Masako Iwasaki

Design and Construction of the SuperKEKB QC1 Final Focus Superconducting Magnets

The construction of SuperKEKB, which consists of 7 GeV electron and 4 GeV positron main rings, is now going on. The final focus superconducting quadrupole magnets in the interaction region have been designed and constructed. From the field qualities of the prototype magnets, the magnet designs were modified, and the manufacturing and assembling methods of the coils were changed to satisfy the design values. The field measurements of the magnets were performed at room temperature, and confirmed that they were acceptable for the beam operation. In the paper, the design and the construction of the final focus quadrupole magnets, QC1, which will be located at the closest position to the beam interaction point, are presented.

Fabrication and Testing of a Model Quadrupole Magnet for Linear Accelerators

A model of a quadrupole magnet for linear accelerators was designed, fabricated, and tested at KEK in order to gain fabrication experience and a better understanding of superconducting magnet characteristics. The assembly has a design field gradient of 56.5 T/m, an aperture of 92 mm, and a cold mass length of 680 mm. Furthermore, it is designed as a superferric magnet with four racetrack coils wound with a specially fabricated ribbon cable of eight superconducting strands. In this paper, we present details of the magnet design, fabrication, and the results of its cold tests. Data of the field measurements are also presented in brief.

Compact 8-lead unit for the SC correction coils of the SuperKEKB IR magnet system

In the proposed SuperKEKB interaction region (IR) magnet system 40superconducting (SC) correction coils are designed to perform some specific functions withcurrent of about 50 A. To energize these coils, 80 current leads will be mounted in thecryostats where the stringent spatial constraint and the cryogenic operation require acompact and optimum design. We propose a compact unit to integrate 8 helium vaporcooled leads (4 pairs). The 8 leads are made of brass and consist of two structures for thetransported current and helium vapor, which are designed and simulated by finite elementmodel (FEM). This paper will introduce the material selection and structure details. To equalize the temperature profiles of the individual leads under the different currents and helium flows, some copper blocks are placed between leads. In the cold test, the 8 leadswere operated in the nominal mode and responded safely to some transient situation. This paper will present the thermal and electrical comparison between the experi...

Design and Construction of the Final Focus Quadrupole R&D Magnet for Super-KEKB

For upgrading the electron-positron collider KEKB, the final focusing magnet system in the beam interaction region has been studied. The designed magnet system consists of five superconducting and three permanent quadrupole magnets. A superconducting quadrupole magnet has been constructed as the R&D of this system. In this paper, design and construction of this R&D magnet are reported.

Analysis of the Performance of a Model Quadrupole Magnet for a Linear Accelerator

A model quadrupole magnet for a future linear accelerator has been designed, fabricated, and tested at KEK. The model quadrupole is a superferric superconducting magnet with a design field gradient of 57 T/m. The design field gradient is obtained by saturating the iron yoke. Superferric magnets are considered to have the advantage of simplicity, less sensitivity to the position of the superconductor coils, and are therefore thought to be easier to construct and less expensive than usual superconducting magnets. However, if the iron is heavily saturated, the magnetic field becomes more sensitive to the coil positions. The magnetic properties of the magnet were measured with a harmonic coil, and its field gradient, effective length, and multipole components were compared with a 3D simulation. The results are presented and discussed in this paper.

