High-Power High-Efficiency L-band Multiple-Beam Klystron Development at CPI
Communications and Power Industries, Inc., has designed and manufactured two versions of a 10-MW-peak high-efficiency multiple-beam klystron (MBK) operating at 1300 MHz. This type of klystron is favored for large particle accelerator projects such as the European X-ray Free-Electron Laser at the Deutsches Elektronen Synchrotron (DESY). Two klystrons have been made for DESY. The first-generation MBK was a vertically oriented prototype using a six-cavity design with higher order mode input and output cavities and conventional intermediate cavities. For cost and performance reasons, the second-generation MBK, designated VKL-8301B, utilized seven coaxial fundamental-mode cavities and is an “industrialized” horizontally oriented klystron. The klystron was designed and optimized using state-of-the-art multidimensional design codes to ensure that all performance requirements are exceeded. Agreement between the simulated and measured performances is good. The VKL-8301B prototype achieved a peak saturated RF output power of 10.4 MW and 67.8% efficiency. The data were measured at the full 1.5% duty and with 1.5-ms pulse width. The klystron satisfied all required operating conditions, including stable operation into an output mismatch of 1.2:1 voltage standing wave ratio at various phases. The prototype has been shipped to DESY and has been successfully tested by a customer.
Design of the RF Circuit for a Coaxial Cavity High-Power Multiple-Beam Klystron
This paper presents the design methodology and detailed design of the interaction circuit for use in an L-band 10-MW MBK, which operating in the fundamental mode at a center frequency of 1.3 GHz. Coaxial cavities are adopted to give adequate space for the use of multiple large cathodes, which has a low cathode loading and thereby facilitate a long lifetime. The emphasis for the present design is on efficiency and high-peak output power. The initial design was carried out using the large signal code KLY. To calculate the beam-wave interaction characters conveniently with cavities present, we developed a 2-D single-beam equivalent design methodology, in which the multitunnel coaxial cavities are replaced by the conventional single-tunnel cylindrical cavities with transformed RF parameters. The 3-D PIC simulations with actual coaxial cavity geometries are carried out at last to check on the large signal and the 2-D PIC simulations. The 3-D simulation results indicate that the equivalent design methodology is effective. The final RF circuit consists of six coaxial cavities including a second-harmonic cavity to reduce the device length. The circuit has a predicted gain of 50 dB at a peak pulsed output power of 10.4 MW with a corresponding electronic efficiency of more than 68%. The design and test results of the output system with two windows are also presented.
Use of a specific antiserum for renin detection in human kidney.
The use of anti-human renin antibodies made possible the intrarenal localization of renin in human kidney by immunofluorescence. In normal kidney, only some juxtaglomerular apparatus (JGA) were fluorescent. In these JGA, granular or diffuse fluorescence was only seen in afferent arterioles and was not present in all cells. In the ischemic areas of partially infarcted kidney, fluorescence was seen in all JGA and in interlobular arteries. In these arteries the most eccentric cells were often the most positive. In the nonischemic areas of the same kidneys, fluorescence was not seen in JGA, but was observed in proximal tubular cells, suggesting the reabsorption of filtered renin at this site.