Who invented klystron

Some of these ideas were promising but too complicated; others were discarded as theoretically unsound. Then came June 5, Sig said he remembered the day because that morning he accidentally burned up some fifteen feet of cord and blew the main breaker in the Stanford power house.

On that same day Russell was going back over his notebook. He had recorded some twenty-three possibilities in all. Some overlapped others, so he had narrowed them down to twelve separate ideas, As he explained in a later report,. That day I was occupied in developing a classification of all the schemes we had thought of, so that we could systematically investigate them all and not discover later that we had overlooked some of the most promising.

In the process of developing this classification, I suddenly thought of the velocity grouping principle. From a psychological viewpoint it is interesting that this attempt at classification actually produced the klystron invention. The velocity grouping principle did not fit any of the classification schemes I had contrived and I rather think the idea occurred to me because I was unconsciously attempting to test the validity of my classification.

Hence, I thought up an exception to the classification which actually turned out to be the basic concept of the klystron. The ordinary grid control fails at very high frequency because the electrons don't have time to get an appreciable distance over the space charge barrier during the favourable part of the cycle. The new method is a sort of grid control but none of the electrons are prevented from passing the grid. They are merely slowed down or accelerated Under these conditions the electrons, after passing the control grids, will have variable velocities depending on the phase of the oscillating circuit when the electrons went through.

If the electrons continue in a straight line, the accelerated ones will tend to catch up on the retarded ones and the stream of electrons will be transformed from a uniform beam to one consisting of a series of concentrations or waves of electrons having the same frequency as the exciting frequency. This description of the action of the electrons was followed by a mathematical analysis of the system.

Russell liked to explain this velos;ity grouping or bunching principle in less technical terms by saying:. Just picture a steady stream of cars from San Francisco to Palo Alto; if the cars left San Francisco at equal increments and at the same velocity, then even in Palo Alto they would be evenly spaced and you would call this a direct flow of cars.

But suppose somehow the speed of some cars, as they left San Francisco, was increased a bit and others retarded. Then, with time, the fast cars would tend to catch up with the slow ones and they would bunch into groups. Thus, if the velocity of the cars was sufficiently different or the time long enough, the steady stream of cars would be broken and, under ideal conditions, would arrive in Palo Alto in clearly defined groups.

In the same way an electron tube can be built in which the control of the electron beam is produced by this principle of bunching, rather than by the direct control of the grid of a triode.

Russell told Sig about his latest idea the next morning, spent the day working out the mathematics, and took it to Bill Hansen on June 7th. Bill commented that he realized at once what a wonderful idea it was. He dropped what he was doing and, for the next few days, he, Sig, and Russell discussed how this new way of using the transit time of electrons could be made into an operating device.

Russell's invention had solved the basic transit time problem, but they still had to figure out how to make the idea work in practice. We immediately realized that the idea was so good that all others should be shelved and started to work on the details, of which there were many.

In the first place, an electron beam was needed and many mechanical problems remained to be solved. Most of these were solved by Sig, with much help from Russell and some from myself.

Then there was the design of the resonators, their shape, how to tune them and how to couple them. Here we had a curious difficulty.

For historical reasons, I had fallen into the habit of considering flat ended cylindrical resonators and Rus had acquired the habit from me. An analysis of a tube using such thin cylindrical resonators showed that these were inefficient and the tube would not work.

Everybody felt blue, particularly Sig, who had been itching to get the complete design of the device which Rus and I were so enthusiastic about. Then Bill discovered that one could use re-entrant resonators, and his calculations showed that, for an idealized case, their performance would be much better.

However, the mathematics for re-entrant structures was unfamiliar, and they decided to make some tests. John Woodyard, an electrical engineering graduate student writing his thesis on the verification of Hansen's theory of the rhumbatron, had assembled some test equipment and a model of the rhumbatron consisting of a wooden box about six feet square and two feet high, lined with copper foil.

John's experimental equipment came in handy now. Sig reported, "When Rus and Hansen furnished me with some dimensions, I folded up a reentrant cavity out of copper-lined cardboard. Woodyard's test on his model proved the calculations to be correct, but this cavity looked so much like a spittoon that it took several months to erase the name from the local nomenclature. With the problem of the shape of the resonators solved, work on the design continued. Bill made some final calculations on details of the design, such as determining the size of the coupling loops that would be necessary to feed the energy from the output to the input to cause the tube to oscillate.

