1929

Henderson and the APL


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Joseph Edmonds Henderson: It's hard to know where to begin to describe this prolific and controversial figure who helped build up the UW physics department during the 1930s and 40s and founded the UW's Applied Physics Laboratory (APL) in 1943.

The image of Henderson is that of a hard-driving wheeler-dealer with a stubborn streak who ran things the way he wanted, a man of relentless energy who inspired loyalty among his students and staff. His legacy is a formidable list of achievements. Over the years that he served in the physics department, he supervised the first physics Ph.D. student, built two generations of particle accelerators, launched programs in nuclear physics and cosmic ray research, supported the development of low-temperature physics, and founded the APL, which achieved many successes for the Navy.

Classified work funded by the military at APL ultimately led to a rift between physics faculty and Henderson, resulting in APL splitting off from the department during the 1950s and striking out on its own course as a separate entity on campus. APL today has become a leader in underwater and ocean exploration technologies.

Henderson was recruited in 1929 to join the UW physics department from Yale, where he was doing post-doctoral research on "soft" x-rays (x-rays of relatively low energy). He arrived on campus to find a brand new physics building, but with little equipment in it; and shortly thereafter, the onset of the Depression made building up a program even more difficult. Somehow, Henderson and colleagues were able to launch new projects.

Swedish Hospital helped out by making available its new, million-volt x-ray machine. Doctors used the device by day to treat cancer; UW physicists used it by night to conduct research. Equipped with two special tubes built by UW researchers, the device could accelerate negatively-charged electrons as well as positive ions. The first artificial nuclear disintegration achieved in the Pacific Northwest was accomplished with the apparatus in 1933. Other studies by UW physicists at Swedish on Cerenkov radiation led to some of the first American scientific papers on this phenomenon. Cerenkov radiation, discovered in the 1930s by Soviet scientist Pavel Cerenkov, can be observed as the eerie blue glow in water tanks holding spent nuclear reactor fuel. It is produced by the deceleration of electrons as they pass through the water.

[Applied Physics Laboratory newsletter]
Front page of Applied Physics Laboratory newsletter describing wartime work on the Mark 9 Exploder, January 1945

A new type of particle accelerator called the betatron was designed by Henderson and colleagues in the late 1930s. Named after the beta particles it accelerated, the device was later adapted by researchers in Illinois into what we know today as the synchrotron.

Henderson was particularly interested in the phenomenon of field emission: emission of electrons from metals subjected to an electric field. His fundamental research led to practical applications such as high-voltage, high-current x-ray tubes. With financial backing from Howard W. Vollum and Jack Murdock--founders of what would become the well-known high-tech firm, Tektronix--Henderson and colleagues established the Field Emission Corporation to market their technology. The venture came to a tragic end when Murdock met an untimely death in 1971; Field Emission Corporation was later purchased by Hewlett-Packard. The field-emission technology ultimately led to a technique to burn circuits onto silicon computer chips, allowing the chips to be miniaturized to an unprecedented degree.

During World War II, Henderson went to the U.S. Bureau of Standards, where he worked on an improved fuse for the military's weapons. When he returned to the University in 1943, he established the APL to respond to a Navy request for a more reliable exploder for torpedoes. The goal was to create a device that would cause the torpedo to detonate only when it was under the keel of the target ship where it would be most effective. APL's Mark 9 Torpedo Exploder, developed in 1945, was a significant improvement over earlier devices, which were ineffectual or unreliable. Later modifications of the device are still in use today.

APL continued in the years after the war to do contract research for the Navy--notably, to develop underwater tracking ranges used by the Navy for the testing and evaluation of torpedoes, for the alignment of sensor systems, and for tracking ships during exercises. The ability to track underwater objects accurately and reliably has helped to improve the performance of Navy weapon systems.

A 1959 article in The Seattle Times notes:

Origination of the concept which makes the 3-D range possible is typical of many great scientific discoveries. That is, research in one line often leads to unthought of applications.

