Internment

Once in London, Kompfner pursued his love of physics⁴ by visiting the Patent Office library in the evenings and reading publications. In 1935 he started to keep notebooks in which he recorded his ideas and two years later he received his first patent for a television pickup device. He tried to market it, but without success. Also in 1935, another love of his life developed when he met Peggy Mason at the Westminster swimming club; Kompfner was a keen swimmer. They married on the 29th April, 1939 and subsequently had two children, a boy and a girl.

One day in June, 1940, Peggy returned home from work to find that her husband had been taken to Brixton police station and interned as an enemy alien⁵. His internment was spent on the Isle of Man where he shared quarters with Wolfgang Fuchs, the mathematician. Apparently, they talked about physics.

Kompfner's internment was thankfully short. Before he was detained he had sent a paper on magnetrons to the magazine Wireless Engineer, the editor of which had brought the paper to the attention of the Admiralty. Kompfner had meanwhile declared himself to be stateless⁶ and friends were petitioning for his freedom. He was duly released in December, 1940, after six months. Then, "I was more or less drafted to the physics department of the University of Birmingham," Kompfner wrote in 1964. It was there, under the guidance of Professor Mark Oliphant, that the Admiralty had set up a secret research group with the task of making a practical centimetre radar system. Kompfner arrived in 1941 and within two years had invented the travelling-wave tube.

Travelling-wave Tube

At Birmingham, Kompfner was assigned to work with researchers P.B. Moon and R.R. Nimmo. "I owe a lot to them," he wrote. They taught him physics and electronics, how to experiment and how to set up theoretical models. He learned well.

His task was to further develop the klystron amplifier and improve its noise figure. He followed the received wisdom of how to do this and "spent two years building klystrons along these lines and getting very discouraged with it in the process". "There is nothing like a goodly amount of dissatisfaction and unhappiness to bring on invention," he has remarked.

Outside work, he began to follow a quite different idea to that of the klystron: he would move the field with the electrons. His notebook for the 6th September 1940 records the idea of making the field move at the same velocity as the electrons. He needed to reduce this velocity and, after discussions with colleagues, the idea of using a helix as a transmission line was born. Kompfner then went to see the acknowledged expert on transmission lines at Birmingham. The expert thought it a poor idea but, when Kompfner tried it, he found that it did work. "I was tactful enough not to go back and tell the expert, but I did not consult him again," said Kompfner. "I might remark that there is no harm in getting expert advice. But don't take it."

The story of the invention of the travelling-wave tube is too complex to describe fully here, and Kompfner himself has given a detailed account elsewhere. Ideas changed, blind alleys⁷ were followed (six months were wasted down one), the helix was abandoned and then returned to and colleagues pointed out mistakes in his theories.

In August, 1943, the group at Birmingham broke up and half the staff were moved to Los Alamos to work on the atom bomb. With others, Kompfner decided to stay in England where he would now be allowed to work officially on his, now well known, homework. Despite setbacks, progress was made. Then in 1944 the group at Birmingham was dispersed and he was moved to the Clarendon Laboratory at Oxford University.

At Oxford, he was visited by Dr John Pierce from Bell Laboratories who had read some of the secret wartime memoranda which described his work. (Incidentally, the first British publication describing the TWT appeared in Wireless World in 1946.) Back in America, Pierce was able to develop the theory of the tube, but it was Kompfner who, virtually single handedly¹, conceived the idea and built working travelling-wave tubes. They were the first of a family of devices which came to be used in radar and space communications.

After the war ended, Kompfner became a British subject⁹ (1947) and in 1951 he received a D.Phil ¹⁰, in physics from Oxford. Meanwhile, Pierce had persuaded him to move to Bell Laboratories in the USA. After a long wait for a visa he joined Bell on the 27th December 1951 and continued his research on microwave tubes. In 1955 he became Director of Electronics Research.. By 1962 he was Associate Executive Director of Research and Communication Sciences Division and his influence was felt on research programmes as varied as masers, lasers, superconducting magnets and optical communications. Also, he had taken out American citizenship.