Since a cathode design was available, the remaining difficulty was that of finding a suitable mechanical design, which Sig easily solved. It had taken nearly a month for the three men to complete the design and to work out the mathematical problems; now it was Sig's turn. He had been making components for the tube and evaluating the procedures that would be necessary to build it. No tube like it had ever been constructed before, and certain equipment needed for testing just did not exist.

He had to adapt some equipment to meet the exacting requirements and invent and build other pieces himself. Machine parts were made from unfamiliar materials, and he had to devise ways to make microscopic adjustments outside the vacuum to tune the cavities.

He lacked adequate spot welding equipment, and he had no glass blower. The physics department made practically all vacuum systems out of flanged pyrex pipe, bolted together with various fabricated sections. Commented Bill:. Sig finally devised an assembly with a cathode, two resonators one adjustable , an adjustable coupling loop and various gadgetry, all of which could go inside a flanged pyrex pipe, with all leads and adjustments coming out of the metal end-plate.

He made all of this himself, except for the resonators which were spun in San Francisco. As the tube began to take form, Russell and Sig realized there was no way of knowing if or when the tube oscillated.

Russell later described the situation. None of the measuring instruments now available in the microwave region had been developed and the only detectors we had that could be considered for the purpose were the old galena crystal detectors of early radio. We did not even know whether these would function at all at microwave frequencies; if they did function, any meter we could attach to them would be slow acting and the probability was extremely high that we would never detect oscillations.

I finally decided that we could allow a small part of the electron beam used to drive the oscillator to pass through a hole in the last resonator and be deflected into a space beyond by a magnetic field, so that it would land in a moderately small area on a fluorescent screen. This would provide a quick and sensitive detection system, a velocity spectrograph, to help detect any oscillations which occurred.

As it turned out, this invention was probably as important as the klystron itself because, without it, we probably would never have discovered the oscillations, although they would have been present occasionally. The first model we built produced some oscillations which my brother saw on the fluorescent screen but the tuning mechanism was not capable of going through the resonance smoothly and we were unable to repeat the result.

It was about the third model we built which gave reproducible evidence of oscillations. Sig had made his grids with parallel tungsten wires strung across the grid holes in the cavities, but these were not very satisfactory, so be began experimenting with other procedures. He built a hardened drill jig to make grids by drilling holes in copper and then etching the remaining webbing to as fine a section as possible.

He then painstakingly hand-filed the hexagonal grids to the dimensions he wanted. When these were tested, they called for a hamburger celebration,. On August 19, a little over two months after Russell's invention and about a month after the initial design problems were solved, the Model A klystron appeared as a complex mechanical device encased in a vacuum bell jar and oscillated for the first time. Sig reported, "We observed repeatable flashes on our detector screen but everything was unstable and rather disappointing.

Cathode emission died and came back with tuning. Bill Hansen is reported to have said the trouble was probably too much haywire; apparently Sig thought so too:.

About August 21, I took the tube off the pump and replaced the tungsten wire grids with copper hex grids, and installed a micrometer adjustment to the tuning. It was a major operation. On the morning of August 30 I was ready to try again. I threw the switch, tuned the tube a little and there were oscillations spread allover the fluorescent screen. We dug up an old dime store cat's whisker crystal detector and a galvanometer and picked up rf energy all over the room.

We made a quick check on the frequency by moving the crystal detector through the standing waves in the room. In our excitement we figured the wavelength to be 6. Winnie had wired Eric about the initial success of the tube and later wrote Aileen and Wenonah. Evolution of the klystron tube, Stanford University, Model B was designed to be operated under a beII jar.

Its parts were readily accessible, so that improvements could be made and experiments conducted without having to rebuild the tube each time.

I had not written sooner as Sig was about to make another test on that rhumbatron and I wanted to wait and let you know the outcome. Well, yesterday Sig called me in wild excitement to say the thing had oscillated. This, of course, means that victory is practically won and it is just a case of time before they get the other little things worked out Dr.

Webster was so thrilled that he invited the physics department and myself over to his house for beers. The bunching of electrons was Russell's idea so he is very proud of himself and Sig has done such a wonderful job of building the thing and getting it to run that they are both looked upon as heroes around the department.

