Efficiency improvement of the traveling-wave interaction process

Experimental evidence that conventionally designed, uniform-period traveling-wave amplifiers are potentially highly efficient devices is presented. Experiments with a traveling-wave re-entrant cavity tube and with a two-helix tube show that substantial improvement is possible when the RF energy of the so-called beam of a saturated traveling-wave tube is used. Tests reported here on the two-helix tube realized efficiencies greater than 43 percent.