Albert Wallace Hull (19 April 1880 – 22 January 1966) was an American physicist and electrical engineer who made contributions to the development of

vacuum tube A vacuum tube, electron tube, thermionic valve (British usage), or tube (North America) is a device that controls electric current flow in a high vacuum between electrodes to which an electric voltage, potential difference has been applied. It ...

s, and invented the

magnetron The cavity magnetron is a high-power vacuum tube used in early radar systems and subsequently in microwave oven, microwave ovens and in linear particle accelerators. A cavity magnetron generates microwaves using the interaction of a stream of ...

. He was a member of the

National Academy of Sciences The National Academy of Sciences (NAS) is a United States nonprofit, NGO, non-governmental organization. NAS is part of the National Academies of Sciences, Engineering, and Medicine, along with the National Academy of Engineering (NAE) and the ...

Biography

Ballistic Research Lab Advisory Committee First Meeting

He was born on 19 April 1880 in Southington, Connecticut. He majored in Greek and after taking one undergraduate course in

physics Physics is the scientific study of matter, its Elementary particle, fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge whi ...

, graduated from

Yale University Yale University is a Private university, private Ivy League research university in New Haven, Connecticut, United States. Founded in 1701, Yale is the List of Colonial Colleges, third-oldest institution of higher education in the United Stat ...

. He taught languages at The Albany Academy before returning to Yale, to take a doctorate in

. He then undertook research on photoelectricity whilst teaching physics for five years at the Worcester Polytechnic Institute. In 1914 Hull joined the

General Electric General Electric Company (GE) was an American Multinational corporation, multinational Conglomerate (company), conglomerate founded in 1892, incorporated in the New York (state), state of New York and headquartered in Boston. Over the year ...

Research Laboratory (GERL) in

Schenectady, New York Schenectady ( ) is a City (New York), city in Schenectady County, New York, United States, of which it is the county seat. As of the United States Census 2020, 2020 census, the city's population of 67,047 made it the state's ninth-most populo ...

and remained there until his retirement in 1949. During 1916, Hull began investigation into the use of magnetic control of thermionic valves (vacuum tubes) as an alternative to grid or electrostatic control and he had tested successfully magnetic control by applying a magnetic field parallel to the axis of the tube. Initially, Hull's work on these novel electron tubes was part of an effort at General Electric to develop amplifiers and oscillators that might be used to circumvent the vacuum- tube triode patents of Lee de Forest and Edwin Armstrong. Hull was promoted to assistant director of the GERL in 1928. He served as president of the

American Physical Society The American Physical Society (APS) is a not-for-profit membership organization of professionals in physics and related disciplines, comprising nearly fifty divisions, sections, and other units. Its mission is the advancement and diffusion of ...

in 1942. He retired from General Electric Research Laboratory (GERL) in 1949. He did consulting work and served on an advisory committee of the Army Ballistic Research Laboratory after retirement from General Electric. He died on 22 January 1966 at the age of 85 in

Dynatron

He invented the dynatron vacuum tube which had three electrodes: a thermionic cathode, a perforated anode, and a supplementary anode or plate. In normal operation the supplementary anode was maintained at a lower positive voltage than the perforated anode. The

secondary emission In particle physics, secondary emission is a phenomenon where primary incident particles of sufficient energy, when hitting a surface or passing through some material, induce the emission of secondary particles. The term often refers to the emi ...

of electrons from the plate made the dynatron behave as a true negative resistance and so the tube could generate oscillations over a wide range of frequencies or be used as an amplifier. When a control grid was added between the cathode and the perforated anode, the device was called a "pliodynatron."

Magnetron

By 1920 his research led to his invention of the

. This took the form of a central cathode and a coaxial cylindrical anode split into two halves, with an axial magnetic field produced by an external coil. The Hull magnetron was tested as an amplifier in radio receivers and also as a low-frequency oscillator. It was reported in 1925 that a magnetron made at GERL could generate a power of 15 kW at a frequency of 20 kHz. At the time Hull anticipated that the magnetron would find greater use as a power converter than in communication applications. Hull's split-anode magnetron didn't prove to be capable of high frequency or high power output and was little used. During WWII John Randall and Harry Boot built on Hull's concept to develop the modern cavity magnetron, the first device which could produce high power at microwave frequencies, and the resulting centimeter-band

radar Radar is a system that uses radio waves to determine the distance ('' ranging''), direction ( azimuth and elevation angles), and radial velocity of objects relative to the site. It is a radiodetermination method used to detect and track ...

proved a crucial advantage for the Allies in aerial warfare.

Gas-filled electron tubes

During the 1920s, Hull also was a major contributor to the development of gas-filled electron tubes at the GERL. He discovered how to protect thermionic cathodes from rapid disintegration under ion bombardment. This discovery enabled the successful development of hot-cathode thyratrons (gaseous triodes) and phanotrons (gaseous diodes).

Publications

In the 1918 issue of the

Proceedings of the IRE The ''Proceedings of the IEEE'' is a monthly peer-reviewed scientific journal published by the Institute of Electrical and Electronics Engineers (IEEE). The journal focuses on electrical engineering and computer science. According to the ''Journa ...

he published a paper on the dynatron vacuum tube which he had invented. During his career in electronics he was the author or coauthor of 72 technical publications and was awarded 94 patents.

Awards

*1924 Howard N. Potts Medal of the Franklin Institute. *1930

IEEE Morris N. Liebmann Memorial Award The initially called Morris Liebmann Memorial Prize provided by the Institute of Radio Engineers (IRE), the IEEE Morris N. Liebmann Memorial Award was created in 1919 in honor of Colonel Morris N. Liebmann. It was initially given to awardees who h ...

*1958

IRE Medal of Honor The IEEE Medal of Honor is the highest recognition of the American Institute of Electrical and Electronics Engineers (IEEE). It has been awarded since 1917, and is presented to an individual or team of up to three who have made exceptional contri ...

by the

Institute of Radio Engineers The Institute of Radio Engineers (IRE) was a professional organization which existed from 1912 until December 31, 1962. On January 1, 1963, it merged with the American Institute of Electrical Engineers (AIEE) to form the Institute of Electrical ...

(IRE) "For outstanding scientific achievement and pioneering inventions and development in the field of electron tubes."

References

External links

National Academy of Sciences Biographical Memoir
* {{DEFAULTSORT:Hull, Albert 1880 births 1966 deaths 20th-century American inventors IEEE Medal of Honor recipients Yale University alumni Howard N. Potts Medal recipients Fellows of the American Physical Society People from Southington, Connecticut Presidents of the American Physical Society