SPS Feasability Study SD76SA0239-2

Figure 2.3-2 shows a simplified block diagram of a mod-anode klystron. The mod-anode klystron structure is simply the normal anode insulated from the body of the tube. Separated in this fashion, the mod-anode may be used in a number of ways to provide klystron control and protection. Moreover, by suitable techniques, the electron gun voltage may be reduced significantly from the higher voltage necessary in the usual design. For example, a low- voltage, high-current electron gun may be employed. Post-electron-gun acceleration of the electron beam may then be used to obtain the final desired beam voltage and microperveance. Properly designed, the mod-anode is essentially a zero current electrode, and the control voltage power supply furnishes voltage but no power to effect control. The resistance R may be of a high value, perhaps 100,000 ohms, since no current is drawn by the mod-anode. The key problem of the klystron system as shown by the mod-anode design will be the power supply requirements. Using multiple depressed collectors, various power supply voltages may complicate the de power distribution and regulation system. The requirements for various de regulation and levels must be determined to determine future system impact. Rockwell's in-house efforts on the MW antenna indicated potential efficiency increases and weight savings are possible if RF and thermal radiators can be combined as one integral unit. Rockwell has developed a resonant cavity radiator concept (RCR) which is a modification of the conventional slotted common wall waveguide radiator, with the inner walls removed. The resonant cavity radiator, which operates in the TEmo mode, is designed for higher kF efficiency and lower weight than the conventional waveguide. Since Figure 2.3-2. Simplified Diagram of Klystron Mod-Anode and Beam Power Requirements