This morning Dr. Webster called a meeting in order to talk over ways and means of patenting and promoting the tube, so you can see how wonderfully things are working out. If we don't run into patent snags now we ought to have everything well in hand inside of six months or a year.

Such were their hopes and dreams. It was a triumph for Sig, who had pushed to get the project started and worked so hard to complete it.

They learned later that velocity grouping had been discovered earlier and that others were working on the same principle, but all the patent complications were still ahead of them; for the moment their elation was unalloyed.

Edward L. Ginzton described the genesis of the klystron invention as "practically a text book demonstration of the validity of 'management of technology. Usually, when an invention is successful, the natural tendency is for the inventor to minimize the difficulties of developing his idea and to believe he has the world by the tail; the pot of gold at the end of the rainbow is just ahead.

Rarely does it work out so easily. Although the klystron moved from "reduction to practice" in the Stanford physics department to the air war over Britain, and eventually to its broader application in establishing a new technology and a new microwave industry, it was not all smooth sailing.

The "breadboard" tube, called Model A, had proved it could produce microwaves; more models had to be built with better designs and more efficiency, models that eventually could be reproduced and demonstrated as field devices.

Meanwhile, there were some immediate problems. They needed money, patent protection, more people, and more equipment, but first things first. One was a proper name for their tube. Now that it worked, it could no longer be called the" thing," the "can," the" spittoon," or any of the other colorful descriptions that had been given it. Webster decided to consult his friend, Dr.

Frankel, again. After some thought, Dr. Frankel proposed "klystron," which combined the standard syllable "tron," at the time used to denote a vacuum tube, and" klyso," connoting the bunching of waves on a beach.

The name was accepted. As later variations of the klystron acquired such descriptive names as floating drift tube, horse trough, floating kidney, and others, Dr. Webster tried to insist that the flippant researchers use model numbers. When Dr. Webster informed the university administration of their success so that a patent application could be filed, he stressed the need for more money.

Preparation of a patent application began immediately, and the first case was filed October 11, Model A had been successful in demonstrating their theories, but it was just the beginning. A new tube, Model B, was designed as a guinea pig to run' under a bell jar, with parts soft-soldered or screwed together, so they could be removed and redesigned without a new tube being built each time a change was made.

Sig went to work, eventually taking Model A apart to reuse the parts that could be salvaged. Model B, which oscillated about two months later, is now in the Smithsonian Institution. While Sig was working on Model A, Russell and Bill were thinking about other ideas that could utilize the bunching principle. Bill explained, It was plain, from the start, that the bunching principle was more general than its first embodiment in the two-resonator klystron, and we should see what other forms might be useful.

As a result of these possibilities, ripe for the picking, as it were, and two fairly well trained and ingenious people in Russell Varian and myself, ideas began to appear at a prodigious rate. A large number of these, which Bill called system or circuit ideas, related to various things that could be done with the klystron. They decided they could do the same things at microwave frequencies that they had done at lower frequencies, but to do so, they needed to invent rf amplifiers, mixers, AVC mechanisms, detectors, tuning mechanisms, and related equipment.

The ideas that proliferated exceeded their capacity at that time to work on them theoretically, experimentally, or in relation to patents, but in due time these components, as well as the new types of tubes they proposed that summer, were combined into the kind of microwave devices and systems they had envisioned.

One promising variant of the klystron, the monotron, was proposed by Bill Hansen during the summer of ; he hoped it might become a suitable source of power for his X-ray generator.

As they developed it further, it looked as though it would work better under high power requirements than the other types of tubes they had considered, and that it had some important properties of its own that should be protected. Accordingly, the second klystron patent application was filed in November The monotron became, essentially, Bill Hansen's tube.

His work with this tube, step by step, eventually evolved into the Stanford Linear Accelerator, the atom-smashing end result of his long-time interest in extremely high power X-rays. One problem that could not be put off much longer was major financing. Russell and Sig had lived on their savings for more than two years, and their funds were getting low. They first contacted military agencies they thought would be interested but without success.

Then, one day in mid October, Sig decided to go to Oakland to talk to the Bureau of Air Commerce officials to see if they had a good radio man who might understand microwaves and appreciate the possibilities of their tube. The Bureau staff expressed interest but admitted they had no one competent in that field. Disappointed, Sig stopped at the airport on his way home and told his pilot friends about the success of the project.

