We discuss a new circuit theory of multi-conductor transmission lines. According to the theorem, a symmetrical three-line (S3L) circuit gives an excellent noise reduction compared with a nominal two-line circuit. The practice of this S3L circuit was proposed by the author for power supplies of the twin synchrotrons of HIMAC (Heavy Ion Medical Accelerator in Chiba) 20 years ago, and the theory has recently been established by Prof. Hiroshi Toki, who has found a new principle of circuit theory based on the retarded potential and coefficients of potential. This theory provides a clear mathematical definition of common-, normal-, and antenna-modes for electromagnetic phenomena with a set of coupled integro-differential equations among three modes. A signal contamination by noise is understood as coupling among these three modes. A relation between the “noise and signal”, and the three modes is generally complicated, however, such a relation is simplified very much in the case of the S3L circuit. The normal mode is decoupled from the common- and antenna-modes, so that a pure signal is obtained without any contamination of noise with a common-mode filter. This article describes the essence of both the practice and theory of the method in three parts; “Part 1 Outline”, “Part 2 Practice”, and “Part 3 Theory”.

Klystron failure analysis, emission control, phase variation and maintenance are described in this last paper of three successive series. Four main failure causes extracted from SLAC data of SLAC 1965-1982, and KEK data are explained in detail. Regarding to Klystron life, KEKs dip test which is a quick way to examine the emission is explained. The phase variation should be small for accelerator and good stability on applied voltage and cooling water temperature are essential. Klystron maintenance which is important for the effective use is explained.

We had been constructing a new facility for the fabrication of superconducting RF cavity at KEK from 2009 to 2011. In the facility, we have installed a deep-drawing machine, a half-cup trimming machine, an electron-beam welding machine, and a chemical etching room in one place. We started the studies on the fabrication of 9-cell cavity for International Linear Collider (ILC) using this facility. The studies are focusing on the cost reduction with keeping high performance of cavity, and the goal is the establishment of mass-production procedure for ILC. We already finished the fabrication of two 9-cell cavities in this facility. This article reports the current status of the studies.