In this case, the Applied Physics Laboratory people were conducting a study of the properties of sea water when the principles were discovered which make it possible for the position of a torpedo (or submarine) to be tracked continuously and accurately.footnote 1

Most of these ranges are still in operation. The Lab also designed underwater equipment to measure the blasts from the nuclear weapons test at Bikini Atoll.

In later years, APL began to receive Navy support for research of a more academic and basic nature that made possible such projects as building the UW's 60-inch cyclotron and investigating cosmic rays.footnote 2 Soon though, the members of the physics faculty became more and more concerned about military funding of academic research. Faculty were uncomfortable with the growing role of APL in supporting--and perhaps even controlling--graduate research in the department. The ties to the physics department were severed in 1952, and the APL reorganized as a separate entity run by Henderson.

Eventually, after Henderson retired, the APL was reorganized as part of the College of Ocean and Fishery Sciences. The Lab grew closer to the academic side of the university, and more of its activities were directed toward non-classified projects.

Much has been accomplished since those early days when Henderson arrived at the UW. In a 1987 article about Henderson in the Seattle Weekly, Keith Ervin concludes:

With considerable help from Henderson and those who have followed him, the University of Washington's physics department has grown into an internationally respected school. Henderson introduced particle physics at the university. His associate Paul Higgs developed capabilities in low-temperature phenomena. Seth Neddermeyer, discoverer of two subatomic particles, studied cosmic rays in the UW cloud chamberIt has taken decades of bootstrapping by committed faculty members to build a high-quality physics department. Much has been accomplished since the 1920s, when university administrators and legislators first decided to build up the department.footnote 3

"APL has had a distinguished history of applying science and technology to national needs," notes APL Director Robert C. Spindel. "In the early days it was World War II, and after that, the Cold War. While today we still emphasize Navy applications, we are also now focused on other pressing national issues such as our environment, our economy, and our health, which require the same kind of innovation and creativity that we have successfully demonstrated in the past," he explains.

APL Deputy Director John Harlett elaborates: "Currently, nearly two thirds of the program is fundamental research, involving some 30 to 40 graduate students. Individual principal investigators submit proposals to funding agencies, just like any other department on campus," he notes. "The other third of our work is more applied, but very little of that is classified. APL in Henderson's day was a secure building, complete with uniformed guards. Henderson Hall today is an open building, much like any other on campus. Although the Navy is still our primary sponsor, almost a third of our funding is from non-Department of Defense agencies." For example, a major new program in ultrasound has resulted in new ties with faculty in bioengineering and medicine on campus.

Today, the Lab is recognized as a world leader in research on underwater sound propagation. Work at APL has yielded major advances in understanding of the physics of sound interacting with the ocean floor. This information is applied in the development of models which predict the performance of sonar technologies. Furthermore, the Lab's Acoustics and Electromagnetics Department is exploring how long-distance underwater acoustic transmissions can be used to monitor average ocean temperature, an important indicator of global warming.

The lab is also an international leader in studies of air-sea-ice interaction in the polar oceans. The lab's Polar Science Center, initiated during the mid-1970s, continues to study ice characteristics and dynamics through a system of drifting buoys and satellite remote sensing. The work has yielded new knowledge about the role of the Arctic in global climate change.

In 1993, the first-ever civilian use of a Navy nuclear submarine took half a dozen scientists, including two from the UW's APLto conduct research under the Arctic ice cap. The mobility of the submarine allowed scientists to make measurements without being inhibited by ice conditions. Researchers measured the mass of the ice using the submarine's sonar as the vessel cruised beneath the polar cap, gathering data that will help track global climate change. The cruise has led to a major change in Arctic scientists' understanding of ocean circulation. It was followed up in 1995 with a second submarine voyage, once again with the participation of APL scientists.


  1. "Strange 'Fish' Run in Dabob: Navy uses 'miniature ocean,' arm of Hood Canal, for tests of torpedoes and submarines," The Seattle Times, February 15, 1959, p. 4.
  2. "Cosmic Ray Tracks Studies at Lofty Field Site," The Trend in Engineering, 3 (3), July, 1951.
  3. "Fiscal Physics," Keith Ervin, the Weekly, May 6-12, 1987.

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