Robert J. Van de Graaff

Robert Jemison Van de Graaff (December 20, 1901 – January 16, 1967) was an American applied physicist and inventor. He is best known for developing the Van de Graaff generator, a high-voltage electrostatic machine that became a fundamental tool in nuclear physics research.

Raised in Tuscaloosa, Alabama, Van de Graaff earned his DPhil degree at Oxford as a Rhodes Scholar. In Europe, exposure to Marie Curie, Ernest Rutherford, and J. Robert Oppenheimer encouraged him to develop methods for accelerating particles to nuclear energies. He built his first electrostatic generator at Princeton University in 1929 and demonstrated a 1.5-million-volt model in 1931, more than twice the highest direct current voltage previously achieved. After joining the Massachusetts Institute of Technology he constructed the 5-megavolt Round Hill generator. He collaborated with John G. Trump, his former student, on creating compact, gas-insulated machines, which became the first accelerators used in clinical medicine. During World War II, he directed development of high-voltage X-ray equipment for the U.S. Navy.

A high school football injury, aggravated by wartime overwork and later accidents, left Van de Graaff with chronic health problems in his later career. Nevertheless, in 1946 he joined Trump and Denis M. Robinson in organizing the High Voltage Engineering Corporation, the first company to manufacture particle accelerators. As Chief Scientist, he guided development of commercial accelerators. In the 1950s, he invented the insulating-core transformer and was instrumental in commercializing HVEC's tandem accelerators. By 1967, more than 500 high-voltage Van de Graaff generators were operating worldwide, and HVEC had installed accelerators in hospitals and labs in 30 countries. He received the Tom W. Bonner Prize in 1966 for his contributions to electrostatic accelerator development.

Early life and education

Robert Jemison Van de Graaff was born on December 20, 1901, at the Jemison–Van de Graaff Mansion in Tuscaloosa, Alabama, the youngest of four sons of Adrian Sebastian Van de Graaff and Minnie Cherokee Jemison. The family had deep roots in Alabama: his great-grandfather was Robert Jemison Jr., a slaveholder planter and former state senator, and his father, a circuit judge, had been a substitute on Yale's first 11-man football team. The elder Van de Graaff became a professor of law at the University of Alabama in 1891.

thumb|left|150px|Quarterback injuries, age 15

Van de Graaff's three older brothers—Adrian, Hargrove, and William—became celebrated football players for the Alabama Crimson Tide, and William became Alabama's first All-American player in 1915. Robert intended to follow them: as a sophomore at Tuscaloosa High School, he played quarterback on the team coached by his brother Adrian. However, in the fall of 1917, during his senior year, he suffered a severe injury while playing, breaking his femur and severely injuring his back. He spent the rest of his senior year recuperating in the mansion, reading books about engines to pass the time, and never graduated from high school.

Despite his injuries, Van de Graaff enrolled at the University of Alabama in the fall of 1918, remaining on crutches for much of his freshman year. He joined the "Scrubs" (reserve team), coached by his brothers Adrian and Hargrove after their return from World War I, and played left end in games against Georgia Tech and Mississippi A&M. But he came to realize he would not match his brothers' athletic achievements. Years later, he recalled that a young woman asked how football was going, he replied, "It's not my game." She asked, "Well, Robert, what is your game?" He later recounted this as a life-changing moment that redirected him toward science.

In February 1921, Van de Graaff petitioned with eleven other students to become charter members of the University of Alabama's Theta Tau engineering fraternity. He became studious and made the honor roll for the first time. His lifelong nickname, "Tee," derived from his habit of drinking tea to stay alert while studying all night before exams. During summers, he worked on steamboats navigating the Black Warrior River, cultivating an interest in engines.

