitude tests Kingfish and Bluegill will be discussed later.

Update: The DVD called Nukes in Space: the Rainbow Bombs (Narrated by William Shatner), contains an interview comment by Dr Byron Ristvet of the U.S. Defense Threat Reduction Agency who states that either the 1958 Teak or Orange shot caused unexpected EMP induced power cuts on Oahu in the Hawaiian Islands:

'As it was, one of those two high altitude shots [Teak and Orange, August 1958] did affect the power grid on Oahu, knocking out quite a bit of it. That was unexpected.'

Oahu is 71 km long by 48 km wide, and power cables could have picked up significant EMP, especially the MHD-EMP effect caused by fireball expansion. However, this is surmise. Why is the U.S. Defense Threat Reduction Agency being coy over their EMP effects data? Which test did this? Why not say "Teak knocked out part of the power grid on Oahu"? Why secrecy?

Another example: the sanitized report ITR-1660-(SAN), Operation Hardtack: Preliminary Report, Technical Summary of Military Effects Programs 1-9, DASA, Sandia Base, Albuquerque, New Mexico, 23 September 1959, sanitized version 23 February 1999.

On page 347 of ITR-1660-(SAN), the first American measurement of high altitude EMP was made not at Starfish in 1962 (which Dr Conrad Longmire claimed), but at the 2 kt Yucca test in 1958. (The Teak shot EMP measurements failed because the shot went off directly overhead instead of 20 miles downrange due to a missile guidance error.) They only measured the beta ionisation which affects radio/radar transmissions for hours, but it is the brief high frequency EMP which causes physical damage to equipment. Although Yucca was of too low yield to cause EMP damage, oscilloscopes in 1958 did record the intense, high frequency magnetic dipole EMP mechanism which caused the damage in the higher yield (1.4 Mt) Starfish test of 1962:

'Shot Yucca ... [EMP] field strength at Kusaie indicated that deflection at Wotho would have been some five times the scope limits... The wave form was radically different from that expected. The initial pulse was positive, instead of the usual negative. The signal consisted mostly of high frequencies of the order of 4 Mc, instead of the primary lower-frequency component [electric dipole EMP] normally received ...'

Another EMP cover up story - which comes from Glen Williamson who was on Kwajalein when Starfish was tested - is that the first surface burst in Nevada in 1951 (test Sugar) coupled EMP out of cables from the bomb to the control point, and on to the main power supply, then beyond it to Las Vegas, tripping circuit breakers:

'Right after WWII, during one Nevada test, circuit breakers, 90 miles away [Las Vegas], were tripped; thus giving early hints of EMP.'

Notice that there is some evidence of something like this in extracts from B. J. Stralser's 30 April 1961 EG&G Secret - Restricted Data report Electromagnetic Effects from Nuclear Tests. Prevous Nevada tests were aircraft dropped free air bursts with no close-in cables to couple EMP into equipment. As soon as cable-controlled Nevada testing started, they found EMP returning in the cables would get into other circuits by cross-talk (i.e., mutual inductance, Ivor Catt's alleged area of excellence).

After the first bad EMP event in 1951, they switched over the Nevada Test Site's telephone system to run off diesel generators at shot times, to avoid EMP getting into the U.S. power grid. The Stralser report states that at the main power supply, 30 miles (50 km) from the detonation, technicians were warned over the loudspeaker system prior to each shot:

'Stand by to reset circuit breakers.'

Stralser also reports that protective measures like carbon block lightning protectors proved useless at the Nevada against the EMP from the cables: the EMP was so severe it would simply 'arc over' the power surge arrestor. Lead-tape shielded cables at out to 800 metres from Nevada tests with yields below 75 kt had their multicore conductors fused together by the heat of carrying thousands of amps of EMP current! The full Stralser report is unavailable at present, only a brief extract and summary of it can be found in the U.K. National Archives at Kew, in an originally 'Secret - Atomic' note (the British equivalent of the American 'Secret - Restricted Data' classification). The file is a British Home Office Scientific Advisory Branch report on the effects of nuclear detonations on communications technology. Dr R. H. Purcell was the chief scientific advisor in the Home Office at that time, and apparently he wrote the summary for the benefit of his scientists because it was of too high classification for them to see the full American report. A few years later, the summary was published - without the source (Stralser) report being disclosed - in the Home Office Scientific Advisory Branch magazine Fission Fragments.


At 4:22 pm, Blogger nige said...

From: Jack Reed
To: Nigel B. Cook
Sent: Monday, June 26, 2006 6:08 PM
Subject: Blogs and memories

Hi Nigel, I was amazed last night when I got around to visiting your blog site. Obviously, you're no beginner at studying nuclear weapons and technology. Much of the stuff there I was not particularly familiar with, but several items brought back old memories and faces. Thanks. Is your intent to put together a book?

