209358824
THE CHARACTERISTICS OF DIFFERENT MAGNETIC MATERIAL FOR RF CAVITY UNDER PERPENDICULAR MAGNETIZATION
In recent years, a technology of perpendicular magnetization for ferrite loaded cavities is developed. Yttrium Garnet ferrite is generally used for that case with higher frequency range from 30-60 MHz. An attempt is taken to measure the characteristics of different new materials such as FINEMET,METGLAS and NiZn ferrite under the condition of perpendicular magnetization. The results are summarized in this paper.
14603783
A Measurement System Using Gp-Ib For A Magnetic Core Test Cavity
In the design of the RF system of the JHF (Japan Hadron Facilit y) proton synchrotrons, it is very important to find a magnetic core to which satisfies the required condition of the JHF accelerators[1]. Ferrite cores are usually used for the magnetic core of the proton synchrotron, however there are some problems. Generally, some ferrite cores have non-linear characteristics which depend on the RF magnetic field. And, there is a size-dependence of the characteristics. Thus, it is required to measure the characteristics of large size magnetic cores. To measure characteristics of the magnetic cores, we have developed a test cavity which is capable of measuring an actual size one, and measurement system using software ‘HP-VEE’[ 2,3] which is possible to control the measurement devices by using a GP-IB command directly. In this measuring system, the acquisition of data and calculation of the characteristics of the magnetic cores are automatically processed.
55610926
EVALUATION OF MAGNETIC ALLOYS FOR JHF RF CAVITY
A new type of rf accelerating cavity using a high permeability magnetic alloy (MA) has been developed for the high intensity JHF proton synchrotrons. Compared with ordinary ferrites, the MA cores are very stable at high rf magnetic field and thus very high accelerating gradient (=accelerating voltage per cavity length) is available. We have measured several magnetic alloys in order to find a proper material for the cavity. In this paper, the test results are summarized and the evaluation of these materials is presented.
14514129
BEAM LOADING EFFECTS IN JHF SYNCHROTRON
Beam loading effects on the rf system of JHF proton synchrotrons have been investigated by both computer simulation and experiment using a low energy electron beam. From the simulation results, it is found that even under the heavy beam loading the beam acceleration becomes stable if applying the beam loading compensation, and the compensation experiment is succeeded on proto-type Magnetic Alloy loaded cavity.
56351344
RF SYSTEMS FOR JHF SYNCHROTRONS
Based on the measurements of the magnetic cores and R&D works, MA(Magnetic Alloy)-loaded cavity will be adopted for the RF cavity of JHF 50 GeV Main Ring and 3 GeV Booster. Because of high stability at large RF amplitude, high gradient of acceleration voltage (>50 kV/m) is available. By a test cavity, 2.5 kV/core has been already achieved in the CW operation using one MA core of 2.5 cm thickness. For the pulse operation, 5.5 kV/core has been obtained. Another advantage is that the system does not require the tuning system because of the cavity band width is wide enough to cover the RF frequency. A stability analysis shows that the RF system without the tuning loop has wider stable region than high Q cavity system with the loop. A multi-particle simulation shows that the RF system is also stable for the periodic transient and the RF bucket distortion. However, the distortion should be corrected when the Q value of the cavity is low (Q<2).
23554524
A New Design for A Super-Conducting Cavity Input Coupler
An attractive structure using capacitive coupling has been found for the input coupler for the 45 MV/m versions of the International Linear Collider (ILC) project. The coupler supports an electrical field gradient of ∼1 kV/m around the rf window ceramic with 500 kW through power, a VSWR of 1.1 and a frequency bandwidth of 460 MHz. No unwanted resonances were found in the rf window near the first and second harmonics of the operation frequency.
107821728
Characteristics of the results of measurement on 1.3 GHz high gradient superconducting cavities
125432193
State-of-the-art and future prospects in rf superconductivity
55567556
Single crystal niobium development
Tokyo Denkai, KEK and TKX have developed a new niobium ingot slicing technique that allows slicing 150 pieces of large grain niobium discs in two days. Tokyo Denkai installed the slicing machine in December 2009. We inspected the sliced discs by the ultrasonic imaging and understood niobium crystal growth mechanism in Electron Beam Melting, which gave us an idea to make a single crystal niobium ingot. This paper describes the new high-speed production process of niobium discs, an idea of single crystal niobium ingot production and its pilot study result.
116378524
Experience with a zero impedance vacuum flange at He super-leak temperatures for the ILC
A new zero impedance vacuum flange has been developed for the accelerators in the ILC. We choose a unisex type with a 90-degree sharp edge forming the vacuum seal and giving a continuous smooth connection providing zero impedance as seen from the bunched beam and rf power. The variation in flatness between the flange and gasket along the inside wall is less than 50-μm. An He super-fluid leak rate of below 10 [atm/cm3/sec] was measured using the "build up method", i.e. the test measured the pressure built up over a three hour period while held at below 2-oK. We tested the several potential gasket materials: OFC (Oxygen Free Copper) alone, Nb (niobium) plated with 10-μm of OFC, and bulk Nb, all at temperatures below 2-oK. The same unisex type flange has also been used for the input power coupler for coaxial waveguide and for a cold side demountable type rf window. A long test run was carried out at an rf power of 1-MW, and a 1.5-msec pulse width, 5-pps repetition rate. Further, suitability was confirmed by operation at a maximum power of up to 2-MW, and a 1.5-msec pulse width, 3-pps repetition rate for 6 hours.