Van de Graaff received a B.S. degree (1922) and M.S. degree (1923) in mechanical engineering from the University of Alabama. For his master's degree thesis, he developed an improved system for mining lower grades of iron ore, in which ore moved on a conveyor belt and the more ferromagnetic components were extracted by a high magnetic field at a sharp metallic tip—a concept that anticipated aspects of his later inventions. After graduation, he worked for a year at the Alabama Power Company as a research assistant, where he observed that hydroelectric generators could operate with much larger gaps in their magnetic circuits than he had believed possible. This observation that would later inform his invention of the insulating core transformer.

Studies in Europe

thumb|left|200px|Marie Curie's lectures, in which [[Irène Curie demonstrated particle decay, sparked Van de Graaff's experimental interests.]]

With a grant from the state of Alabama, Van de Graaff traveled to Paris in 1924 to study at the Sorbonne. There he attended lectures by Marie Curie on radioactivity and became fascinated by the clicks of individual alpha particles detected by a Geiger counter—an experience he later cited as inspiring his life's work. At the Sorbonne, Van de Graaff realized that atomic nuclei are electrically charged, therefore electrostatic high voltages could accelerate particles over the nuclear potential barrier and into the nucleus.

In 1925, Van de Graaff won a Rhodes Scholarship to The Queen's College at the University of Oxford. At Oxford, Van de Graaff studied under J. S. E. Townsend and felt intimidated by the erudition of his colleagues, who typically spoke three languages fluently. He continued to participate in sports despite his leg injury, playing lacrosse and receiving a "blue" in rowing. He earned a second B.S. degree in physics in 1926 and a DPhil degree in 1928.

While at Oxford, Van de Graaff had his first extended opportunity to discuss accelerator physics with a peer. In 1926, he shared a room for a week at Leiden University with J. Robert Oppenheimer, then also a graduate student. The two talked late into the night, Oppenheimer about theoretical aspects of proton scattering and Van de Graaff about possibilities for electrostatic accelerators.

Van de Graaff later read Ernest Rutherford's 1927 anniversary address to the Royal Society, in which Rutherford expressed his ambition "to have available... a copious supply of atoms and electrons... transcending in energy the alpha and beta particles from radioactive substances." According to Van de Graaff, this address increased his conviction that an approach to generating high voltages was needed for progress in nuclear research.

Career

Princeton (1929–1931)

thumb|220px|right|Van de Graaff demonstrated his $100 generator in Nov. 1931

In September 1929, Van de Graaff returned to the United States as a National Research Fellow at Princeton University, expressly to develop a high-voltage source. That fall, he built a rudimentary proof-of-concept from "a tin can, a silk ribbon, and a small motor, at no expense." This simple model could sustain 80 kV, limited by discharge from the can's edges. With encouragement from Karl Taylor Compton, head of the physics department, he developed this concept further.

On March 20, 1931, after a sleepless night and many preliminary drafts, Van de Graaff wrote to Compton outlining his vision for the scientific applications of his generator. He predicted that proton bombardment of uranium might precipitate disintegration or that "the proton would be captured by the nucleus, thus opening up the possibility of creating new elements of atomic number greater than 92"—eight years before the first transuranium element was synthesized. In the same letter, he predicted the nuclear reaction that would result from proton bombardment of lithium. (One year later, John Cockcroft and Ernest Walton demonstrated this reaction, for which they received the 1951 Nobel Prize in Physics.)

Van de Graaff built a larger demonstration model with $100 in department funds. By November 1931, the model was producing more than 1.5 million volts—more than twice the highest direct current voltage previously achieved. He publicly demonstrated this device at the inaugural dinner of the American Institute of Physics, with Compton at his side as he "nervously explained the principles of his invention." Van de Graaff observed that, paired with a discharge tube yet to be designed, his device offered a "powerful means for the investigation of the atomic nucleus and other fundamental problems."

