Thermonuclear weapon
The Teller-Ulam design is a nuclear weapon design which is used in megaton-range thermonuclear weapons, and is more colloquially referred to as "the secret of the hydrogen bomb". It is named after two of its chief contributors, Hungarian physicist Edward Teller and Polish mathematician Stanisław Ulam, who developed the design in 1951. The idea is generally thought to pertain specifically to the use of a fission bomb "trigger" placed near an amount of fusion fuel, known as "staging", and the use of "radiation implosion" to compress the fusion fuel before igniting it. There are a number of other additions and variations to this idea posited by different sources, outlined below.
The first device to be based on this principle was detonated by the United States in the "Ivy Mike" nuclear test in 1952. In the Soviet Union, this design was known as Andrei Sakharov's "Third Idea" (similar devices were developed by the United Kingdom, France, and China as well, though no specific code name is known for their designs).
Basic principle
The basic principle of the Teller-Ulam configuration is based upon the idea that different parts of a thermonuclear weapon can be chained together in "stages" which allow for the full detonation of each. At a bare minimum, this implies a primary section which consists of a fission bomb (a "trigger"), and a secondary section which consists of fusion fuel. Because of the "staged" design, it is thought that a tertiary section, again of fusion fuel, could be added as well, based on the same principle of the secondary. The energy released by the primary compresses the secondary through the concept of "radiation implosion", at which point it is heated and undergoes nuclear fusion.
The primary is thought to be a standard implosion method fission bomb, though likely with a core boosted by small amounts of fusion fuel for extra efficiency. When fired, the plutonium and/or uranium-235 core would be compressed to a very small sphere by special layers of conventional high explosives arranged around it in a lens pattern, initiating the nuclear chain reaction that powers the conventional "atomic bomb".
The secondary is usually shown as a column of fusion fuel and other components wrapped in many layers. Around the column is first a "tamper", a heavy layer of unenriched uranium-238 which serves to help compress the fusion fuel (and may eventually undergo fission itself). Inside this is the fusion fuel itself, likely a form of lithium deuteride. This dry fuel, when bombarded by neutrons, produces tritium, a heavy isotope of hydrogen which can undergo nuclear fusion, along with the deuterium present in the mixture. (See the article on nuclear fusion for a more detailed technical discussion of fusion reactions.) Inside the layer of fuel is the sparkplug, a hollow column of fissile material (plutonium or uranium-235) which, when compressed, can itself undergo nuclear fission (it can apparently have more than a critical mass in a hollow column configuration). The tertiary, if one is present, would be set below the secondary and probably be made up of the same materials. (Hansen 1988 and 1995)
The basic idea of the Teller-Ulam configuration is that each "stage" would undergo fission or fusion (or both) and release energy, much of which would be transferred to another stage to trigger its own firing. How exactly the energy is "transported" from the primary to the secondary is not completely known, but is thought to be transmitted through the X-rays which are emitted from the fissioning primary. This energy is then used to compress the secondary, though whether this happens because of the radiation pressure exerted by the X-rays, or because the X-rays create a plasma in an intervening medium (a polystyrene plastic foam), remains unclear.
The sequence of firing the weapon (with the foam) would be as follows:
- The high explosives surrounding the core of the primary fire, compressing the fissile material into a supercritical state and beginning the fission chain reaction.
- The fissioning primary emits X-rays at the speed of light, which "reflect" along the inside of the casing, irradiating the polystyrene foam (see below for a note on what "reflection" means in this context).
- The irradiated foam undergoes a phase transition, becoming a hot plasma, pushing against the tamper of the secondary, compressing it tightly, and beginning the fission reaction in the sparkplug.
- Pushed from both sides (from the primary and the sparkplug), the lithium deuteride fuel is highly compressed and heated to thermonuclear temperatures, and begins a fusion reaction.
- The fuel undergoing the fusion reaction emits a large flux of neutrons, which irradiates the uranium-238 tamper (or the uranium-238 bomb casing), begins to itself undergo a fission reaction, providing about half of the total energy.
