Question: What American engineer and physicist taught at Princeton University and Massachusetts Institute of Technology and developed one of the first million-volt X-ray generators with John G. Trump?
Context: Certain works of structural engineering design are also works of structural art.  Such works can be classified as structural art when they attain excellence in the three areas of efficiency, economy, and elegance, as defined by Prof. David P. Billington of Princeton University.  A key part of the concept of structural art is that the structural engineer making the design must exercise his or her creativity and playfulness to create an elegant structure within the constraints imposed by engineering requirements.  These constraints include the safety and serviceability of the structure.  Therefore, a structure cannot be a successful work of structural art without also being a successful work of structural engineering design, yet many works of structural engineering design that are safe and serviceable do not rise to the level of structural art because they fail to be economical, efficient, or elegant.  Structural art is a topic of active scholarly research at several universities in the United States, including Princeton University, Tufts University, Bucknell University, University of Massachusetts Amherst, the Massachusetts Institute of Technology, and Roger Williams University, and in other parts of the world such as Spain (Universitat Politécnica de València) and Germany (HCU Hamburg).  While structural artists often collaborate with architects, the discipline of structural art is based upon engineering rather than architectural design.  A recent summary about this topic can be found in a review paper Li Bin is a senior associate working jointly in the Nuclear Policy Program and Asia Program at the Carnegie Endowment for International Peace.  He is a physicist with an interest in nuclear disarmament, and his research focuses on China’s nuclear and arms control policy and U.S.-China nuclear relations.  Previously, Li Bin was a professor of international relations at Tsinghua University, where he was the founding director of the Arms Control Program at the Institute of International Studies.  He has also directed the arms control division at the Institute of Applied Physics and Computational Mathematics.  Li Bin was a MacArthur Foundation Peace and Security Fellow at the Massachusetts Institute of Technology and Princeton University. Emily A. Carter (born November 28, 1960 in Los Gatos, California) is the Dean of the Princeton University School of Engineering and Applied Science and the Gerhard R. Andlinger Professor in Energy and the Environment, as well as a Professor in the Department of Mechanical and Aerospace Engineering and the Program in Applied and Computational Mathematics at Princeton University.  She is an associated faculty member in the Andlinger Center for Energy and the Environment, the Department of Chemistry, the Department of Chemical and Biological Engineering, the Princeton Institute for Computational Science and Engineering (PICSciE), the Princeton Environmental Institute (PEI), and the Princeton Institute for the Science and Technology of Materials (PRISM).  She was the Founding Director of the Andlinger Center for Energy and the Environment from 2010-2016.  Carter is a theorist and computational scientist whose work combines quantum mechanics, solid-state physics, and applied mathematics. John George Trump (August 21, 1907 – February 21, 1985) was an American electrical engineer, inventor, and physicist.  He was a recipient of U.S. President Ronald Reagan's National Medal of Science, and a member of the National Academy of Engineering.  John Trump was noted for developing rotational radiation therapy.  Together with Robert J. Van de Graaff, he developed one of the first million-volt X-ray generators.  He was the paternal uncle of U.S. President Donald Trump. Gene Michael Grossman (born December 11, 1955 in New York) is currently the Jacob Viner Professor of International Economics at Princeton University.  He received his B.A. in Economics from Yale University in 1976 and his Ph.D. in Economics from the Massachusetts Institute of Technology in 1980.  He became assistant professor at Princeton University in 1980 and full professor of economics in 1988.  His research focuses on international trade, in particular on the relationship between economic growth and trade and the political economy of trade policy.  He is also known for his work on the Environmental Kuznets Curve.  He frequently collaborated with Elhanan Helpman.  He is among the 100 best economists in the world according to IDEAS/RePEc.  In 2009, Gene Grossman received an honorary doctorate in Economics from the University of St. Gallen.  Grossman received the 2015 Onassis Prize for International Trade.  In 2016, Gene Grossman received an honorary doctorate in Economics from the University of Minho. The Journal of Accounting and Economics is a peer-reviewed academic journal focusing on the fields of accounting and economics.  The editors-in-chief are R. L. Watts (Massachusetts Institute of Technology), J. L. Zimmerman (University of Rochester), R. W. Holthausen (University of Pennsylvania), S. P. Kothari (Massachusetts Institute of Technology), J. Core (Massachusetts Institute of Technology), M. Hanlon (Massachusetts Institute of Technology), W. R. Guay (University of Pennsylvania), and J. Wu (University of Rochester). Marc Davis (born 1947) is an American Professor of Astronomy and Physics at the University of California, Berkeley.  Davis received his bachelor's degree from the Massachusetts Institute of Technology in 1969, his Ph.D from Princeton University in 1973 and has been elected to both the National Academy of Sciences (1991) and the American Academy of Arts and Sciences (1992).  Davis taught for a year at Princeton, 1973–74, then served on the Astronomy faculty at Harvard from 1975 to 1981.  Since 1981 he has been on the faculty of the Department of Astronomy and Physics at the University of California at Berkeley. Robert Duncan MacPherson (born May 25, 1944) is an American mathematician at the Institute for Advanced Study and Princeton University.  He is best known for the invention of intersection homology with Mark Goresky, whose thesis he directed at Brown University.  MacPherson previously taught at Brown University, the University of Paris, and the Massachusetts Institute of Technology.  In 1983 he gave a plenary address at the International Congress of Mathematicians in Warsaw. Anne-Marie Slaughter (born September 27, 1958) is an international lawyer, foreign policy analyst, political scientist and public commentator.  She received a B.A. from Princeton University in 1980, an M.Phil from Oxford University in 1982, a Harvard Law School, J.D. in 1985, and a D.Phil in International Relations from Oxford in 1992.  Most notably she is a member of the International Law Association, American Society of International Law, American Bar Association, American Academy of Arts and Sciences, and World Peace Foundation.  During her academic career, she has taught at Princeton University, the University of Chicago, and Harvard University.  From 2002 to 2009, she was the Dean of Princeton University's Woodrow Wilson School of Public and International Affairs and the Bert G. Kerstetter '66 University Professor of Politics and International Affairs.  She was subsequently the first woman to serve as the Director of Policy Planning for the U.S. State Department from January 2009 until February 2011 under U.S. Secretary of State Hillary Clinton.  She is a former president of the American Society of International Law and the current President and CEO of New America.  She married Princeton professor Andrew Moravcsik; they live in Princeton with their two sons. Robert Jemison Van de Graaff (December 20, 1901 – January 16, 1967) was an American engineer, physicist, and noted for his design and construction of high-voltage Van de Graaff generators.  He taught at Princeton University and Massachusetts Institute of Technology.
Answer: Robert J. Van de Graaff