They understood what such a device could mean to aviation but they had no suggestions about how to get financing. Much to Sig's surprise, he received a telephone call from the Bureau of Air Commerce office the next morning saying that Mr.

Irving A. Metcalfe and Mr. John Easton of their agency had just arrived from the East. Good technical men, they were interested in blind-landing systems and wanted to know more about the tube Sig had mentioned the day before. One of the pilots Sig visited had told them about the developments at Stanford.

A representative of the Sperry Gyroscope Company, Hugh Willis, who was with them, asked if he could see the tube, too. Russell, Sig, Bill, and Dr. Webster held a hurried conference to decide whether they should risk getting involved with a big corporation. Because their need for financing was desperate, they decided to take a chance.

The men arrived at Stanford on October Webster, who acted as spokesman, discovered that they had already developed a design for a blind-landing system but lacked a source of power. He explained how the newly invented klystron could provide the kind of power needed to make such a blind-landing system work.

Model A was demonstrated; the men were impressed and full of questions. After a second visit, each promised to try to interest his respective organization in furthering klystron development.

It was nearly a year and a half before a tube suitable for CAA use was developed sufficiently for field testing. However, the Sperry Gyroscope Company was interested in the klystron as a possible replacement for their searchlights.

A subsequent agreement between Stanford and Russell and Sig provided for approximately the same division of net returns to Stanford as their earlier agreements, but included a small percentage of royalty income for Bill Hansen in recognition of his contribution to the project. This grant could be used to pay salaries, cover the cost of equipment and materials and a limited addition to the staff.

Inevitably the interplay of the values, the priorities, and the philosophies of the highly competitive industrial world of which Russell and Sig were so skeptical with those of the academic world led to controversy and personality conflicts, but the project survived the undercurrents of discontent. In looking back on this period, Bill Hansen commented somewhat bitterly, "Russel Varian's time was almost entirely taken up by patents while Webster and I had our university duties to attend to.

During this time we were business men, amateur lawyers and patent attorneys. To these busy scientists, such matters took up too much of their precious research time.

Meanwhile, for the present at least, some of their immediate problems were solved. The employed a couple of machinists and ordered some good precision equipment, including such needed items as a spot welder, a Monarch lathe, a Litton glass lathe, and a Van Norman milling machine, which Bill had long coveted.

John Woodyard was put on half-time salary until he completed his Ph. In March a second man was employed, Edward L. Ginzton , who also was a graduate student in electrical engineering working on his dissertation. These two men, plus the machinists and some part-time summer help, constituted the klystron staff, and they were responsible for much of the subsequent development work. At best, the relationship between Russell, Sig, and Bill Hansen and Hugh Willis, the Sperry engineer assigned as liaison between Stanford and Sperry, was an uneasy truce, with Willis representing all that the Stanford researchers most resented in industrial control, whether deserved or not.

The following incidents, some significant, some minor, are typical. The question of academic freedom was first to surface. When the Stanford-Sperry agreement was being negotiated, Hugh Willis wanted to be sure that the project would have the continued services of both Dr. Webster and Bill Hansen, whom he considered the important members of the klystron team.

The issue reached the explosive stage when first Dr. Although he was opposed to this requirement as a matter of principle, Dr. Webster took the position that, as head of the department, he should do whatever was most advantageous to the university.

Bill Hansen flatly refused, declaring that it was his right to spend his personal research time as he pleased. Sperry refused to compromise. The university officials were eager to proceed with the all-important funding but they could not require that a member of the faculty relinquish his right to his free research time. After acrimonious argument, Bill finally gave in, when it was agreed that a limited amount of work on the rhumbatron and monotron would be considered allowable research, "just to keep me happy," he said later.

He signed the agreement, then went home to Fresno in high dudgeon "to take a much needed vacation" for a month or six weeks, which he spent in writing papers and designing an antenna.

Webster tried to patch up the quarrel in a letter written May 30, , in which he urged Bill to return because Sig was ill and they needed him to help complete the sending and receiving tests Sig had planned.