This would complete the fission-fusion-fission sequence. Fusion, unlike fission, is relatively "clean"—it releases energy but no harmful radioactive products or large amounts of nuclear fallout. The fission reactions though, especially the last fission reaction, release a tremendous amount of fission products and fallout. If the last fission stage is omitted (by replacing the uranium tamper with one made of lead, for example), the overall explosive force is reduced by approximately half but the amount of fallout is relatively low.
A number of possible variations have been proposed:
- The aforementioned means of transferring the energy from the primary to the secondary, either by means of raw radiation pressure from the X-rays or their use in creating a plasma in a medium of polystyrene foam.
- Either the tamper or the casing have been proposed as being made of uranium-238 for the final fission stage.
- In some descriptions, additional internal structures exist to protect the secondary from receiving excessive neutrons from the primary.
- The inside of the casing may or may not be specially machined to be specially created to "reflect" the X-rays. X-ray "reflection" is not like light reflecting off of a mirror, but rather the reflector material is heated by the X-rays, causing the material to itself emit X-rays, which then travel to the secondary.
Two special variations exist which will be discussed in a further section: the cryogenically cooled liquid deuterium device used for the "Ivy Mike" test, and the putative design of the W88 nuclear warhead—a small, MIRVed version of the Teller-Ulam configuration with an oblate (egg or watermelon shaped) primary and an elliptical secondary. Most bombs do not apparently have tertiary stages — the U.S. is thought to have only produced one such model, the massive 25 Mt B-41 bomb[1], and the Soviet Union is thought to have used multiple stages in their 50 Mt Tsar Bomba. If any hydrogen bombs have been made from configurations other than those based on the Teller-Ulam design, the fact of it is not publicly known, with the possible exception of the Sloika design discussed below.
In essence, the Teller-Ulam configuration relies on at least two instances of "implosion" occurring: first, the conventional (chemical) explosives in the primary would compress the fissile core, resulting in a fission explosion many times more powerful than that which chemical explosives could achieve alone. Second, the radiation from the fissioning of the primary would be used to compress and ignite the secondary, resulting in a fusion explosion many times more powerful than the fission explosion alone. This chain of compression could be then continued with an arbitrary number of secondaries, and would end with the fissioning of the natural uranium tamper (something which could not normally be achieved without the neutron flux provided by the fusion reactions in the secondary). Such a design can be scaled up to an arbitrary strength, potentially to the level of a doomsday device (though usually such weapons are not more than a dozen megatons, which is generally considered enough to destroy even the largest practical targets).
History
Teller's "Super"
The idea of using the energy from a fission device to begin a fusion reaction was first proposed casually by the Italian physicist Enrico Fermi to his Hungarian physicist colleague Edward Teller in fall of 1941 during what would soon become the Manhattan Project, the World War II effort by the United States and United Kingdom to develop the first nuclear weapons. Teller soon was a participant at Robert Oppenheimer's summer conference on the development of a fission bomb held at the University of California, Berkeley, where he guided discussion towards the idea of creating his "Super" bomb, which would hypothetically be many times more powerful than the yet-undeveloped fission weapon. Teller assumed creating the fission bomb would be nothing more than an engineering problem, and that the "Super" provided a much more interesting theoretical challenge.
For the remainder of the war, however, the effort was focused on first developing fission weapons. Nevertheless, Teller continued to pursue the "Super", to the point of neglecting work assigned to him for the fission weapon at the secret Los Alamos lab where he worked (much of the work Teller declined to do was given instead, it turns out, to Klaus Fuchs, who was later discovered to be a spy for the Soviet Union). Teller was given some resources with which to study the "Super", and contacted his friend Maria Göppert-Mayer to help with laborious calculations relating to opacity. The "Super", however, proved elusive, and the calculations were incredibly difficult to perform, especially since there was no existing way to run small-scale tests of the principles involved (in comparison, the properties of fission could be more easily probed with cyclotrons, newly created nuclear reactors, and various other tests).
