Albert Hull
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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, 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. The type kn ...
s, and invented the
magnetron The cavity magnetron is a high-power vacuum tube used in early radar systems and currently in microwave ovens and linear particle accelerators. It generates microwaves using the interaction of a stream of electrons with a magnetic field while ...
. He was a member of the
National Academy of Sciences The National Academy of Sciences (NAS) is a United States nonprofit, 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 Nati ...
.


Biography

He was born on 19 April 1880 in
Southington, Connecticut Southington is a town in Hartford County, Connecticut, United States. As of the 2020 United States Census, it had a population of 43,501. Southington contains the villages of Marion, Milldale, and Plantsville. Geography Southington is situ ...
. He majored in
Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...
and after taking one undergraduate course in
physics Physics is the natural science that studies matter, its 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 which r ...
, graduated from
Yale University Yale University is a private research university in New Haven, Connecticut. Established in 1701 as the Collegiate School, it is the third-oldest institution of higher education in the United States and among the most prestigious in the wo ...
. He taught languages at
The Albany Academy The Albany Academy is an independent college preparatory day school for boys in Albany, New York, USA, enrolling students from Preschool (age 3) to Grade 12. It was established in 1813 by a charter signed by Mayor Philip Schuyler Van Renssela ...
before returning to Yale, to take a doctorate in
physics Physics is the natural science that studies matter, its 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 which r ...
. He then undertook research on photoelectricity whilst teaching physics for five years at the
Worcester Polytechnic Institute '' , mottoeng = "Theory and Practice" , established = , former_name = Worcester County Free Institute of Industrial Science (1865-1886) , type = Private research university , endowme ...
. In 1914 Hull joined the
General Electric General Electric Company (GE) is an American multinational conglomerate founded in 1892, and incorporated in New York state and headquartered in Boston. The company operated in sectors including healthcare, aviation, power, renewable energ ...
Research Laboratory (GERL) in
Schenectady, New York Schenectady () is a city in Schenectady County, New York, United States, of which it is the county seat. As of the 2020 census, the city's population of 67,047 made it the state's ninth-largest city by population. The city is in eastern New Y ...
and remained there until his retirement in 1949. During 1916, Hull began investigation into the use of magnetic control of
thermionic valves A vacuum tube, electron tube, 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 potential difference has been applied. The type known as a ...
(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 k ...
in 1942. He retired from
General Electric Research Laboratory General Electric Research Laboratory was the first industrial research facility in the United States. Established in 1900, the lab was home to the early technological breakthroughs of General Electric and created a research and development environm ...
(GERL) in 1949. He did consulting work and served on an
advisory committee An advisory board is a body that provides non-binding strategic advice to the management of a corporation, organization, or foundation. The informal nature of an advisory board gives greater flexibility in structure and management compared to th ...
of the Army
Ballistic Research Laboratory The Ballistic Research Laboratory (BRL) was a leading U.S. Army research establishment situated at Aberdeen Proving Ground, Maryland that specialized in ballistics ( interior, exterior, and terminal) as well as vulnerability and lethality analysis. ...
after retirement from General Electric. He died on 22 January 1966 at the age of 85 in
Schenectady, New York Schenectady () is a city in Schenectady County, New York, United States, of which it is the county seat. As of the 2020 census, the city's population of 67,047 made it the state's ninth-largest city by population. The city is in eastern New Y ...
.


Dynatron

He invented the dynatron vacuum tube which had three electrodes: a
thermionic cathode In vacuum tubes and gas-filled tubes, a hot cathode or thermionic cathode is a cathode electrode which is heated to make it emit electrons due to thermionic emission. This is in contrast to a cold cathode, which does not have a heating element. ...
, 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
magnetron The cavity magnetron is a high-power vacuum tube used in early radar systems and currently in microwave ovens and linear particle accelerators. It generates microwaves using the interaction of a stream of electrons with a magnetic field while ...
. This took the form of a central cathode and a
coaxial In geometry, coaxial means that several three-dimensional linear or planar forms share a common axis. The two-dimensional analog is ''concentric''. Common examples: A coaxial cable is a three-dimensional linear structure. It has a wire conduc ...
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 Henry Albert Howard Boot (29 July 1917 – 8 February 1983) was an English physicist who with Sir John Randall and James Sayers developed the cavity magnetron, which was one of the keys to the Allied victory in the Second World War. Biography ...
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 detection system that uses radio waves to determine the distance (''ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, w ...
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
thyratron A thyratron is a type of gas-filled tube used as a high-power electrical switch and controlled rectifier. Thyratrons can handle much greater currents than similar hard-vacuum tubes. Electron multiplication occurs when the gas becomes ionized, pro ...
s (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 The Howard N. Potts Medal was one of The Franklin Institute Awards for science and engineering award presented by the Franklin Institute of Philadelphia, Pennsylvania. It is named for Howard N. Potts. The first Howard N. Potts Medal was awarded in ...
of the
Franklin Institute The Franklin Institute is a science museum and the center of science education and research in Philadelphia, Pennsylvania. It is named after the American scientist and statesman Benjamin Franklin. It houses the Benjamin Franklin National Memori ...
. *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 Institute of Electrical and Electronics Engineers (IEEE). It has been awarded since 1917, when its first recipient was Major Edwin H. Armstrong. It is given for an exceptional contributio ...
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 a ...
(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