02 The recent results of the ATF

This report describes the recent results of the beam commissioning of the ATF at KEK. Recent progress on the studies on production of low emittance beam, multi-bunch beam operation and development on beam instrumentation are discussed. So far, a horizontal emittance of 1.7 ± 0.3 nm was measured with wire-scanners in the extraction line and with the horizontal spatial coherence using an SR interferometer. In addition, a vertical emittance of 15 ± 7.5 pm was measured with a laser wire and the SR interferometer in the ring and 5 wire scanners.

High density mapping systems for SRF cavities

20th International Conference on RF Superconductivity (SRF 2021)In order to evaluate the performance of a superconducting cavity, we are developing a mapping system to measure the distribution of cavity temperature, field emission X-rays, and trapped magnetic flux with high positional resolution. In order to construct a system with high positional resolution, a large number of sensors are required. However, as the number of sensors increases, so does the amount of wiring, which increases the complexity of the wiring in the cryogenic apparatus, and also increases the heat transfer through the wiring, which disturb efficient operation of cavity tests. We are developing an efficient mapping system with a multiplexer that scans the readout signal on the same circuit as the sensor in the cryogenic dewar where the cavity test is conducted. In this presentation, we report the outline and test results of the mapping system under developmen

A Survey of Pressure Vessel Code Compliance for Superconducting RF Cryomodules

Superconducting radio frequency (SRF) cavities made from niobium and cooled with liquid helium are becoming key components of many particle accelerators. The helium vessels surrounding the RF cavities, portions of the niobium cavities themselves, and also possibly the vacuum vessels containing these assemblies, generally fall under the scope of local and national pressure vessel codes. In the U.S., Department of Energy rules require national laboratories to follow national consensus pressure vessel standards or to show "a level of safety greater than or equal to" that of the applicable standard. Thus, while used for its superconducting properties, niobium ends up being treated as a low-temperature pressure vessel material. Niobium material is not a code listed material and therefore requires the designer to understand the mechanical properties for material used in each pressure vessel fabrication; compliance with pressure vessel codes therefore becomes a problem. This report summarizes the approaches that various institutions have taken in order to bring superconducting RF cryomodules into compliance with pressure vessel codes.Comment: 7 p

STATUS OF SUPERCONDUCTING RF TEST FACILITY(STF)

Abstract The superconducting RF test facility (STF) in KEK is aiming to promote R&D of superconducting linear accelerator to be used in the International Linear Collider (ILC). The STF construction is planned to sub-divided to two parts. They are phase-1 plan and phase-2 plan. The phase-1 plan is aiming to have quick experience on all aspect of 1.3GHz SC cavity and cryomodule technologies by producing 4 TESLA-shape cavities with 5m cryostat and 4 LL-shape cavities with another 5m cryostat, which are powered by 5MW klystron. The other aspect of phase-1 development is to construct new cavity surface treatment facilities, such as electro-chemical polishing and clean room to get stable high gradient performance. The developments of the phase-1 are almost completed in 2008. The results and the developed technology are introduced in this paper

STATUS OF SUPERCONDUCTING RF TEST FACILITY (STF)

Abstract The superconducting RF test facility (STF) in KEK is the facility to promote R&D of the International Linear Collider (ILC) cavities and cryomodule. The surface treatment and field test of 9-cell cavities are performed in daily bases. The second electro-chemical polishing facility was completed its construction, and became operational. As an international project; S1-Global cryomodule test is now conducted at STF. The cool down experiment and RF performance test are under execution towards end of December 2010. In parallel, modification of STF phase-2 plan was discussed and the plan was changed. In order to accommodate efficient R&D and effective accelerator demonstration with limited budget, the new RF powering scheme; DRFS (Distributed RF System) was adopted. All of the STF development and modified plan done in 2009-2010 are summarized in this paper