Design and Construction of the QC2 Superconducting Magnets in the SuperKEKB IR

The first stage commissioning of SuperKEKB is going on without the final focus system from Feb. 2016. The final focus system, which consists of 55 superconducting magnets, is still in the construction stage. The 8 main superconducting quadrupole magnets are designed to consist of quadrupole doublets as QC1 and QC2 for each beam line. All of the quadrupole magnets were constructed. In this paper, the design and the construction of the quadrupole magnets, QC2, are presented. INTRODUCTION SuperKEKB with a target luminosity of 8×10, which is 40 times higher than KEKB [1], is now being operated without the final focus system from February 2016 as the Phase-1 commissioning [2]. The accelerator design is based on the Nano Beam Scheme [3] with a large horizontal crossing angle of 83 mrad between the electron (e-) and positron (e+) beams and the beam sizes of about 50 nm at the interaction point (IP), where the beam energies of eand e+ are 7 GeV and 4 GeV, respectively. The final focus system [4] was designed with 55 superconducting magnets of 8 main quadrupoles, 4 compensation solenoids and 43 correctors [5]. Final beam focusing is obtained with quadrupole doublets of the main quadrupoles, QC1 and QC2, for each beam. For the e+ beam line, QC2LP and QC2RP were constructed for the left and right hand side to IP, respectively, and for the ebeam line, QC2LE and QC2RE were constructed. These superconducting magnets are assembled into two cryostats, and they are installed inside of the particle detector, Belle II [6]. Therefore, the final focusing system is operated under the magnetic field of 1.5 T by the Belle solenoid. For reducing the influence of this solenoid field on the beam collision, the compensation solenoids, which generate the solenoid fields of the opposite field direction, are installed into the cryostats. QC2LP and QC2RP are assembled inside of the compensation solenoid bores. QC2LE and QC2RE are assembled out of the solenoids. The QC1 magnets were already reported in the reference [7]. In this paper, the design and the construction of the QC2 magnets are reported.

The Construction of the SuperKEKB Magnet Control System

There were more than 2500 magnet power supplies for KEKB storage rings and injection beam transport lines. For the remote control of such a large number of power supplies, we have developed the Power Supply Interface Controller Module (PSICM), which is plugged into each power supply. It has a microprocessor, ARCNET interface, trigger signal input interface, and parallel interface to the power supply. The PSICM is not only an interface card but also controls synchronous operation of the multiple power supplies with an arbitrary tracking curve. For SuperKEKB we have developed the upgraded version of the PSICM. It has the fully backward compatible interface to the power supply. The enhanced features includes high speed ARCNET communication and redundant trigger signals. Towards the phase 1 commissioning of SuperKEKB, the construction of the magnet control system is ongoing. First mass production of 1000 PSICMs has been completed and their installation is in progress. The construction status of the magnet control system is presented in this report. (1) Introduction ----Original PSICM KEKB, the asymmetric electron-positron collider for B-meson physics, started in operation in Dec.1998 and finished in Jun. 2010. KEKB control system was EPICS-based, using more than 100 VME/VxWorks computers as IOC (I/O Controller). About 2500 magnet power supplies were installed in the KEKB storage rings and the injection beam transport lines and controlled by 11 IOCs. To connect such many power supplies to the IOCs, we adopted ARCNET as the field bus and developed the PSICM (Power Supply Interface Controller Module). . Original PSICM New PSICM Microprocessor AM186 MPC8306 Clock frequency 20MHz 133MHz Data memory 256kB SRAM 128MB DDR2 SDRAM Program memory 256kB EPROM 64MBit NOR FLASH ARCNET interface 2.5Mbps Backplane mode 2.5Mbps/5Mbps/10Mbps Backplane mode Controller COM20020 COM20022 Media driver HYC2485 HYC5000 Power required 5V 0.4A 5V 1A ARCNET Interface board (4 ch. / boards)

Pulse-to-Pulse Modulation of Injector Linac with Event Timing System

The Pulse-to-Pulse Modulation of Injector Linac at KEK is developed for efficient injections. It automatically switches the beam mode with the real-time process. We integrated this system in 2009 to simultaneously perform the top-up filling into more than one rings with only one injector. The system is based on the Event Timing System. Recently, we upgraded the configuration of Event Timing System to satisfy the complicated requirements of SuperKEKB and developed the test procedure to understand stability of real-time process. The failure of real-time process at Main Trigger Station is intentionally caused when we shorten the allowed computing time as the stress test. The reasonable dependence between the failure rate and the allowed computing time is determined. It indicates we can evaluate the failure rate in case of normal operation at Main Trigger Station.

Development of the Superconducting Quadrupole Magnet for the SuperKEKB Final Focusing System

We have developed the superconducting final-focus quadrupoles for SuperKEKB, the next generation B-factory experiment in Japan. The system consists of four quadrupole doublets for incoming and outgoing electron and positron beams, respectively. A R&D superconducting quadrupole magnet was fabricated. In this paper, we describe the results on the excitation test and the magnetic field measurements of this R&D magnet.