Strauss was born and raised in Virginia and, on graduation from high school, intended to study physics at the University of Virginia. But problems with his family’s shoe wholesale business meant that he had to go and work with his father as a salesman. Although after three years he had earned enough to go to college, in 1917 he volunteered to work with Republican politician Herbert Hoover (a future US president) to support the war in Europe. He made important political contacts while working as Hoover’s private secretary and after the war worked to help Jewish refugees from Europe, an experience that gave him a profound dislike of communism. He never made it to college to study physics but instead joined a New York banking firm, becoming a partner in 1929 and making his fortune. A long-time member of the Navy Reserve, he volunteered for active duty in World War II and managed naval munitions, eventually reaching the rank of rear admiral.
Strauss maintained an interest in physics and, following the death of his parents from cancer in the 1930s, set up a fund to support research into radiation treatment of the disease. Through the fund he met prominent physicists of the time, including Leo Szilard. Strauss funded some work by Szilard into fission chain reactions, which would eventually lead to the scientist’s warning to President Roosevelt in 1939 about the possibility of an atomic bomb.
When President Truman formed the AEC in 1947, Strauss was an obvious choice to be one of the first commissioners. As a commissioner, Strauss came into contact with J. Robert Oppenheimer, former scientific leader of the Manhattan Project. Oppenheimer was a totemic figure among many postwar scientists. Not only had he successfully led the scientific effort to design the atomic bombs that hastened the end of the war, but afterwards he had campaigned against a nuclear arms race and argued for the international control of nuclear materials and technology. Oppenheimer was the chair of the AEC’s General Advisory Committee and his liberal views were like a red flag to the conservative Strauss. Strauss was a strong advocate of moving straight on to building an H-bomb, as an ultimate deterrent to Soviet aggression. Oppenheimer, in the 1940s, didn’t think it would work and instead favoured a stockpile of smaller tactical atomic bombs. Strauss was alarmed by the unmasking of Soviet spies linked to the Manhattan Project, including Klaus Fuchs and Julius and Ethel Rosenberg. Oppenheimer was known to have had friends, relatives and colleagues who were communists during the 1930s and many, including Strauss, believed he was an unacceptable security risk. During a congressional hearing at which Strauss lobbied against allowing the export of radioactive isotopes, Oppenheimer mocked him by stating that the isotopes were ‘less important than electronic devices but more important than, let us say, vitamins.’
Once the crash programme to develop the H-bomb was approved by President Truman in 1950 Strauss stepped down from the AEC but he did not forget his animosity towards Oppenheimer. One of Strauss’ first acts when he returned to the AEC as chair in 1953 was to ask the FBI to intensify its surveillance of Oppenheimer, which included following his movements, bugs in his home and office, telephone taps and opening his correspondence. The FBI didn’t find any evidence of disloyalty but Strauss persisted. In December he told Oppenheimer that his security clearance had been revoked and showed him a list of charges against him. Oppenheimer refused to resign and so during the following April and May hearings were held into his security clearance. All of this was taking place during the anti-communist witch-hunts of Senator Joe McCarthy and hearings to investigate such a high-profile figure as Oppenheimer drew huge publicity.
The hearings raked over Oppenheimer’s prewar communist ties and his association with Soviet spies who had worked at Los Alamos. Many prominent scientists, politicians and military officials spoke in his defence. Teller testified, saying that he thought Oppenheimer was loyal to the United States but that his judgment was so questionable that he should be stripped of clearance. Oppenheimer’s own testimony was often inconsistent and erratic and in the end his clearance was revoked. He was widely seen as a victim of anti-communist hysteria; Teller, on account of his testimony, was shunned by the scientific community; and Strauss won a reputation as a McCarthyite witch-hunter.
