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ReseaRch a n d developmenT In T h e aR m y 29
X-rays consist of high-frequency electromagnetic radiation. They are
produced when electrons are accelerated to high energies through a large voltage
potential in an evacuated chamber. Until World War II, modified vacuum
tubes were the most common X-ray sources, and they were widely used by
medical practitioners in hospitals to diagnose and treat diseases. Operational
ranges typically did not exceed two million electron volts. New types of particle
accelerators capable of generating much higher voltages, both for scientific study
and clinical use, began to appear in the 1930s, when nuclear physics began to
capture the interest of the American scientific community. One of the first
practical high-energy electron accelerators, known as the betatron, was invented
at the University of Illinois in 1940, and it was transformed into a powerful
X-ray source at the research laboratory of the General Electric Company during
the war. 47 Conventional X-ray tubes and the far more powerful betatrons were
employed extensively in the Army’s arsenal system before and after the war.
Unlike their counterparts in academia, who by and large used these instruments
to study the structure and behavior of atoms and molecules, arsenal researchers
conducted X-ray studies to solve urgent practical problems related to ordnance
development and production.
Nestled on the upper Mississippi River between Iowa and Illinois, the
Ordnance Department’s Rock Island Arsenal served as a major center for applied
X-ray research dating back to the 1930s. After World War II, the arsenal’s primary
products included mortars, light and medium artillery, gun carriages, and rocket
and guided missile launchers. Rock Island also overhauled and rebuilt weapons
already operating in the field. The research that supported these manufacturing
and maintenance functions had always been and continued to be narrowly focused
on production problems. Research for its own sake was not part of Rock Island’s
mission officially, nor that of any of the other Army arsenals. Rock Island engineers,
for example, drafted the initial plans and specifications for the 3.5-inch rocket
launcher (also known as the “super bazooka”), and the arsenal also turned out the
first prototypes scheduled for testing and debugging prior to mass production by
industrial contractors. 48 The first quantities of this new antitank weapon entered
service with American combat forces shortly after the outbreak of hostilities in
Korea. Similar procedures guided the development of other weapon systems, such
as the Army’s first mobile, large-caliber launcher for the Honest John rocket and a
helicopter-mounted, single-rail rocket launcher for the Little John rocket. 49
During the immediate postwar period, the bulk of research and development
at Rock Island was scattered throughout the arsenal’s manufacturing divisions.
47 See J. L. Heilbron and Robert W. Seidel, Lawrence and his Laboratory, vol. 1 of A History of the Lawrence
Berkeley Laboratory (Berkeley: University of California Press, 1989). On the origins of the betatron, see D. W.
Kerst, “Historical Development of the Betatron,” Nature 157 (26 January 1946): 90–95.
48 Engineers at Picatinny Arsenal also contributed to the development of the 3.5-inch rocket launcher.
See “Rockets at Picatinny Arsenal,” 114.
49 Rock Island Arsenal began producing rocket launchers in 1942. W. W. Warner, “Arsenals in Action,”
Army Information Digest 6 (September 1951): 39–40; M. S. Werngren, “Skills Spell Strength,” Army
Information Digest 17 (September 1962): 62; Neil M. Johnson and Leonard C. Weston, Development and
Production of Rocket Launchers at Rock Island Arsenal, 1945–1959 (Rock Island, Ill.: U.S. Army Weapons
Command, 1962), 1, 8–9.