A Self-Biasing Pulsed Depressed Collector

Retrofitting the 5045 klystron for higher efficiency

“…When a final design is settled upon, a retrofitted 5045 will be constructed and tested. A pulsed depressed collector [2] will be developed in conjunction with the aforementioned changes to the circuit with the goal of achieving an overall 80%+ tube efficiency…”

“…The 5045 klystron design has remained largely unchanged over the last couple decades. Although the design is robust, improvements could be made, such as using a pulsed depressed collector to improve efficiency [2]. Improvements in the circuit could also be made to increase the efficiency of the device and to produce a more monoenergetic beam which would be well suited for depressed collector design.…”

A pulsed depressed collector for a 5 MW S-band klystron

“…This modulator recovers energy during one pulse, and resonates the energy back to the main driving modulator during the inter pulse period. In this way, the driving and recovery modulators are decoupled during the pulse [2]. Collector stages must be biased at potentials approaching the beam voltage (100's kV), while typical modulators store energy between 1 and 25kV.…”

“…This technique has been demonstrated on a low power tube. Efforts are currently underway to apply this technology to the 5.5 MW CPI VKS-8262S and the 65 MW SLAC 5045 (see Table I) [2,3].…”

Inverse Marx modulators for self‐biasing klystron depressed collectors

“…During the pulse, a step‐down transformer builds up energy in a storage capacitor. This energy is then recovered back to the driving modulator in the inter‐pulse time period [2]. This Letter proposes an alternative biasing topology: the ‘inverse’ Marx modulator.…”