After the atomic bombings of Japan, many scientists at Los Alamos rebelled against the notion of creating a weapon thousands of times more powerful than the first atomic bombs. For the scientists the question was in part technical—the weapon design was still quite uncertain and unworkable—and in part moral: such a weapon, they argued, could only be used against large civilian populations, and could thus only be used as a weapon of genocide. Many scientists, such as Teller's colleague Hans Bethe (who had discovered stellar nucleosynthesis, the nuclear fusion which takes place in the sun), urged that the United States should not develop such weapons and set an example towards the Soviet Union. Promoters of the weapon, including Teller and Berkeley physicists Ernest Lawrence and Luis Alvarez, argued that such a development was inevitable, and to deny such protection to the people of the United States—especially when the Soviet Union was likely to create such a weapon themselves—was itself an immoral and unwise act. Still others, such as Oppenheimer, simply thought that the existing stockpile of fissile material was better spent in attempting to develop a large fleet of atomic weapons rather than potentially squandered on the development of a few massive "Supers". (Galison and Bernstein 1989)
When the Soviet Union exploded their own atomic bomb (dubbed "Joe 1" by the U.S.) in 1949, it caught Western analysts off guard, and President Harry S. Truman ordered a crash program to develop a hydrogen bomb in early 1950. Many scientists returned to Los Alamos to work on the "Super" program, but the initial attempts still seemed highly unworkable. In the "classical Super", it was thought that the heat alone from the fission bomb would be used to ignite the fusion material, but this proved to be impossible. For awhile, many scientists thought (and many hoped) that the weapon itself would be impossible to construct.
Ulam's idea
The exact history of the Teller-Ulam breakthrough is not completely known, due in part to numerous conflicting personal accounts and continued classification of documents which would reveal which was closer to the truth. Previous models of the "Super" had apparently placed the fusion fuel either surrounding the fission "trigger" (in a spherical formation) or at the heart of it (similar to a "boosted" weapon) in the hopes that the closer the fuel was to the fission explosion, the higher the chance it would ignite the fusion fuel by the sheer force of the heat generated.
In 1951, after still many years of fruitless labor on the "Super", an innovative idea from the Polish émigré mathematician Stanisław Ulam was seized upon by Teller and developed into the first workable design for a megaton-range hydrogen bomb. The exact amount of contribution provided respectively from Ulam and Teller to what became known as the "Teller-Ulam design" is not decidedly known in the public domain—the degree of credit assigned to Teller by his contemporaries is almost exactly commensurate with how well they thought of Teller in general. In an interview with Scientific American from 1999, Teller told the reporter:
- I contributed; Ulam did not. I'm sorry I had to answer it in this abrupt way. Ulam was rightly dissatisfied with an old approach. He came to me with a part of an idea which I already had worked out and difficulty getting people to listen to. He was willing to sign a paper. When it then came to defending that paper and really putting work into it, he refused. He said, "I don't believe in it." (Stix 1999)
None of Teller's Los Alamos colleagues, though, agreed with this assessment. Bethe gave Teller "51%" of the credit for the creation of the H-bomb, while other scientists (those more antagonistic to Teller, such as J. Carson Mark) have claimed that Teller would have never gotten any closer without the assistance of Ulam and others, in particular because he had spent so much time explicitly arguing against the approach to the design that Ulam ended up taking. (Rhodes 1995)[2][3]
The Teller-Ulam breakthrough—the details of which are still classified—was apparently the separation of the fission and fusion components of the weapons, and to use the radiation produced by the fission bomb to first compress the fusion fuel before igniting it. Some sources have suggested that Ulam initially proposed compressing the secondary through the shock waves generated by the primary, and that it was Teller who then realized that the radiation from the primary would be able to accomplish the job (hence, "radiation implosion"). But compression alone would not have been enough and the other crucial idea—staging the bomb by separating the primary and secondary—seems to have been exclusively contributed by Ulam. The elegance of the design impressed many scientists, to the point that some who had previously wondered if it was feasible at all suddenly believed that it was inevitable that it would be created by both the USA and USSR. Even Oppenheimer, who was originally opposed to the project, called the idea "technically sweet". The "George" shot of Operation Greenhouse in 1951 tested the basic concept for the first time on a very small scale (and the next shot in the series, "Item", was the first boosted fission weapon), raising expectations to a near certainty that the concept would work.