Back at the AEC, Strauss was unhappy about the slow progress on Project Sherwood. He called a meeting of the project leaders from Princeton, Los Alamos and Livermore plus a few other prominent physicists to discuss the future of the programme. This group of advisers proved to be more cautious than Strauss liked. They described Sherwood as a long-term effort and felt it was too early to speculate about large-scale reactors. They recommended continuing on the same course as before. Strauss had other ideas. He told Johnson to beef up the organisation of Project Sherwood within AEC headquarters and prepare to treble the project’s spending. In addition, despite President Eisenhower’s Atoms for Peace speech in December and a general move towards nuclear declassification, Strauss insisted on tight security.
Johnson appointed one of his staff, Amasa Bishop, to work on managing the project full-time. He also set up a steering committee – made up of the project leaders from each laboratory plus Edward Teller – which met several times a year. With the conferences of Project Sherwood happening at a similar frequency, there was suddenly a sense of urgency among the researchers to get results ready for the next meeting. The numbers working on Sherwood projects grew quickly, from forty-five in March 1954 to 110 a year later and double that by 1956. Strauss lavished money on the project, so much so that researchers almost didn’t know how to spend it all. From the $1 million that Johnson originally secured for 1951-53, the Sherwood budget increased to $1.7 million for 1954 alone, $4.7 million in 1955, $6.7 million in 1956 and $10.7 million in 1957. Strauss even joked about offering a $1 million prize to the first person or group to achieve controlled thermonuclear fusion.
Johnson decided that the stellarator was the most promising of the different approaches and it should be made the focus of Project Sherwood. Model A was showing good confinement and Model B was under construction. This second machine would have a much stronger magnetic field than its predecessor and, Spitzer hoped, would reach ion temperatures of 1 million °C. But in the new regime instituted by Strauss, Spitzer and the other project leaders were starting to feel pressure from the head office. Johnson wanted the Princeton team to start working on additional heating systems for Model B to help it reach higher temperatures. Spitzer, however, was reluctant to do this until they had got Model B running and could see how it performed. Johnson insisted that there was no time to waste. He also wanted the Princeton team to get started on a design for Model C, Spitzer’s putative prototype power reactor.
From Spitzer’s point of view, this was becoming less like a research programme and more like a crash development effort – like the one then going on to develop the H-bomb – where instead of progressing methodically and in sequence, things are done in parallel to save time. But there are dangers in this approach. Moving onto the next thing before Model B is shown to work runs the risk that they may go down the wrong path and have to retrace their steps. Despite Spitzer’s reservations, the Princeton team started work on a design for Model C in the autumn of 1954, a matter of weeks after Model B began operating.
It was the pinch devices that were soon getting the attention, however. A young theorist called Marshall Rosenbluth had arrived at Los Alamos. He had studied for his PhD at the University of Chicago tutored by Edward Teller, who later recruited him to join the H-bomb team. He was not entirely happy about doing bomb work but when he found out what Tuck was doing at Los Alamos he was keen to take part. He and others began working on a more rigorous theoretical model of how a pinched plasma works and came up with M (for motor) theory. This had a dramatic effect. Suddenly the researchers had a better understanding of what the plasma was doing. One of M-theory’s first predictions was that if the plasma current was made stronger, the pinch will heat the plasma to a higher temperature. In a toroidal pinch device like the Perhapsatron, that would require the electromagnet to create a stronger magnetic field, which was
tricky at the time. So Tuck and the Los Alamos researchers began building a straight pinch device in which it would be possible to create a strong current by putting an electrode at each end and a voltage across them. Another team at the University of California, Berkeley, did the same.
By the autumn of 1955, Tuck had a 1m-long pinch device called Columbus along which he could apply 100,000 volts. Much to their surprise, every time the researchers produced a pulse of current to create a pinch they detected millions of neutrons coming out of the plasma. If those neutrons were being produced by thermonuclear reactions, the plasma must be reaching temperatures of millions or tens of millions of °C. There was much excitement throughout the community of Sherwood scientists about the pinch’s success. Tuck, who had kept his goals modest, now started to form grander plans. A power-producing reactor based on a straight pinch would still have to operate in fast pulses, producing a burst of fusion energy before instabilities ripped the plasma apart. He did some rough calculations and estimated that using a large-bore tube an electric pulse equivalent in energy to a ton of TNT would produce several tonnes equivalent of fusion energy.
