Brillouin flow electron gun
Charles K. Birdsall
U.S. Patent 2,817,035. December 1957

Traveling-wave tube
George R. Brewer, Horace R. Johnson and Charles K. Birdsall
U.S. Patent 2,811,663. October 1957

Microwave tube
Charles K. Birdsall
U.S. Patent 2,811,641. October 1957

Resistive-inductive wall amplifier tube
Andrew V. Haeff and Charles K. Birdsall
U.S. Patent 2,793,315. May 1957