The Bifield-Brown effect is an anomalous physics principle at the heart of this story, and it also invites the most controversy.
For example, in 1990, the Air Force tested a Bifield-Brown experiment in a vacuum, but they only used 19 kilovolts instead of the megavoltage Brown was using.
As Brown said after the experiment himself, in short, it appears there is strong evidence that the Bifield-Brown effect does exist in the negative to positive direction in a vacuum of at least 10 to the negative 6th torr.