Bussard worked on a promising new type of inertial electrostatic confinement (IEC) fusor, called the Polywell, that has a magnetically shielded grid (MaGrid). He founded Energy/Matter Conversion Corporation, Inc. (EMC2) in 1985 to validate his theory, and tested several (15) experimental devices from 1994 through 2006. The U.S. Navy contract funding that supported the work expired while experiments were still small. However, the final tests of the last device, WB-6, reputedly solved the last remaining physics problem just as the funding expired and the EMC2 labs had to be shut down.
Further funding was eventually found, the work continued and the WB-7 prototype was constructed and tested, and the research is ongoing.