Webster wrote, "on this business of how much you need a vacation or anything of that sort, you probably know better than I. Above all else, we must be sure that whatever is said about the loss of academic freedom or our becoming a little G-E Lab, we do not want to have this industrialization go so far as the introduction of time clocks! Please note that the main point of this is to acquaint you with the status of the project and the special need of your contribution.

The next conflict arose in the fall of Sig was ill and Russell immersed in patent work, which left Bill Hansen the key figure in the klystron research; in addition, he had his teaching responsibilities. His staff consisted of John Woodyard, presumably working half time, and the part-time help of a couple of department mechanics. He needed more help and made several requests for permission to hire research and technical men who could fill in for Russell and Sig.

Instead, Hugh Willis had three engineers transferred from Sperry, whose eventual role would be to set up a preproduction facility for manufacturing the klystron.

They were reasonably competent engineers, but geared to manufacturing rather than research and took their orders from Willis, rather than from Webster or Hansen. They did not solve Bill's need for skilled research personnel, although they did help somewhat on routine work and learned what a klystron was all about.

They also caused considerable friction, especially with Dr. Webster, when they ignored the long-standing physics department "no smoking" rule, in spite of Webster's stern warnings. They also needed desk space and working room for the mechanics they hired, and space was at a premium. The new equipment Sperry had supplied had already taken up space previously allocated to Bill Hansen's rhumbatron and Dr. Bloch's research. In desperation, Dr. Webster had obtained permission to roof over the light well as the only way he could expand space, and he had moved the rhumbatron and Bloch's apparatus into that limited area.

The three desks were squeezed in, but that did not satisfy the Sperry engineers. They demanded that Dr. Webster turn over to them half of the entire physics department, including laboratory, shop, and office space, so they could initiate a manufacturing program. That was too much for Dr.

Webster, who informed them in no uncertain terms that they could go elsewhere if they weren't satisfied, and the rift widened. Webster went east for the Christmas holidays, he took up the matter with the Sperry management, and a policy decision was made that Sperry would operate a separate facility of their own for this production work. It took several months to locate and equip such a building, which was in San Carlos, and when they made the move, the three engineers and the mechanics they had employed were transferred to the new location.

This helped relieve the friction, but Bill Hansen was still without the research personnel he needed. There were more problems, this time over Russell and Sig's continued participation in the project.

When Sig first became ill with another attack of tuberculosis, it was hoped that he would be laid up for only a few months, but he was in bed for most of a year. Sig was paid from Sperry funds but there was no provision for sick pay, and Sperry at first refused to continue him on the payroll. However, the Sperry-Stanford agreement had specified that Russell and Sig would be paid either as Stanford employees out of Sperry funds or from an advance on royalties.

Stanford elected to continue Sig's salary on the latter basis, if necessary, and Sperry capitulated. Some six months later, when the budget was being considered, the Stanford comptroller called Dr.

Webster in to discuss some matters that he said had come up recently. They had no wish to disturb the Stanford patent picture, however. They also stated that they considered Sig a talented mechanic, but one who was replaceable, as his current illness indicated. Russell, they said, would be of no value to their organization once his work on patents was completed. They had requested Stanford to dismiss Sig from the project as soon as possible and Russell when he completed his current patent work.

Webster said he promptly told the comptroller that he would personally guarantee that he, Bill Hansen, Russell, and Sig would pull out of the project if Sperry tried to put over anything like that. The comptroller tried to calm him down, explaining he made the suggestions at Sperry's request to see what Webster thought about them, but that Stanford had no intention of abrogating its agreement with Russell and Sig.

Officially, nothing more was heard of the plan, and Dr. Webster said he decided not to tell Bill or the Varians about the conversation. However, rumor persisted, and in July a very worried Sig wrote Russell, then in the East, that he heard on good authority that Sperry planned to dump him as soon as possible, as well as Russell, when he completed his patent work.

Russell discussed the matter with Dr. Bassett, in charge of the klystron project at Sperry, and was assured there was no truth to the rumor; they hoped Russell and Sig would continue their work on the klystron just as long as they wished to do so.

Nothing more was heard about this proposed ouster, but it was felt that Sig's subsequent relapse may have resulted from his pushing himself to prove he was still a viable member of the project. Budgets were another irritant. They were rarely discussed with either Dr.