In November 1, 1952, the Teller-Ulam configuration was tested in the "Ivy Mike" shot at an island in the Enewetak atoll, with a yield of 10.4 megatons (over 450 times more powerful than the bomb dropped on Nagasaki during World War II). The device, dubbed the Sausage, used an extra-large fission bomb as a "trigger" and liquid deuterium—kept in its liquid state by 20 tons of cryogenic equipment—as its fusion fuel, and weighed around 80 tons altogether. Though an initial press blackout was attempted, it was soon announced that the U.S. had detonated a megaton-range hydrogen bomb.
Teller became known in the press as the "father of the hydrogen bomb", a title which he did not seek to discourage. Many of Teller's colleagues were irritated that he seemed to enjoy taking full credit for something he had only a part in, and in response, with encouragement from Enrico Fermi, Teller authored an article titled "The Work of Many People," which appeared in Science magazine in February, 1955, emphasizing that he was not alone in the weapon's development (he would later write in his memoirs that he had told a "white lie" in the 1955 article, and would imply that he should receive full credit for the weapon's invention).[4] Hans Bethe, who also participated in the hydrogen bomb project, once drolly said, "For the sake of history, I think it is more precise to say that Ulam is the father, because he provided the seed, and Teller is the mother, because he remained with the child. As for me, I guess I am the midwife." (Schweber 2000, 166)
The elaborate refrigeration plant necessary to keep its fusion fuel in a liquid state meant that the "Ivy Mike" device was too heavy and too complex to be of practical use. The first deployable Teller-Ulam weapon in the U.S. would not be developed until 1954, when the liquid deuterium fuel of the "Ivy Mike" device would be replaced with a dry fuel of lithium deuteride and tested in the "Castle Bravo" shot (the device was code-named the Shrimp). The dry lithium mixture performed much better than it was expected to, and the "Castle Bravo" device detonated in 1954 had a yield some two and a half times greater than expected (at 15 Mt, it was also the largest weapon ever detonated by the United States). Because much of the yield came from the final fission stage of its uranium tamper, it generated much nuclear fallout, which caused one of the worst nuclear accidents in U.S. history when unforeseen weather patterns blew it over populated areas of the atoll and Japanese fishermen onboard the Daigo Fukuryu Maru.
After an initial period focused on making multi-megaton hydrogen bombs, efforts in the United States shifted towards developing miniaturized Teller-Ulam weapons which could outfit Intercontinental Ballistic Missiles and Submarine Launched Ballistic Missiles. The last major design breakthrough in this respect was accomplished by the mid-1970s, when versions of the Teller-Ulam design were created which could fit on the end of a small MIRVed missile (see the section on the W88 below).
Soviet developments
In the Soviet Union, the scientists working on their own hydrogen bomb project also ran into difficulties in developing a megaton-range fusion weapon. Because Klaus Fuchs had only been at Los Alamos at a very early stage of the hydrogen bomb design (before the Teller-Ulam configuration had been completed), none of his espionage information was of much use, and the Soviet physicists working on the project had to develop their weapon independently.
The first Soviet fusion design, developed by Andrei Sakharov and Vitaly Ginzburg in 1949 (before the Soviets had a working fission bomb), was dubbed the Sloika, after a Russian layer cake, and was not of the Teller-Ulam configuration, but rather used alternating layers of fissile material and lithium deuteride fusion fuel spiked with tritium (this was later dubbed Sakharov's "First Idea"). Though nuclear fusion was technically achieved, it did not have the scaling property of a "staged" weapon, and their first "hydrogen bomb" test, "Joe 4" is not generally considered to be a "true" hydrogen bomb, and is rather considered a hybrid fission/fusion device more similar to a large boosted fission weapon than a Teller-Ulam weapon (though using an order of magnitude more fusion fuel than a boosted weapon). Detonated in 1953 with a yield equivalent to 400 kilotons of TNT (only 15%–20% from fusion), the Sloika device did, however, have the advantage of being a weapon which could actually be delivered to a military target, unlike the "Ivy Mike" device, though it was never widely deployed. Teller had proposed a similar design as early as 1946, dubbed the "Alarm Clock" (meant to "wake up" research into the "Super"), though it was calculated to be ultimately not worth the effort and no prototype was ever developed or tested.
