Design of the radio frequency section of a multiple beam klystron working in the J-band frequency range
The multiple beam klystrons (MBK) offer some distinct advantages over their single beam versions including higher average power, relatively lower operating voltages, higher bandwidth and low individual beam current. In this paper the design of the radio frequency (RF) section of a multiple beam klystron working in the J band frequency range is presented. The RF design and simulation has been carried out using a commercially available three dimensional electromagnetic design code. A cold test model of the RF cavity has been fabricated and its resonant frequency has been characterized. Design of the individual cavities, simulation results of the beam wave interaction as well as the frequency characterization of the fabricated cavity is presented in this paper.
Multiple-beam klystron amplifiers: performance parameters and development trends
This paper presents a description of multiple-beam klystrons (MBKs). The main material is based on experimental results and practical experience gained at the Federal State Unitary Enterprise Research and Production Corporation "Istok," where MBK technology has been extensively developed and manufactured beginning in the 1960s. In addition to this material, some original ideas, designs, and experimental data from other enterprises are presented. Three classes of MBKs are discussed in detail: high-power, medium-power, and miniaturized devices. Features common to all MBK classes as well as the reasons constraining MBK parameters in comparison with the parameters of single-beam klystrons are also discussed. The principal characteristics of typical MBKs are presented and main application areas for different MBK types are considered. Finally, directions for further development of this branch of microwave amplifiers are discussed.
Semiautomated quantification of the fibrous tissue response to complex three-dimensional filamentous scaffolds using digital image analysis.
Fibrosis represents a relevant response to the implantation of biomaterials, which occurs not only at the tissue-material interface (fibrotic encapsulation) but also within the void fraction of complex three-dimensional (3D) biomaterial constructions (fibrotic ingrowth). Usual evaluation of the biocompatibility mostly depicts fibrosis at the interface of the biomaterial using semiquantitative scores. Here, the relations between encapsulation and infiltrating fibrotic growth are poorly represented. Virtual pathology and digital image analysis provide new strategies to assess fibrosis in a more differentiated way. In this study, we adopted a method previously used to quantify fibrosis in visceral organs to the quantification of fibrosis to 3D biomaterials. In a proof-of-concept study, we transferred the "Collagen Proportionate Area" (CPA) analysis from hepatology to the field of biomaterials. As one task of an experimental animal study, we used CPA analysis to quantify the fibrotic ingrowth into a filamentous scaffold after subcutaneous implantation. We were able to demonstrate that the application of the CPA analysis is well suited as an additional fibrosis evaluation strategy for new biomaterial constructions. The CPA method can contribute to a better understanding of the fibrotic interactions between 3D scaffolds and the host tissue responses.