Question: What was the contribution made by de Graaff to the technology John Trump and Robert Van de Graaff developed together?
Sentence (from "Robert J. Van de Graaff"): 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.
Relevant evidence: Yes