Attempts to use a Sloika design to achieve megaton-range results proved unfeasible in the USSR as it had in the calculations done in the USA (though its value as a publicity tool and even as a practical weapon — some 20 times more powerful than their first fission weapon — should not be underestimated), and the Soviet physicists calculated that at best the design might yield a single megaton of energy if pushed to its limits. After the U.S. tested the "Ivy Mike" device in 1952, proving that a multimegaton bomb could be created, the Soviets searched for an additional design, while continuing to work on improving the Sloika (the "First Idea"). The "Second Idea", as Sakharov referred to it in his memoirs, was a previous proposal by Ginzburg in November 1948 to use lithium deuteride in the bomb, which would, in the course of being bombarded by neutrons, produce tritium. (Holloway 1994, p. 299) In late 1953, physicist Viktor Davidenko achieved the first breakthrough, that of keeping the primary and secondary parts of the bombs in separate pieces ("staging"). The next breakthrough was discovered and developed by Sakharov and Yakov Zeldovich, that of using the X-rays from the fission bomb to compress the secondary before fusion ("radiation implosion"), in the spring of 1954. Sakharov's "Third Idea", as the Teller-Ulam design was known in the USSR, was tested in the shot "RDS-37" in November 1955 with a yield of 1.6 Mt.
If the Russians were able to analyze the fallout data from either the "Ivy Mike" or "Castle Bravo" tests, they would have potentially been able to discern that the fission primary was being kept separate from the fusion secondary, a key part of the Teller-Ulam device, and potentially that the fusion fuel had been subjected to high amounts of compression before detonation. (De Geer 1991) One of the key Soviet bomb designers, Yuli Khariton, later said that:
- At that time, Soviet research was not organized on a sufficiently high level, and useful results were not obtained, although radiochemical analyses of samples of fallout could have provided some useful information about the materials used to produce the explosion. The relationship between certain short-lived isotopes formed in the course of thermonuclear reactions could have made it possible to judge the degree of compression of the thermonuclear fuel, but knowing the degree of compression would not have allowed Soviet scientists to conclude exactly how the exploded device had been made, and it would not have revealed its design. (Khariton and Smirnov 1993)
Sakharov stated in his memoirs that though he and Davidenko had new snow in cardboard boxes several days after the "Mike" test with the hope of analyzing them for information, a chemist at Arzamas-16 (the Soviet weapons laboratory) had mistakenly poured the concentrate down the drain before it could be analyzed. Only in the fall of 1952 did the Soviet Union set up an organized system for monitoring fallout data. (Holloway 1994, p. 314)
The Soviets demonstrated the power of the "staging" concept in October 1961 when they detonated the massive and unwieldy Tsar Bomba, a 50 Mt hydrogen bomb which derived almost 97% of its energy from fusion rather than fission—its uranium tamper was replaced with one of lead shortly before firing, in an effort to prevent excessive nuclear fallout. Had it been fired in its "full" form, it would have yielded at around 100 Mt of TNT. The weapon was technically deployable (it was tested by dropping it from a specially modified bomber), but militarily impractical, and was developed and tested primarily as a show of Soviet strength. It was the largest nuclear weapon developed and tested by any country.
Other countries
The details of the development of the Teller-Ulam design in other countries are less well known. In any event, United Kingdom had initial difficulty in its development of it, failing in its first attempt in May 1957 (its "Grapple I" test failed to ignite as planned, though much of its energy did come from fusion in its secondary), though succeeded in its second attempt in its November 1957 "Grapple X" test (which yielded 1.8 Mt). The British development of the Teller-Ulam design was apparently independent, though they were allowed to share in some U.S. fallout data which may have been useful to them. After their successful detonation of a megaton-range device (and thus their practical understanding of the Teller-Ulam design "secret"), the United States agreed to exchange some of its nuclear designs with Great Britain, leading to the 1958 US-UK Mutual Defence Agreement.