Not everyone was convinced, however, that the neutrons produced in the straight pinches were from thermonuclear reactions. At a Sherwood conference in October 1955, Stirling Colgate, a researcher from Livermore, pointed out that the pinches were sometimes producing neutrons in conditions which M-theory predicted would create temperatures too low for fusion. Colgate suggested that the pinch teams should try measuring whether the same number of neutrons came out in all directions, as should be the case if the source is a thermonuclear plasma – the same test that ZETA would later be subjected to. The pinch team at Berkeley did the test and found that many more neutrons emerged from one end of the tube than the other. So the neutrons were not thermonuclear: some ions in the plasma were being accelerated to high speed in one direction, producing neutrons by fusion but leaving the bulk of the plasma at too low a temperature. The following spring, when Kurchatov came to Harwell and gave his unexpected lecture about thermonuclear fusion, western scientists learned that their Soviet colleagues had experienced the same surge of hope followed by disappointment when they had detected neutrons from one of their devices in 1952.
This did not kill off US interest in the pinch, however. A couple of ideas for stabilising a pinched plasma had been kicking around for a few years – ideas that Peter Thonemann and his colleagues at Harwell had also incorporated into ZETA. The first was the idea of making the vessel from a conducting metal, or enclosing it in a conducting shell, to repel particles from the walls. The second was the idea of applying a longitudinal magnetic field along the tube to give the plasma a stabilising magnetic ‘backbone.’ Rosenbluth, who would eventually earn himself the nickname ‘the pope of plasma physics,’ incorporated these modifications into his M-theory model of pinches and predicted that, under certain narrow conditions, a pinched plasma could be made stable. By the summer of 1956, Tuck’s team at Los Alamos and the Berkeley group were both showing improved stability using Rosenbluth’s prescription. This opened up exciting possibilities: maybe a pinch didn’t have to be a fast-pulsed device to get some fusion before instability kicked in; maybe it could hold onto its plasma for longer.
Strauss’ effort to get faster results from Project Sherwood seemed to be working, but cracks were starting to appear in the cocoon of secrecy he had wrapped around the project. The Atomic Energy Act of 1954 allowed the US to again share nuclear secrets with allies such as Britain. In line with President Eisenhower’s Atoms for Peace policy, an increasing number of formerly secret nuclear projects were edging out into the light of day. A huge amount was revealed at the first Atoms for Peace conference in Geneva in August 1955 and Homi Bhabha’s prediction about fusion energy put governments under pressure to reveal more. Not wanting to leave the United States looking like it was lagging behind other nations, Strauss was forced to announce the existence of Project Sherwood the next day, but no other details were revealed.
When plans were announced for a follow-up conference in Geneva in 1958, the US administration decided that the AEC should put up a show-stopping exhibit to demonstrate the pre-eminence of American nuclear technology. At first, fusion hadn’t been considered seriously as a candidate for the ‘spectacular,’ but the cost estimates that the AEC commissioners got for displaying other types of reactor proved sky high. Something from Project Sherwood only looked possible because declassification of the programme was starting to seem inevitable. The military justification for maintaining secrecy – that a fusion neutron source could be used to make plutonium for bombs – was evaporating as mining companies found ever larger natural reserves of uranium.
Johnson and Bishop in the AEC’s research division had long been pressing for declassification. In April 1956 they had recommended that fusion information should start to be exchanged with the British and the following month recommended full declassification. Most of the AEC commissioners supported the proposal, but Strauss did not. In September they suggested a slightly watered down proposal: declassify everything apart from any details crucial to a working fusion reactor. To get the most out of the announcement, it should be made just before a major fusion conference to encourage the Soviets to make similar revelations. Strauss still opposed the suggestion, but the commissioners unusually decided to go ahead on a majority vote. By the following month, the first delegation from Harwell arrived to tour the main fusion labs. The US team that visited the UK in November was clearly wowed by ZETA. This was no proof-of-principle lab experiment; ZETA looked like something that could generate power. The size and ambition of the machine was far ahead of any of the American projects and the team members were concerned that, if Britain decided to ship ZETA to Geneva as an exhibit, any Sherwood effort would be overshadowed. Beyond the rivalry between Princeton and Los Alamos, the US teams now had the British and, following Kurchatov’s lecture, the Russians to worry about.