Webster or Bill Hansen, who would get information second-hand through the manager of the San Carlos facility. In addition to this lack of courtesy, they felt their needs were not given consideration nor their recommendations on research heeded. Furthermore, papers to be presented at scientific meetings or for publication had to be submitted for approval and, on occasion, were ordered withdrawn without explanation or with the comment that the mean on the West Coast were apparently notas aware as they were in the East of the seriousness of the war in Europe.

In the opinion of the Stanford men, most of the secrecy imposed was for industrial, not defense, reasons. When it came to preparing the definitive article on the klystron, Bill Hansen, who had had numerous papers published, offered to write the article with assistance from Russell.

It was returned a couple of times because Hugh Willis did not like Bill's style, he said, and did not think that some of the data Russell and Bill felt most important needed to be included.

Instead of returning it a third time, he wrote he had asked Dr. Webster, who was then in the East, to rewrite it, to which Bill Hansen replied he could let Dr. Webster do whatever he wanted to with it; when you had to get the approval of two Varians, one Hansen, two patent attorneys, one MIT physicist Dr.

Bowles , and the whole Sperry hierarchy for any change in a word or phrase, the article wasn't worth any more of his time or effort. Webster's draft eventually appeared over Russell and Sig's names. However, in spite of their resentment at these and other incidents, they were all aware of the importance of the work they were doing, and, while they grumbled, they made the best of the restrictions Sperry imposed.

Patents were an urgent matter. Bill had little patience or interest in such matters, so Russell took it upon himself to handle them. He had kept the records and had acquired considerable information about patent law through his earlier contacts with Don Lippencott and while he was working for Farnsworth. He also knew it would be necessary to work closely with patent attorneys who were unfamiliar with this new field of microwave physics. He had no illusions about what was ahead of him.

He prepared the preliminary material for the klystron and monotron patent applications and began writing up applications for their numerous other ideas, getting them filed or ready for filing.

It was slow, tedious work, but Russell was patient and disciplined, thinking through all aspects of each case and making sure nothing was overlooked or misstated. He knew the importance of broad patent claims that left no loopholes where competing claims on portions of their inventions might be allowed later.

Although he would have preferred to continue with research, he felt it his obligation to protect their patents in any way he could. In his painstaking scrutiny of every claim, Russell's accurate memory served him well. He had recognized early in his patent activity the need to check and double-check the work of patent attorneys, especially on minute or unique aspects of their cases, to be certain that they fully understood the significance of claims that Russell felt a skilled inventor might try to challenge.

When Sperry became involved in the klystron project, they requested a statement of the patent position. Russell noted that, as of January 21, , 45 of their ideas were included in patent applications that had been filed or were being processed for filing; there were 45 other ideas he had not had time to cover; 8 were of doubtful value; only 3 did not work.

Their ideas had been prolific and their errors few during those eight months since Russell began his notebook entries on the klystron-entries that included not only his ideas but also those of Bill Hansen and others. This was only the beginning of his involvement with patents. During the next two years he had time for little else. Both Russell and Bill knew that others might have preceded them without their knowledge, and this possibility had spurred their efforts to investigate microwave components at the very beginning of the project.

As investigation of the patent situation expanded, they learned that the bunching principle had been discovered by Assenjeva and Oscar Heil in , but that the Heils had not combined their theory with any kind of resonator.

They also learned that work at General Electric, based on the same principle but developed separately, might have come close to predating the successful oscillation of Sig's Model A.

Inventions by Sloan, Llewellyn, Hahn, and Potter presented possible conflicting claims with both the rhumbatron and klystron patent applications, and there could have been others as well. Their patent position was not too strong, they discovered, and in the final determination of their claims, much depended on Russell's having combined the bunching principle with the rhumbatron resonator to produce a new microwave tube.

Said Bill, "It is interesting to note that, of the groups having the bunching principle, we are the only ones who seem to have really accomplished much, and this is entirely due to our use of good resonators. This is rather galling as the resonators seem impossible to protect. On this basis, they were eventually awarded their patents. Sig was left pretty much on his own in the physics laboratory after the success of Model A.

Bill Hansen had to resume his teaching schedule as the fall quarter began, and Russell was immersed in writing patent applications. As the three considered their research project, they agreed that the next step would be to build tubes that could receive and transmit signals.