The People's Republic of China detonated its first device using a Teller-Ulam design June 1967 ("Test No. 6"), a mere 32 months after detonating its first fission weapon (the shortest fission-to-fusion development yet known), with a yield of 3.3 Mt. Little is known about the Chinese thermonuclear program, however. Very little is known about the French development of the Teller-Ulam design beyond the fact that they detonated a 2.6 Mt device in the "Canopus" test in August 1968. In 1998, India claimed to detonate a "hydrogen bomb" in its Operation Shakti tests ("Shakti I", specifically), though seismographic readings have lead many non-Indian experts to conclude that this is unlikely, or at least it was unlikely to have been a success as claimed, because of its low yield (claimed to be around 45 kt, though outside experts estimate it at around 30 kt, both extremely low for a successful thermonuclear detonation).[5] However even low-yield tests can have a bearing on thermonuclear capability, as they can provide information on the behavior of primaries without the full ignition of secondaries.[6]
Public knowledge
The Teller-Ulam design was for many years considered one of the top nuclear secrets, and even today it is not discussed in any detail by official publications with origins "behind the fence" of classification. United States Department of Energy (DOE) policy has been, and continues to be, that they do not acknowledge when "leaks" occur, because doing such would acknowledge the accuracy of the supposed leaked information. Aside from images of the warhead casing (but never of the "physics package" itself), most information in the public domain about this design is regulated to a few terse statements by the DOE and the work of a few individual investigators.
Below is a short discussion of the events which lead to the formation of these "public" models of the Teller-Ulam design, with some discussions as to their differences and disagreements with those principles outlined above.
DOE statements
In 1972, the DOE declassified a statement that "The fact that in thermonuclear (TN) weapons, a fission 'primary' is used to trigger a TN reaction in thermonuclear fuel referred to as a 'secondary'", and in 1979 added: "The fact that, in thermonuclear weapons, radiation from a fission explosive can be contained and used to transfer energy to compress and ignite a physically separate component containing thermonuclear fuel." To this latter sentence they specified that "Any elaboration of this statement will be classified." (emphasis in original) The only statement which may pertain to the sparkplug was declassified in 1991, "Fact that fissile and/or fissionable materials are present in some secondaries, material unidentified, location unspecified, use unspecified, and weapons undesignated." In 1998, the DOE declassified the statement that "The fact that materials may be present in channels and the term 'channel filler,' with no elaboration", which may refer to the polystyrene foam (or an analogous substance). (DOE 2001, sect. V.C.)
Whether these statements vindicate some or all of the models presented above is up for interpretation, and official U.S. government releases about the technical details of nuclear weapons have been purposely equivocating in the past (see, i.e., Smyth Report). Other information, such as the types of fuel used in some of the early weapons, has been declassified, though of course precise technical information has not been.
The Progressive case
Most of the current ideas of what the Teller-Ulam design came into public awareness after the DOE attempted to censor a magazine article by U.S. antiweapons activist Howard Morland in 1979 on the "secret of the hydrogen bomb". In 1978, Morland had decided that discovering and exposing this "last remaining secret" would focus attention onto the arms race and allow citizens to feel empowered to question official statements on the importance of nuclear weapons and nuclear secrecy. Most of Morland's ideas about how the weapon worked were compiled from highly accessible sources—the drawings which most inspired his approach came from none other than the Encyclopedia Americana. Morland also interviewed (often informally) many former Los Alamos scientists (including Teller and Ulam, though neither gave him any useful information), and used a variety of interpersonal strategies to encourage informational responses from them (i.e., asking questions such as "Do they still use sparkplugs?" even if he wasn't aware what the latter term specifically referred to). (Morland 1981)
Morland eventually concluded that the "secret" was that the primary and secondary were kept separate and that radiation pressure from the primary compressed the secondary before igniting it. When an early draft of the article, to be published in The Progressive magazine, was sent to the DOE after falling into the hands of a professor who was opposed to Morland's goal, the DOE requested that the article not be published, and pressed for a temporary injunction. After a short court hearing in which the DOE argued that Morland's information was 1. likely derived from classified sources, 2. if not derived from classified sources, itself counted as "secret" information under the "born secret" clause of the 1954 Atomic Energy Act, and 3. was dangerous and would encourage nuclear proliferation. Morland and his lawyers disagreed on all points, but the injunction was granted, as the judge in the case felt that it was safer to grant the injunction and allow Morland, et al., to appeal, which they did in United States v. The Progressive, et al. (1979).
