200MHz superconducting RF cavity development for RLAs 1 (2008)
R. L. Geng, H. Padamsee, D. Hartill, P. Barnes, J. Sears, R. Losito, ...
Abstract. A 200MHz single-cell superconducting Nb-Cu cavity has been fabricated and tested at 4.2 K and at 2.5 K. The low field Q0 reached 1:5 10 10 at 4.2 K. The accelerating gradient (Eacc) reached...
PROGRESS OF 2-CELL CAVITY FABRICATION FOR (2008)
Cornell Erl Injector, R. L. Geng, P. Barnes, M. Liepe, V. Medjidzade, H. Padamsee, ...
absorbers are fitted between cavities to damp HOM’s. A sketch layout of the five injector cavities, symmetric twin input couplers, and HOM absorbers is shown in Fig. 1. Five 1300 MHz...
C. E. Chen, R. L. Geng, J. H. Song, L. F. Wang, J. Yu, B. C. Zhang, ...
A laser-driven photo-cathode electron gun capable of producing pulsed electron beams of 100 KeV with a duration of 35 ps was constructed as a continuing effort towards a high-brightness...
Mirco-Structures of RF Surfaces in the Electron-Beam-Weld Regions of Niobium (2007)
R.L. Geng, J. Knobloch, H. Padamsee
Micro-structures of RF surfaces in the electron-beam-weld (EBW) regions of niobium samples were studied. These surfaces were polished with different techniques, namely buffered chemical polish (1:1:2...
Abstract MULTIPACTING IN A RECTANGULAR WAVEGUIDE (2007)
R. L. Geng, H. Padamsee, V. Shemelin
Multipacting in the reduced-height waveguide coupler used in CESR III superconducting RF system is studied through numerical and simplified analytical calculations. An improved model for secondary...
Abstract THERMAL ANALYSIS OF A 200MHZ NB-CU CAVITY (2007)
The expected Q(Eacc) curves are calculated for a 200 MHz Nb-Cu cavity. An exponent-law formalism for BCS resistance is introduced to account for the Q-drop as a function of Eacc. Pipe-cooling of the...
On the Low-Field Q-Slope of RF Superconducting Niobium Cavities Cooled by Helium-I (2007)
Experimental measurements have consistently shown that RF superconducting Niobium cavities cooled by HeI exhibit a mild Q-slope starting at very low gradients. This Q-slope has been attributed to a...
Dynamical aspects of multipacting induced discharge in a rectangular waveguide. (2005)
Geng, R. L., Goudket, P., Carter, Richard G., Belomestnykh, S., Padamsee, H., Dykes, D. M.
Multipacting induced discharge in a rectangular waveguide is studied experimentally at a RF frequency of 500 MHz. The waveguide has a cross-section of 457 mm by 102 mm. The maximum forward RF power...
Abstract WORLD RECORD ACCELERATING GRADIENT ACHIEVED IN A SUPERCONDUCTING NIOBIUM RF CAVITY (2004)
R. L. Geng, H. Padamsee, A. Seaman, V. D. Shemelin, At Mv/m To
46 MV/m was achieved in a superconducting niobium cav-ity with an unloaded quality (¢¤ £ factor) ¥§¦¨¥�©�� over at a temperature of � 1.9 K. In pulsed mode, 47 MV/m was achieved....
Suppression of multipacting in rectangular coupler waveguides. (2003)
Geng, R. L., Padamsee, H., Belomestnykh, S., Goudket, P., Dykes, D. M., Carter, Richard G.
Although a rectangular waveguide coupler has the conceptual advantages of simplicity and capability of withstanding higher power, builders of modern superconducting accelerators are routinely...
Suppression of multipacting in rectangular coupler waveguides (2003)
Geng, R L, Padamsee, H, Belomestnykh, S, Goudket, P, Dykes, D M, Carter, R G
A 1500 Mhz Niobium Cavity Made of Electropolished Half-Cells (2003)
R. L. Geng, A. Crawford, G. Eremeev, H. Padamsee, J. Sears
A 1500 MHz niobium cavity has been fabricated with two half-cells, which are pre-electropolished with a very simple and compact system. In this paper, we present halfcell electropolishing, cavity...
Experimental studies of electron multipacting in CESR type rectangular waveguide couplers. (2002)
Geng, R. L., Belomestnykh, S., Padamsee, H., Reilly, J., Goudket, P., Dykes, D. M., ...
Multipacting induced breakdown in rectangular waveguide couplers. (2002)
Geng, R. L., Belomestnykh, S., Padamsee, H., Reilly, J., Goudket, P., Dykes, D. M., ...
Condensed/adsorbed gases can enhance field emission in superconducting cavities and deteriorate the input coupler performance in a superconducting RF system. It is therefore important to understand...
Exploring Multipacting Characteristics of a Rectangular Waveguide (1999)
Multipacting (MP) characteristics of the rectangular waveguide used for CESR-III Superconducting RF (SRF) system were investigated by using a newly developed 3-D computer code. MP bands were...