The demonstration prompted rapid adoption of the design. Merle Tuve, who was developing acceleration tubes with Lawrence Hafstad and Odd Dahl at the Department of Terrestrial Magnetism (DTM) of the Carnegie Institution, immediately borrowed Van de Graaff's machine and drove it to Washington DC. By October 1931, the DTM group had tested the generator to 800 kV and begun constructing a larger unit; by November 1932, their improved machine became the first Van de Graaff accelerator used in nuclear experiments. At the University of Wisconsin, graduate student Ray Herb began work on a pressurized Van de Graaff in 1933. Westinghouse Research Laboratories later constructed a 4-megavolt pressurized unit.

Massachusetts Institute of Technology (1931–1960)

Round Hill generator

When Compton became president of the Massachusetts Institute of Technology in 1930, he arranged for Van de Graaff to join MIT as a research associate in 1931. With support from Compton and a grant from the Research Corporation, Van de Graaff and his associates—including physicists Lester C. Van Atta and Chester M. Van Atta—undertook construction of a much larger, air-insulated generator. Compton arranged for the project to be housed in a former airship hangar at the Round Hill estate of Colonel E. H. R. Green in South Dartmouth, Massachusetts. Van de Graaff hoped the machine would be the first to artificially split the atom, but John Cockcroft and Ernest Walton accomplished the feat with a voltage multiplier circuit in 1932, while the Round Hill generator was still under construction.

thumb|200px|The -tall [[Round Hill generator]]

On November 28, 1933, the first full-scale test produced sparks long for an audience of scientists and journalists. In March 1934, Nikola Tesla wrote a cover story on the generator for Scientific American, observing that it represented "a distinct advance over its predecessors," which included his own Tesla coil.

The Round Hill site proved difficult for sustained research. Designed to reach 10 megavolts, the generator achieved only 5.1 megavolts due to problems with air insulation; humidity, salt fog, and contamination on the terminal spheres caused electrical breakdown. No nuclear experiments were completed at Round Hill, in part because it took nearly four years to design an acceleration tube that could control a particle beam. D. Allan Bromley later concluded that "although performance of the Round Hill generator was disappointing to Van de Graaff the experience gained with this machine was invaluable to later designs."

In 1934, Van de Graaff was appointed Associate Professor of Physics at MIT, a position he held until 1960. Following Colonel Green's death in 1936, Round Hill closed, and the generator was moved to the MIT campus in 1937, where it was completely redesigned. The reconfigured machine operated at lower but more stable voltages and incorporated one of the first remote control systems for high-voltage equipment. The generator remains operational and on permanent display at the Boston Museum of Science.

Early applications

Around 1931, at Bush's suggestion, Van de Graaff began collaborating with John G. Trump, then a doctoral student in electrical engineering. This collaboration lasted until Van de Graaff's death. Together they explored applications beyond nuclear physics. Van de Graaff developed ideas for high-voltage DC power transmission; Trump's dissertation showed that a vacuum-insulated line could transmit a gigawatt over with only 2.5% energy loss. Trump also pioneered medical uses: in 1937, Harvard's Huntington Memorial Hospital approved construction of a mega-volt X-ray generator for cancer treatment, the first use of an electrostatic accelerator in clinical medicine.

Van de Graaff and Trump's research generated patenting activity that later historians have identified as an important precedent in university technology transfer. Because Van de Graaff had developed his ideas across multiple institutions, the Research Corporation organized a three-way agreement in 1933 among Princeton, MIT, and the National Research Council to secure clear title to his patents. The power transmission concept attracted interest from the Tennessee Valley Authority, which in 1933 considered funding MIT $250,000 to develop the technology. However, the project collapsed amid technical uncertainties and political disagreements over patent terms.

The pattern persisted through the war: Van de Graaff's patents attracted repeated industrial interest, but no commercial results. General Electric, Picker X-ray Corporation, and Westinghouse each pursued licenses, yet negotiations failed. Large firms demanded exclusive rights to justify their investment, but MIT's 1932 patent policy, which treated licensing as a public trust, made the university reluctant to grant them.

