| Paper | Title | Page |
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| WEPMN100 | RF Design and Processing of a Power Coupler for Third Harmonic Superconducting Cavities | 2265 |
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Funding: U. S. Department of Energy The FLASH user facility providing free electron laser radiation is built based on the TTF project at DESY. Fermilab has the responsibility for the design and processing of a third harmonic, 3.9 GHz, superconducting cavity which is powered via a coaxial power coupler. Six power couplers have been manufactured at CPI after successful design of the power coupler including RF simulation, multipacting calculation, and thermal analysis. The power couplers are being tested and processed with high pulsed power in an elaborate test stand at Fermilab now. This paper presents the RF design and processing work of the power coupler. |
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| WEPMN101 | Coupling Interaction Between the Power Coupler and the Third Harmonic Superconducting Cavity | 2268 |
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Funding: U. S. Department of Energy Fermilab has developed a third harmonic superconducting cavity operating at the frequency of 3.9 GHz to improve the beam performance for the FLASH user facility at DESY. It is interesting to investigate the coupling interaction between the SRF cavity and the power coupler with or without beam loading. The coupling of the power coupler to the cavity needs to be determined to minimize the power consumption and guarantee the best performance for a given beam current. In this paper, we build and analyze an equivalent circuit model containing a series of lumped elements to represent the resonant system. An analytic solution of the required power from the generator as a function of the system parameters has also been given based on a vector diagram. |
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| THPMN088 | C-Band High Power RF Generation and Extraction Using a Dielectric Loaded Waveguide | 2912 |
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Funding: Department of Energy
We report on the fabrication, simulation, and high-power testing of a C-band RF power extractor recently conducted at the Argonne Wakefield Accelerator (AWA) facility. Dielectric loaded accelerating (DLA) structures can be used for high-power RF generation [*,**] when a high-current electron beam passes through a DLA structure and loses energy into the modes of the structure due to self-wakefields. The AWA generates high charge (up to 100nC), short bunch length (1.5mm~2.5mm) electron beams, which is ideal for high-power RF generation. The generated RF power can be subsequently extracted with a properly designed extraction coupler in order to accelerate a second beam, or for other high power purposes. In this paper, the detailed design of a 7.8 GHz DLA power extractor, MAFIA simulations, and results of the high-power test are presented. Simulation predictions of an 79 MW, 2.2 ns long RF pulse (generated by a single 100 nC electron bunch) and a longer RF pulse of the same power (obtained from a 35 nC periodic bunch train) will be compared to experimental results.
* W. Gai, et al, Experimental Demonstration of Two Beam Acceleration Using Dielectric Step-up Transformer, PAC01, pp.1880-1882.** D. Yu, et al, 21GHz Ceramic RF Power Extractor, AAC02, pp.484-505. |
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| THPMN092 | Design and Prototyping of the AMD for the ILC | 2924 |
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The Adiabatic Matching Device (AMD), a tapered magnetic field with initial on-axis magnetic field up to 5 Tesla, is required in ILC positron capturing optics. An option of using a pulsed normal conducting structure based on flux concentrator technique can be used to generate high magnetic field*. By choosing the AMD geometry appropriately, one can shape the on-axis magnetic field profile by varying the inner shape of a flux concentrator. In this paper, we present an equivalent circuit model of a pulsed flux concentrator based on frequency domain analysis. The analysis shows a very good agreement with the experiment results from reference*. We have also constructed a prototype flux concentrator based on the circuit model, and experimental results are presented to verify the effectiveness of the model. Using the equivalent circuit model, a flux concentrator based AMD is designed for ILC positron matching. The beam capturing simulation results using the designed AMD are presented in this paper.
* H. Brechna, D. A. Hill and B. M. Bally, "150 KOe Liquid Nitrogen Cooled Flux Concentrator Magnet", Rev. Sci. Instr., 36 1529,1965. |