| Paper | Title | Page |
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| MOPAS069 | Analysis of a Compact Circular TE 01-Rectangular TE 02 Waveguide Mode Converter | 587 |
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An analysis method for a three section mode transformer that converts a TE 01 circular waveguide mode to a TE 02 rectangular waveguide mode will be presented. Experimental results for this taper were earlier published in*. The middle section is a cylinder with a wall radius defined by rw = a(1 + d cos(2Θ)), where a is the radius of the circular guide and d is a design parameter. This cylinder is connected on either side to a circular waveguide and a rectangular waveguide section respectively, through tapered waveguide sections. In this analysis we used a perturbation technique where the rectangular waveguide section's wall radius is treated as a Fourier series expansion with a, the fundamental radius and d the perturbation parameter. By applying the proper boundary conditions we optimize the taper dimensions to minimize conversion into spurious modes.
*S. G. Tantawi et al., Physical Review Special Topics – Accelerator and Beams. 8, 042002 (2005) |
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| WEPMS018 | Superconducting Materials Testing with a High-Q Copper RF Cavity | 2370 |
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| Magnesium diboride (MgB2) has a transition temperature (Tc) of ~40 K, i.e., about 4 times higher than niobium (Nb) that has been used for recent accelerators. The studies in the last 3 years have shown that it could have about one order of magnitude less RF surface resistance (Rs) than Nb and much less power dependence compared to high-Tc materials such as YBCO up to ~400 Oe. The tests to check the RF critical magnetic field, an important parameter to determine the feasibility for accelerator application, are underway. We are planning to test different thickness films and with different coating methods. This paper describes the results obtained so far. One of the objectives is to verify Gurevich's theory of getting higher critical field than Nb by adding a very thin layer (less than penetration depth) to Nb. In addition, some CW tests on power dependence up to higher magnetic fields are planned and some results will be shown if available at the time of conference. | ||
| WEPMS039 | High Power Tests of Normal Conducting Single-Cell Structures | 2430 |
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Funding: This work was supported by the U. S. Department of Energy contract DE-AC02-76SF00515.
We report results of the first high power tests of single-cell traveling-wave and standing-wave accelerating structures. These tests are part of an experimental and theoretical study of RF breakdown in normal conducting structures at 11.4 GHz*. The goal of this study is to determine the gradient potential of normal conducting, RF powered particle beam accelerators. The test setup consists of reusable mode converters and short test structures powered by SLAC?s XL-4 klystron. This setup was created for economic testing of different cell geometries, cell materials and preparation techniques with short turn-around time. The mode launchers and structures were manufactured at SLAC and KEK and tested in the klystron test laboratory at SLAC.
* V. A. Dolgashev et al., "RF Breakdown In Normal Conducting Single-Cell Structures," SLAC-PUB-11707, Particle Accelerator Conference (PAC 05), Knoxville, Tennessee, 16-20 May 2005, pp. 595- 599. |
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| WEPMS040 | Active RF Pulse Compression Using Electrically Controlled Semiconductor Switches | 2433 |
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| In this paper, we will present our recent results on the research of the ultrafast high power RF switches based on silicon. We have developed a switch module at X-band which can use a silicon window as the switch, and scaled it to 30GHz for the CLIC application. The switching is realized by generation of carriers in the bulk silicon. The carriers can be generated electrically or/and optically. The electrically controlled switches use PIN diodes to inject carrier. We have built the PIN diode switches at X-band, with <300ns switching time. The optically controlled switches use powerful laser to excite carriers. By combining the laser excitation and electrical carrier generation, significant reduction in the required power of both the laser and the electrical driver is expected. High power test is under going. | ||
| THPMS075 | High Power Testing of a Fused Quartz-based Dielectric-loaded Accelerating Structure | 3157 |
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| We report on the most recent results from a series of high power tests being carried out on RF-driven dielectric-loaded accelerating (DLA) structures. The purpose of these tests is to determine the viability of the DLA as a traveling-wave accelerator and is a collaborative effort between Argonne National Laboratory (ANL), Naval Research Laboratory (NRL), and Stanford Linear Accelerator Center (SLAC). In this paper, we report on the recent high power tests of a fused quartz-based DLA structure that was carried out at incident powers of up to 12 MW at NRL and 37 MW at SLAC. We report experimental details of the RF conditioning process and make comparison of our multipactor model to the experiment, including tests of geometrical scaling laws and the time evolution of multipactor. Finally, we discuss future plans for the program including a planned test of new quartz-based DLA with a different geometry to both reach higher accelerating gradients and to continue the parametric study of multipactor. | ||
| THPMS096 | Development of a Dielectric-Loaded Test Accelerator | 3211 |
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Funding: Work supported by DoE and ONR.
A joint project is underway by the Naval Research Laboratory (NRL) and Argonne National Laboratory (ANL), in collaboration with the Stanford Linear Accelerator Center (SLAC), to develop a compact X-band accelerator for testing dielectric-loaded accelerator (DLA) structures.* The accelerator will use a 5-MeV injector previously developed by the Tsinghua University in Beijing, China, and will accommodate test structures up to 0.5 m in length. Both the injector and the structures will be powered by an 11.4-GHz magnicon amplifier that can produce 25 MW, 200-ns output pulses at up to 10 Hz. The injector will require ~5 MW of rf power, leaving ~20 MW to power the test structures. This paper will present a progress report on the construction and commissioning of the test accelerator, which will be located in a concrete bunker in the Magnicon Facility at NRL.
* S. H. Gold et al., Proc. PAC 2005. |