1. First Experiments at the Yale Ka-band Test Facility* M.A. LaPointe, 1 Y. Jiang, 1 S.V. Shchelkunov, 1 V.P. Yakovlev, 2,3 S.Yu. Kazakov, 2,4 J.L. Hirshfield, 1,2 A.L. Vikharev, 2,5 A.A. Vikharev, 2,5 O.A. Ivanov, 2,5 A. Gorbachev, 2,5 M. Lobaev 2,5 1 Yale University, New Haven CT, 2 Omega-P, Inc., New Haven CT 3 FNAL, Batavia IL, 4 KEK, Tsukuba, Japan, 5 IAP, Nizny Novgorod, Russia *Sponsored by US Department of Energy, Office of High Energy Physics Advanced Accelerator Concepts Workshop Santa Cruz, CA 27July - 2 August 2008 ÎUniversityOmega-P, Inc.

2. Outline Status of Facility Initial Experiments * Quasi Optical Active Pulse Compressor * RF Breakdown Cavity for material and alloy testing Waiting Experiments * Pulsed Heating Cavity * Diamond Breakdown Cavity Planned Experiments * Hidden Sector Physics * ? Advanced Accelerator Concepts Workshop Santa Cruz, CA 27July - 2 August 2008 ÎUniversityOmega-P, Inc.

3. Status of Facility Advanced Accelerator Concepts Workshop Santa Cruz, CA 27July - 2 August 2008 ÎUniversityOmega-P, Inc.  The Yale Ka-band Test Facility began operation as a user facility 1 Sep, 2007.  Initial tests of a Quasi-optical pulse compressor and a cavity for breakdown studies have begun.

4. Status of Facility Advanced Accelerator Concepts Workshop Santa Cruz, CA 27July - 2 August 2008 ÎUniversityOmega-P, Inc.  During initial experiments no resonance was observed in 34 GHz QO pulse compressor.  An unanticipated mode was discovered which operated at 31.9 GHz.  Mode is dependent on the circuit outside of output cavity.  Magnicon parameters were found which do not excite this mode.  Interferometer system was set up to monitor the magnicon frequency

5. Status of Facility Advanced Accelerator Concepts Workshop Santa Cruz, CA 27July - 2 August 2008 ÎUniversityOmega-P, Inc.  A Cryomech helium reliquefier has been ordered and is due to arrive early August.  The unit will provide 6 l/day of LHe recycling which is about the loss rate while operating the SC magnet.  Any net loss can be made up by gaseous helium which then is liquefied.  This will allow the facility to run year round without having to partially shut down due to helium costs.

6. Initial Experiments: Quasi Optical Active Pulse Compressor A.L. Vikharev, A.A. Vikharev, O.A. Ivanov, A. Gorbachev, M. Lobaev Advanced Accelerator Concepts Workshop Santa Cruz, CA 27July - 2 August 2008 ÎUniversityOmega-P, Inc. After attempts at passive compression with both copper and active gratings were unsuccessful it was discovered that the magnicon was operating in an unanticipated (parametric?) mode at 31.9 GHz. An initial operating regime was found for the magnicon which gave the proper third harmonic output at 34.3 GHz, albeit at low power (~250 kW/arm).

7. Initial Experiments: Quasi Optical Active Pulse Compressor Advanced Accelerator Concepts Workshop Santa Cruz, CA 27July - 2 August 2008 ÎUniversityOmega-P, Inc. After magnicon operation was in proper mode, the resonance in the QO active pulse compressor was seen. The next set of experiments which will include the use of the active grating is scheduled for October

8. RF Breakdown Cavity Advanced Accelerator Concepts Workshop Santa Cruz, CA 27July - 2 August 2008 ÎUniversityOmega-P, Inc.  This device to measure surface breakdown on specially prepared pins is currently installed.  The device consists of a TM 030 cavity with two axial pin protrusions.  The pins are to be made from various metals and alloys to test their relative breakdown properties.  The electric field is designed to be maximum on the surface of the protrusions.  Initial breakdown (conditioning?) events were observed with ~200 kW of incident power corresponding to ~ 20 MV/m electric fields.

9. RF Breakdown Cavity Advanced Accelerator Concepts Workshop Santa Cruz, CA 27July - 2 August 2008 ÎUniversityOmega-P, Inc.  The cavity is tuned by either adjusting the pin spacing in the cavity or the temperature of the cavity.  Efforts are made to make the pins symmetric in the cavity.  After adjusting the pins to be symmetric, the temperature of the cavity is adjusted to retune the resonance as indicated in the graph.

10. Pulsed Heating Cavity Advanced Accelerator Concepts Workshop Santa Cruz, CA 27July - 2 August 2008 ÎUniversityOmega-P, Inc. The TE 011 test cavity schematic layout and the RF magnetic field pattern are shown in the figure below. The protrusion peak magnetic field intensity is 3x larger than the next highest field point. The geometry, including input coupler, is axisymmetric to minimize surface electric fields.

11. Diamond Breakdown Cavity S.Yu. Kazakov. V.P. Yakovlev, A.L. Vikharev, et al Advanced Accelerator Concepts Workshop Santa Cruz, CA 27July - 2 August 2008 ÎUniversityOmega-P, Inc. Diamond test cavity (H 02 mode) is built and in house awaiting installation. Cavity is designed to test surface and volume breakdown limits for CVD diamond. Tests will include hydrogenated and de-hydrogenated diamond samples First tests scheduled for Oct/Nov ‘08

12. Hidden Sector Physics O.K. Baker, P.L. Slocum, Yale University Advanced Accelerator Concepts Workshop Santa Cruz, CA 27July - 2 August 2008 ÎUniversityOmega-P, Inc. An experiment is being designed to look for hidden sector photons (HSPs), a gauge boson interacting with matter via gravity like interactions. The masses of these HSPs are expected in the sub-eV range (30 GHz ~ 100  eV). The experiment consists of two high Q cavities in up to a 7 Tesla magnetic field. The expected photon yield is given by the estimate

13. Further Collaborations Welcomed Advanced Accelerator Concepts Workshop Santa Cruz, CA 27July - 2 August 2008 ÎUniversityOmega-P, Inc. There have been a few additional inquiries into using the Yale Ka-band Test Facility Your Experiment Here