Your collection of info on the Japanese and Rongelap radiation survivors was interesting to me, having had some accidental exposures totalling around 64 R, with only 4 R on an official film badge. A few years ago United States support for the Japanese survivor studies was cut off, to my chagrin. Later I inferred the reason. One of their reports claimed that of 47,000 being tracked after 40-100 R exposures, they were now dying - at one-quarter the rate of their unexposed controls. My conclusion: politically unacceptable to the American anti-nukes. Now, later figures show 3/4 of my veteran colleagues of WW-II are dead, so we (40-100 R) have been "vaccinated". Neat!

The other stong recollection was about that Teak cloud. Some twenty minutes after the shot, I spotted a white "smoke ring" in the NW sky, from the deck of the carrier USS Boxer. Back to my home office, I did the calculation of the closest point where it could be in the sun (01:00 Johnston Island time). I haven't easy access to my old files and forget the exact numbers, but that required a SE wind of around 1500 knots. My colleague, Hugh Church, then did the calculations for the hydrostatic winds around the hot, low pressure area under the direct sun, and came up with nearly the same wind direction and speed. We submitted these two reports to the J. Geophysical Research, and received prompt rejection because "everyone knew that the circulation at those ionospheric altitudes was dictated by the electric field." Some twenty years later, your Sir James Lighthill published a report based on neutral particle flow at such altitudes, because only a tiny fraction of the air was ionized and of no consequence. Hugh and I never got around to re-submitting our articles, but I did get to meet Lighthill at an Oxford meeting in 1985, and told him that chuckler. And finally, in 2003, I got to face a 93-year-old James Peoples, later-long-time-editor of Science Magazine and previously editor of the JGR. His response was "I am a chemist, and I had to rely on my advisors for such problems". More chuckles.

Straight Ahead, Jack W. Reed
And reed that boweth down to euery blaste. Chaucer, 1385

I believe in getting into hot water. I think it keeps you clean. G.K.Chesterton

----- Original Message -----
From: Nigel B. Cook
To: Jack Reed
Sent: Sunday, June 25, 2006 3:29 AM
Subject: Blast yield estimates controversy QQQQ

Hi Jack,

Many thanks for these comments on using the EMP to give the time of detonation in 1955 Teapot tests. I've been reading the sanitized report ITR-1660-(SAN), "Operation Hardtack: Preliminary Report, Technical Summary of Military Effects Programs 1-9", DASA, Sandia Base, Albuquerque, New Mexico, 23 September 1959, sanitized version 23 February 1999.

It contains a lot of blast data including a plot of all the Pacific data for very low overpressure blast, in Fig 6.13 on page 287, and also seems to refer to a report of yours concerning thermal radiation effects on page 453:

J. W. Reed and others, "Thermal Radiation from Low-Yield Bursts", Project 8.8, Operation Hardtack, ITR-1675, January 1959, Air Force Cambridge Research Centre, Laurence G. Hanscom Field, Bedford, Massachusetts, Secret Restricted Data.

One issue with thermal radiation is that some reports say it varies with yield. Did you find any evidence of this? Glasstone 1962/64 suggests that the thermal yield fraction for a surface burst varies from 1/7 or 14% for Nevada tests to 1/4 or 25% for Pacific tests. Brode's 1968 RAND Corp report on computer simulations indicates that the thermal yield fraction theoretically increases with bomb yield.

The fireball radius at second thermal brightness, when most radiation is emitted, scales up more rapidly (radius proportional to W^0.4) with yield than the blast pressure that greates nitrogen dioxide that shields some of the thermal radiation (radius proportional to W^1/3). Therefore, you would expect nitrogen dioxide in the shock wave to filter out more of the thermal radiation in a low yield burst than a high yield burst. This accounts for the rise in predicted thermal yield with yield in air bursts.

In a surface burst, the cratering action does much the same thing, throwing up a dirt over a radius that scales as the cube-root of yield, so it should have a greater shielding effect on the fireball radiation at maximum brightness at low yields than high ones. So the thermal fraction again should increase with increasing yield.

It is very hard to see how energy is really used in a nuclear explosion. Glasstone 1950 claimed that only about 1% is used in cratering and ground shock, but that was based on a theory that air blast caused both effects. Brode's 1960 RAND computer simulation showed the figure was 15% because the case shock of the bomb is denser than the air shock and couples far better to the ground. C. E. Adams of USNRDL in a 1958 report calculated that 3% of the energy in the Redwing-Inca tower shot was used for melting the observed mass of fallout. Report DNA 5159F-1 (1979) on simulations of mushroom cloud rise (for the main U.S. Department of Defense DELFIC fallout computer) states on page 12:

"On the basis of considerable experience with the cloud rise model we take the fraction of explosion energy used to heat air, soil and water to their initial temperatures to be 45% of the joule equivalent of the total yield, W."