US unease about ZETA increased when it began operating in August 1957 and almost immediately started producing neutrons. Although news of the breakthrough did leak to the press in early September, Strauss was determined to keep a lid on it. He was convinced that the US programme was superior and, although the work on some devices had been slowed by technical problems, both the straight and toroidal pinches were showing promise. The declassification plan suggested that nothing be revealed until the 1958 Geneva conference – a whole year away. If Strauss could induce the British to keep quiet about ZETA until then, Sherwood would have time to catch up and the US exhibit would be the star of Geneva.
But the project leaders at the labs and the AEC commissioners were in two minds about a spectacular fusion exhibit at Geneva. It would bring in extra funding from the government but the months spent preparing the exhibits would distract the scientists from the real business of mastering fusion. And there were still serious doubts that they could achieve thermonuclear neutrons in time. The situation was complicated further by the shock arrival of Sputnik on 5th October. Now Strauss had the added pressure of wanting to make some public demonstration of US technical superiority to trump the Soviet feat. A crisis meeting was called for 19th October to make a decision about Geneva. The project leaders as well as Johnson and Bishop from the AEC had decided in advance that aiming to show a reactor producing thermonuclear neutrons was just too risky and some other lower profile exhibits should be planned. Most of the commissioners didn’t like the odds either. But Strauss was adamant. He wanted fusion to be achieved on his watch, he wanted the US exhibit to overwhelm all others at Geneva, and he wanted to do his bit to restore American pride. So thermonuclear neutrons would be the centrepiece at Geneva. This was a turning point for the US fusion programme: scientists were no longer setting its goals or pace; it had become an instrument of US foreign policy.
While Strauss was able to assert himself over the Geneva exhibit, he was not getting his way over ZETA. The British press had got hold of the fact that the ZETA team wa
s being kept quiet because of US insistence on secrecy and they were painting Strauss as the villain. With newspapers clamouring, the Harwell scientists didn’t know how long they could keep a lid on ZETA. The British wanted to publish their results, and they wanted to do it before Geneva. Strauss finally gave in to the inevitable. To try and lessen the impression that the UK was ahead in the fusion race he resolved to publish details of the US pinch experiments at the same time. But first he sent the team of American researchers to take a look at ZETA to find out if it really was producing thermonuclear neutrons.
The Americans were, by and large, convinced of ZETA’s neutrons. Shortly afterwards the latest versions of the Perhapsatron and the Columbus straight pinch started producing neutrons too. Altogether, things were looking very bright for the pinches. Some had their doubts, however. Spitzer was sceptical that ZETA was really reaching temperatures as high as 5 million °C during such a short pulse. He suspected that a small volume of plasma was being heated more than the rest by an instability. Colgate at Livermore was also concerned about the British temperature claims. He, along with a couple of colleagues, made a careful comparison of all the pinches that were then producing neutrons, including ZETA and Britain’s Sceptre-III at AEI, the Perhapsatron and Columbus. Instead of focusing on the neutrons they looked at the electrical conductivity of the plasma in each case. Using a formula linking conductivity and temperature they concluded that the temperature in ZETA was probably a tenth of Harwell’s claim, so its neutrons could not be thermonuclear.
Nevertheless, Strauss and the US fusion scientists could only grit their teeth in late January when the results from ZETA and the American pinch experiments were published together. As Strauss had feared, the US results were largely ignored and the Harwell scientists were hailed as the conquerors of fusion.
Piece of the Sun : The Quest for Fusion Energy (9781468310412) Page 8