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Through a variety of more complicated circumstances, the DOE case began to wane, as it became clear that some of the data they were attempting to claim as "secret" had been published in a students' encyclopedia a few years earlier. After another H-bomb speculator, Chuck Hansen, had his own ideas about the "secret" (quite different from Morland's) published in a Wisconsin newspaper, the DOE claimed The Progressive case was moot, dropped their suit and allowed the magazine to publish, which it did in November 1979. Morland had by then, however, changed his opinion of how the bomb worked, suggesting that a foam medium (the polystyrene) rather than radiation pressure was used to compress the secondary, and that in the secondary was a sparkplug of fissile material as well. He published these changes, based in part on the proceedings of the appeals trial, as a short errata in The Progressive a month later.[7] In 1981, Morland published a book about his experience, describing in detail the train of thought which led him to his conclusions about the "secret". (Morland 1981; DeVolpi 1981)
Because the DOE sought to censor Morland's work—one of the few times they violated their usual approach of not acknowledging "secret" material which had been released—it is interpreted as being at least partially correct, though to what degree it lacks information or has incorrect information is not known with any great confidence. The difficulty which a number of nations had in developing the Teller-Ulam design (even when they apparently understood the design, such as with the United Kingdom), makes it somewhat unlikely that this simple information alone is what provides the ability to manufacture thermonuclear weapons. Nevertheless, the ideas put forward by Morland in 1979 have been the basis for all current speculation on the Teller-Ulam design.
Variations
There have been a few suggested variations of the Teller-Ulam design which have been suggested by sources claiming to have information from inside of the fence of classification. Whether these are simply different versions of the Teller-Ulam design, or should be understood as contradicting the above descriptions, is up for interpretation.
Richard Rhodes' "Ivy Mike" device in Dark Sun
In his 1995 book, Dark Sun: The Making of the Hydrogen Bomb, author Richard Rhodes describes in detail the internal components of the "Ivy Mike" Sausage device, based on information obtained from extensive interviews with the scientists and engineers who assembled it. According to Rhodes, though there was polystyrene in the "Mike" device, it was not used as a plasma source—the radiation from the primary itself was enough to compress the secondary. Whether or not this would apply only to the "Mike" device, or the Teller-Ulam design in general, is not known, and potentially casts some doubt onto the role of the foam, and to the exact mechanism of radiation "transport". (Rhodes 1995)
W88 revelations
In 1999, a reporter for the San Jose Mercury News reported that the U.S. W88 nuclear warhead, a small MIRVed warhead used on the Trident II SLBM, had an oblate (egg or watermelon shaped) primary (code-named Komodo) and a spherical secondary (code-named Cursa) inside a specially-shaped radiation case (known as the "peanut" for its shape). A story four months later in The New York Times by William Broad reported that in 1995, a supposed double agent from the People's Republic of China delivered information indicating that China knew these details about the W88 warhead as well, supposedly through espionage. (This line of investigation eventually resulted in the abortive trial of Wen Ho Lee.) If these stories are true, it would indicate a variation of the Teller-Ulam design which would allow for the miniaturization required for small MIRVed warheads. (Stober and Hoffman 2001; Morland 2003; Broad 1999)
The value of an oblate primary lies apparently in the fact that a MIRV warhead is limited by the diameter of the primary — if an oblate primary can be made to work properly, then the MIRV warhead can be made considerable smaller yet still deliver a high-yield explosion — a W88 warhead manages to yield up 475 kt with a physics package 68.9 in (1.75 m) long, with a maximum diameter of 21.8 in (0.55 m), and weighing probably less than 800 lb (360 kg).[8] Smaller warheads can allow a nation to fit more of them onto a single missile, as well as improve in more basic flight properties such as speed, mileage, and range.
