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Description
A concept of a 16:1 500 MHz half Megawatt CW power combiner based on the rectangular WR1800 waveguide and its 4:1 prototype version are presented in this paper. This 16:1 combiner was developed for the solid state power amplifier and is supposed to be placed over the set of 19” amplifier racks.The combiner is designed to be modular and scalable, so that any number of input pairs can be added/excluded according to number of amplifier racks and hence output power needed. The 16:1 combiner has eight pairs of input EIA 4 ½” coaxial waveguide ports and ends with the accelerating cavity power coupler. The pairs of input coaxials are located on the wide side of the WR1800 waveguide at the wavelength distance between the pairs and end with coupling antennas.Several design options with antenna and loop inputs were considered during the R&D. The combiner is designed to handle 32 kW of the input power per port and 500 kW in total thus having the antenna water cooling system similar to [1]. Cooling is realized via a shortened 4 ½” line segment and RF power is loaded through the side line.
To check the chosen concept, a 4:1 prototype has been designed. The most critical elements of the 16:1 combiner - inputs, output, cooling system, tuning elements - are adopted to the 4:1 prototype to practice the performance and maintenance of these key nodes. A rectangular output of a “door-knob” type connector is used for prototype measurements.The side line for 4:1 prototype has a non 50 Ohm impedance region used for additional antenna matching. The mock-up combiner has a very wide ~50 MHz band and good phase and amplitude balance - less than 1% difference in Sn1 and 0.5 degrees in phase. This paper contains the results on 16:1 R&D and 4:1 prototype combiner electromagnetic design features, thermal simulation results and variational and tuning characteristics.
References
1. E. Rampnoux et al., DESIGN OF 352.21 MHz RF POWER INPUT COUPLER AND WINDOW FOR THE EUROPEAN SPALLATION SOURCE PROJECT (ESS), Proc. of SRF2013, Paris, France, pp.1069-1072.
| Young scientist paper | Yes |
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