Although the experiment did not work, it did indicate the kind of improvements that would be necessary in their next models. They then decided to see if two identical cm. With a design in hand, and the help of John Woodyard and a machinist,. Sig began work on models C1 and C2.

As usual, he drove himself to get them completed as quickly as possible. In about four months he and Dr. Webster were ready to begin experiments in sending and receiving when, on May 4, by way of a birthday present, he said, he came down with another attack of tuberculosis. He spent the better part of the next two years in bed or working only a few hours a day.

Sig's illness occurred just about a year after he and Russell began work at Stanford. Surprisingly, during that year they had accomplished much of what they had set out to do. They had produced a microwave tube that, in due time, would provide the blind-landing instrumentation Sig had hoped for and, more importantly, could be used to detect enemy airplanes.

He was on a salary, though a much smaller one than he had earned as a pilot, but with the promise of royalty income in the future. Financial backing was available to assure further development. Producing a fully instrumented device was far from completed but there were others who could continue the work Sig had pioneered so successfully. He paid a high price for what he had accomplished and, for the time being, his participation was limited.

As he recovered, however, he became as productive as he had been before. It was ironic, but not surprising, that it was Sig who became ill and had to watch from the sidelines as others completed the work he had started. Russell functioned at his own pace, always thinking about a project on which he was working but usually under much less pressure than Sig did.

His ideas came to him at unexpected times and places. Sig tended to criticize Russell for being too slow, for not working as many hours in the laboratory as Sig thought he should. Russell was not much of a mechanic, but he did understand the electronics end of the work and willingly lent a hand when he could, although he knew his lack of skill often frustrated Sig, who paid no attention to time, meals, or his own weariness when he had something that he wanted to finish or that stymied him.

He was a worrier, forcing himself to complete whatever he was working on as quickly as possible, to be sure nothing went wrong. Although Sig's active participation was sorely missed, the klystron project continued. The "crew" usually met at his house during the evenings to go over what had been accomplished during the day, to discuss experiments, or to propose new procedures.

Sig kept in close touch with the work at Stanford and, later, at San Carlos, where Sperry established a facility to handle preproduction engineering as the tubes moved from the research stage to pilot production. Bill Hansen and John Woodyard completed the tests on Sig's C1 and C2 transmitter and receiver set-up, which was promptly nicknamed the Boomatron, and demonstrated that Russell's concept of a radar system using such tubes would work. Theoretical studies and experiments on these tubes continued over the next few months, and when Ed Ginzton joined the staff the next spring, he went to work on developing a new improved Model F series of transmitting and receiving tubes.

Meanwhile, because the CAA was still asking for a klystron to test in their blind-landing system, it was decided to build a tube planned specifically for that purpose. Bill and Russell designed a cm. When completed near the end of , the tube worked well under laboratory conditions, but they were all somewhat apprehensive when it was finally shipped to the Massachusetts Institute of Technology MIT in January , in the custody of John Woodyard.

Their tube, the first to be demonstrated away from "home," was to be tested in the "straight line" blind-landing system designed by Dr. Bowles of MIT and Dr. Irving Metcalfe of the CAA. The cm. It was the first working klystron that physicists and engineers there had been able to observe. Because of security restrictions, which had been imposed by Sperry for industrial reasons and by the National Defense Research Council, little was known about this new microwave tube.

Afterward the technology had a great influence of the work of UK and US researchers studying radar devices. Here, it is important to mention a physicist named W. Hansen whose work was instrumental in the advancement of klystron technology; the Varian brothers mentioned him in a paper published by them in The concept of resonator analysis by Hansen showed that the process of accelerating electrons towards a target could also be used to decelerate them.

This was all about transferring the kinetic energy of electrons to RF energy in a resonator. During World War II, the Axis powers were mostly dependent on low-powered klystron technology for their radar system-based microwave generation.

In contrast, the Allies made use of the powerful cavity magnetron technology for the same purpose of microwave generation; but this was a frequency drifting technology. Later, there were advancements in the klystron tube technology for high power applications like radar systems and synchrotrons. After the Second World War, the Varian brothers went on with their research in the field of microwave and radar energy; they researched to find a cure for cancer. They established Varian Systems for their medical field research.

This company is using the same klystron tube technology to date to in their cancer research. The main purpose of a klystron tube is to generate microwave energy and act as a sensitive amplifier.