The calculations for an nonspherical primary are apparently orders of magnitude harder than for a spherical primary, which would likely be of interest to an existing nuclear power like the People's Republic of China (particularly as they no longer conduct nuclear testing, which would yield invaluable design information). (Cox 1999)
References
- Basic principles
- Chuck Hansen, U.S. nuclear weapons: The secret history, (Arlington, TX: Aerofax, 1988). ISBN 0517567407
- Chuck Hansen, The Swords of Armageddon: U.S. nuclear weapons development since 1945, (Sunnyvale, CA: Chukelea Publications, 1995). [9]
- United States Department of Energy, Restricted Data Declassification Decisions, 1946 to the present, Vol. 7 (January 2001).[10]
- History
- Peter Galison and Barton Bernstein, "In any light: Scientists and the decision to build the Superbomb, 1942-1954" Historical Studies in the Physical and Biological Sciences Vol. 19, No. 2 (1989): 267-347.
- David Holloway, Stalin and the bomb: The Soviet Union and atomic energy, 1939-1956 (New Haven, CT: Yale University Press, 1994). ISBN 0300060564
- Richard Rhodes, Dark sun: The making of the hydrogen bomb (New York: Simon and Schuster, 1995). ISBN 068480400X
- S.S. Schweber, In the shadow of the bomb: Bethe, Oppenheimer, and the moral responsibility of the scientist (Princeton, N.J.: Princeton University Press, 2000). ISBN 0691049890
- Gary Stix, "Infamy and honor at the Atomic Café: Edward Teller has no regrets about his contentious career," Scientific American (October 1999): 42-43.
- Analyzing fallout
- Lars-Erik De Geer, "The radioactive signature of the hydrogen bomb" Science and Global Security Vol. 2 (1991): 351-363.[11]
- Yuli Khariton and Yuri Smirnov, "The Khariton version" Bulletin of the Atomic Scientists Vol. 49, No. 4 (May 1993): 20-31.[12]
- The Progressive Case
- Alexander De Volpi, Jerry Marsh, Ted Postol, and George Stanford, Born secret: the H-bomb, the Progressive case and national security (New York: Pergamon Press, 1981). ISBN 0080259952
- Howard Morland, The secret that exploded (New York: Random House, 1981). ISBN 0394512979
- W88 warhead
- William J. Broad, "Spies versus sweat, the debate over China's nuclear advance," New York Times (7 September 1999), p. 1.
- Christopher Cox, chairman, Report of the United States House of Representatives Select Committee on U.S. National Security and Military/Commercial Concerns with the People's Republic of China (1999), esp. Ch. 2, "PRC Theft of U.S. Thermonuclear Warhead Design Information". [13]
- Howard Morland, "The holocaust bomb: A question of time" (February 2003), available online at http://www.fas.org/sgp/eprint/morland.html
- Dan Stober and Ian Hoffman, A convenient spy: Wen Ho Lee and the politics of nuclear espionage (New York: Simon & Schuster, 2001). ISBN 0743223780
External links
- Principles
- "Basic Principles of Staged Radiation Implosion (Teller-Ulam)" from Carey Sublette's NuclearWeaponArchive.org.
- "Hydrogen bomb / Fusion weapons" at GlobalSecurity.org (see also links on right)
- History
- PBS: Race for the Superbomb: Interviews and Transcripts (with U.S. and USSR bomb designers as well as historians).
- Howard Morland on how he discovered the "H-bomb secret" (includes many slides).
- The Progressive November 1979 issue – "The H-Bomb Secret: How we got it, why we're telling" (entire issue online).