This is a massive amount of energy, essentially the entire blast yield. Hence about 15% of the energy of the surface burst nuclear explosion is used in ground shock and cratering, 45% in mushroom cloud rise, and over 3% in melting fallout. This accounts for 63% of the explosion energy without mentioning nuclear radiation, blast or thermal!

But if you look at chapter 1 of Glasstone and Dolan, it says 50% is blast, 35% is thermal, 15% nuclear.

So there is really a total lack of accounting for the energy, and I think Glasstone and Dolan is severely misleading. The blast wave at high overpressures is losing energy very rapidly by heating up the air it engulfs. Therefore, it is a complete fiction to quote 50% blast yield. They get it by subtracting the thermal and nuclear yield from 100%, but clearly the blast wave is continuously leaving warm air behind and thus losing wave energy.

My calculations at indicate that the blast wave begins with all the available fireball energy, 85% of the explosion energy, and then loses energy as the overpressure falls until it has only about 1.09% of the explosion energy when it has become basically a sonic wave at great distances. Therefore, the idea that the blast contains 50% of the energy is entirely misleading. It starts with 85% or so, and then loses energy by thermal radiation from the surface and from leaving behind hot air which rises to form the cloud, etc., until the energy is dow to 1.09% of the total.

On page 347 of ITR-1660-(SAN), the first American measurement of high altitude EMP was at the 2 kt Yucca test in 1958. The Teak shot EMP measurements failed because the shot went off directly overhead instead of 20 miles downrange due to a missile guidance error. They only measured the beta ionisation which affects radio/radar transmissions for hours, but it is the brief high frequency EMP which causes physical damage to equipment: "Shot Yucca ... [EMP] field strength at Kusaie indicated that deflection at Wotho would have been some five times the scope limits... The wave form was radically different from that expected. The initial pulse was positive, instead of the usual negative. The signal consisted mostly of high frequencies of the order of 4 Mc, instead of the primary lower-frequency component normally received ..."

Best wishes,

----- Original Message -----
From: Jack Reed
To: Nigel Cook
Sent: Sunday, June 25, 2006 4:51 AM
Subject: Re: Electrical effects at the Nevada Control Point? QQQQ

Hi Nigel,

>I cannot understand how the EMP effect was kept secret until 1961.<
I didn't ever realize that it was, particularly after the high altitude Teak shot in 1958 disrupted communications over most of the Pacific. I was somewhat familiar with it and used the pulse in 1955 to give our distant (200 km) microbarograph operators a shot time on their paper recordings. We simply hung a hundred meters or so of copper wire to catch it, for the vast Nevada areas didn't have very reliable telephone contacts and we hadn't gotten an off-site radio system yet. Before that, in 1953 when I read in Scientific American about ham operators getting radio whistlers from lightning, I suggested in a report (that was classified at the time) that USSR nuclear tests could be easily detected at the southern conjugate in the Indian Ocean. I never got a response from the report, but 3-4 years later a navy man told me they were doing such monitoring with a pair of ships on site rotation from Western Australia. Again, I should have applied for a patent. That leads to another story.

Also, ca 1953-4, a Scientific American article described extremely bright flashes in laboratory shock tubes filled with argon. As a long-time member of the 188th Fighter Squadron, New Mexico Air National Guard, I published another classified report, "An Aircraft Psychological Defense Device", proposing flare-sized clear plastic shock tubes filled with argon to pop out when an enemy fighter got on your tail. The flash should stun him long enough to make an escape maneuver. The Air Force had different ideas, however, as such dog-fights became obsolete, and used argon shock devices to light up Viet Nam in night-time surveillance.

Anyway, I wasn't involved in general instrument maintenance in the immediate test areas and didn't pay much attention to their problems nor read all the various reports that came out. My concern was weather dependences - distant airblast and fallout - and I never was much interested in electricity.

Straight Ahead, Jack W. Reed
And reed that boweth down to euery blaste. Chaucer, 1385

I believe in getting into hot water. I think it keeps you clean. G.K.Chesterton

----- Original Message -----
From: Nigel Cook
To: Jack Reed
Sent: Wednesday, June 21, 2006 4:04 AM
Subject: Electrical effects at the Nevada Control Point? QQQQ

Hi Jack,

Thank you very much for setting the facts straight on the sound being associated with the first peak, taking a few milliseconds. All of the film tracks of blast waves sound more like hurricane winds, than bangs.

Since you were at the control point if - assuming it is not secret - you recollect EMP effects. I cannot understand how the EMP effect was kept secret until 1961. ...


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