Question: Charles Louis Critchfield earned his PhD in Physics from George Washington University under the direction of which theoretical physicist who was known as "the father of the hydrogen bomb."
Context: The W21 was an hydrogen bomb design for the US military.  It would have used the physics package of the TX-21 bomb.  The TX-21 was a weaponized version of the "Shrimp" device tested in the Bravo shot of Operation Castle.  A TX-21C was tested as the Navajo shot, Operation Redwing.  The TX-21, was a scaled-down version of the Runt device (M-17 hydrogen bomb).  Smaller in size and weight to the Mk-17, the Mk-21 was considered as a potential missile warhead.  Far more powerful than the TX-13, which was a high-yield atomic bomb developed from the Mk-6 bomb, the XW21 was to replace the XW13 in the weapons pod of the B-58 bomber and for the SM-64 Navaho missile. This article is a list of things named after Edward Teller Hungarian-American theoretical physicist, regarded by some as "the father of the hydrogen bomb". Jordan Carson Mark (July 6, 1913 – March 2, 1997) was a Canadian-born mathematician best known for his work on developing nuclear weapons for the United States at the Los Alamos National Laboratory.  Mark joined the Manhattan Project in 1945, and continued to work at Los Alamos under the leadership of Norris Bradbury after World War II ended.  He became the leader of the Theoretical Division at the laboratory in 1947, a position he held until 1973.  He oversaw the development of new weapons, including the hydrogen bomb in the 1950s.  On the hydrogen bomb project he was able to bring together experts like Edward Teller, Stanislaw Ulam and Marshall Holloway despite their personal differences. James Goldgeier is a professor of international relations at the School of International Service at American University in Washington, DC., where he served as Dean from 2011-2017.  He became dean in August 2011.  Previously he was employed at George Washington University in Washington, DC, as professor of political science and international affairs (2004-2011), associate professor of political science and international affairs (1998-2004), and assistant professor of political science and international affairs (1994-1998).  While at George Washington University, he also served as Director of the Institute for European, Russian and Eurasian Studies (2001-2005), for which he had previously served as acting director (1999-2000).  Before joining George Washington University, he taught at Cornell University (1991-1993).  He is often considered a doppelganger of Tom Hanks due to his similar voice and appearance. Edward Teller (Hungarian: "Teller Ede" ; January 15, 1908 – September 9, 2003) was a Hungarian-American theoretical physicist who was born in Hungary, and is known colloquially as "the father of the hydrogen bomb", although he claimed he did not care for the title.  He made numerous contributions to nuclear and molecular physics, spectroscopy (in particular the Jahn–Teller and Renner–Teller effects), and surface physics.  His extension of Enrico Fermi's theory of beta decay, in the form of Gamow–Teller transitions, provided an important stepping stone in its application, while the Jahn–Teller effect and the Brunauer–Emmett–Teller (BET) theory have retained their original formulation and are still mainstays in physics and chemistry.  Teller also made contributions to Thomas–Fermi theory, the precursor of density functional theory, a standard modern tool in the quantum mechanical treatment of complex molecules.  In 1953, along with Nicholas Metropolis, Arianna Rosenbluth, Marshall Rosenbluth, and Augusta Teller, Teller co-authored a paper which is a standard starting point for the applications of the Monte Carlo method to statistical mechanics. Emil Julius Klaus Fuchs (29 December 1911 – 28 January 1988) was a German theoretical physicist and atomic spy who, in 1950, was convicted of supplying information from the American, British, and Canadian Manhattan Project to the Soviet Union during and shortly after the Second World War.  While at the Los Alamos National Laboratory, Fuchs was responsible for many significant theoretical calculations relating to the first nuclear weapons, and later, early models of the hydrogen bomb. Marcus Ward Lyon Jr. (February 5, 1875 – May 19, 1942) was an American mammalogist, bacteriologist, and pathologist.  He was born into a military family, and demonstrated an early interest in zoology by collecting local wildlife around his father's army posts.  He graduated from Brown University in 1897, and continued his studies at George Washington University while working part-time at the United States National Museum (USNM).  At the same time, he taught at Howard University Medical School and later George Washington University Medical School.  He received his Ph.D. from George Washington University in 1913.  In 1919, he and his wife, Martha, moved to South Bend, Indiana to join a newly opened clinic.  Prior to moving, Lyon had published many papers on mammalogy, both during and after his tenure at the USNM.  In these papers, he had formally described six species, three genera, and one family.  Once in South Bend, he began to publish medical studies, too, but continued his work in mammalogy, with a particular focus on the local fauna of Indiana.  He published more than 160 papers during his career. Vitaly Lazarevich Ginzburg, (Russian: Вита́лий Ла́заревич Ги́нзбург ; 4 October 1916 – 8 November 2009) was a Soviet and Russian theoretical physicist, astrophysicist, Nobel laureate, a member of the Soviet and Russian Academies of Sciences and one of the fathers of the Soviet hydrogen bomb.  He was the successor to Igor Tamm as head of the Department of Theoretical Physics of the Lebedev Physical Institute of the Russian Academy of Sciences (FIAN), and an outspoken atheist. This is a list of notable George Washington University faculty, including both current and past faculty at the Washington, D.C. school, as well as university officials.  As of 2007, The George Washington University employs approximately 1,130 full-time , in addition to part-time, faculty members across its three campuses.  Presidents John Quincy Adams and Ulysses Grant served on the Board of Trustees, as did Attorney General Eric Holder.  Professors have been government officials, leading scientists, and others.  Edward Teller, a physicist considered the father of the hydrogen bomb taught at GW.  Frank Sesno, a CNN Special Correspondent, currently teaches in that field and since Fall of 2009, will be the Director of the School of Media and Public Affairs.  The current President of the University is Thomas LeBlanc. Charles Louis Critchfield (June 7, 1910 – February 12, 1994) was an American mathematical physicist.  A graduate of George Washington University, where he earned his PhD in Physics under the direction of Edward Teller in 1939, he conducted research in ballistics at the Institute for Advanced Study in Princeton and the Ballistic Research Laboratory at the Aberdeen Proving Ground, and received three patents for improved sabot designs.
Answer: Edward Teller