World War II radiography

Van de Graaff machines were widely used for wartime science and production. In 1940, a 2 MV machine originally destined for a Philadelphia hospital was requisitioned for the Manhattan Project and sent to Chicago for Enrico Fermi's work on the nuclear pile. Shortly after the United States entered World War II, Van de Graaff volunteered for war-related work and was appointed Director of the High Voltage Radiographic Project at MIT. He directed the development of high-voltage X-ray equipment for industrial and military radiography, including the examination of heavy ordnance for the U.S. Navy. His laboratory built five 2 MV X-ray generators, sold to the Navy at $100,000 each. The U.S. Navy recognized Van de Graaff and eight of his associates with Naval Ordnance Development Awards.

The combination of wartime work and his old football injury caused a breakdown in Van de Graaff's health that lasted for several years after the war. His physical difficulties were compounded by further misfortune: an operation in the 1940s or 1950s left him with hepatitis from a contaminated blood transfusion. In the 1950s he was severely injured in an automobile accident, breaking his legs again. According to his son, the cumulative injuries were so severe that Van de Graaff spent much of his later life working from a bed, maintaining one in his office and another at home. A colleague later wrote that Van de Graaff "bore this difficult period with uncomplaining courage and optimism," but that he "sank in all but name very much into the background, as the exciting events of physics unfolded in the years immediately following the war."

ONR generator

After recovering his health, Van de Graaff collaborated with William W. Buechner on the construction of a 12 MV electrostatic generator in Building 58 during the 1948–1952 period. Under Buechner's direction, this facility conducted a substantial fraction of all precision nuclear spectroscopy accomplished during its operating lifetime.

High Voltage Engineering Corporation (1946–1967)

By 1946, the original generator patent had only six years remaining before expiration, with no royalties yet generated. Failure to license the patent set the stage for a new idea: a university spin-off.

Trump proposed forming a new company to manufacture and sell electrostatic accelerators. In late 1946, he co-founded the High Voltage Engineering Corporation (HVEC) with Van de Graaff and Denis Robinson. Trump served as Technical Director and Chairman of the Board, Robinson as President, and Van de Graaff as Chief Scientist. The American Research and Development Corporation, a pioneer of institutional venture capital, provided the company's initial funding; Van de Graaff held a 13 percent equity stake. HVEC was the first company organized with the express purpose of manufacturing particle accelerators. When HVEC exited the accelerator business in 1983, the ICT technology was adopted by several successor firms, including Cryovac, Vivirad, Nissin-High Voltage, and Wasik Associates.

The Van de Graaff crater on the far side of the Moon is named after him.

Recognition

Memberships

{| class="wikitable"

! Country

! Year

! Institute

! Type

| 1934

| American Physical Society

| Fellow

| 1935

| American Academy of Arts and Sciences

| Member

Awards

{| class="wikitable"

! Country

! Year

! Institute

! Award

! Citation

| 1936

| Franklin Institute

| Elliott Cresson Medal

| "High voltage electrostatic generator"

| 1945

| U.S. Navy Bureau of Ordnance

| Naval Ordnance Development Award

| 1947

| Institute of Physics

| Duddell Medal and Prize

| 1966

| American Physical Society

| Tom W. Bonner Prize

| "For his contributions to and continued development of the electrostatic accelerator"

Works

Journal articles

Patents

– "Electrostatic Generator" (1931)
– "Electrical Transmission System" (1932)
– "Method of and apparatus for electrostatically generating direct current power" (1937, with John G. Trump)
— "Apparatus for neutron detection" (1953)
— "Unidirectional high-voltage generator" (1956)
— "Apparatus For Reducing Electron Loading In Positive-Ion Accelerators" (1958)
– "High Voltage Electromagnetic Apparatus Having An Insulating Magnetic Core" (1961)
— "Multi-Disk Electromagnetic Power Machinery" (1960)
– "Inclined field High Voltage Vacuum Tubes" (1962)
– "High Voltage Electromagnetic Charged-Particle Accelerator Apparatus Having An Insulating Magnetic Core" (1965)

Notes

References

Citations

External links