Dr. Kaoru YOKOYA (KEK, Japan)
Dr. Tripti Sekhar DATTA (IUAC, India)
Although superconductivity was discovered in 1911, but its application for major accelerator programme was realized only during 1975-1980 at Fermi National Accelerator Laboratory through the Tevatron Accelerator. With similar concept, Large Hadron Collider (LHC) was commissioned recently with a total circumference of 27 km. and by using superconducting quadrupole and dipole magnet with a field of 8.3 Tesla and operating at 1.9 K. Particle accelerators capable of producing very high accelerating fields and with energies in TEV range have been made possible by use of superconducting magnets and RF cavities. Size of accelerator is reduced because of high field (5- 10 Tesla) and the power consumption is reduced because of low surface resistance in superconductors. In Asia, prior to 1990 the accelerator with cryogenics and superconductivity was limited to Japan for their project on TRISTAN/ KEK-B collider at KEK and superconducting cyclotron at RIKEN. Superconducting activities are being pursued in all over Asia on many mega projects along with the proposed International Linear Collider (ILC). Along with the development of practical superconductor, significant progress is visible on optimization of helium liquefaction cycle that improves the inverse Coefficient of Performance (COP) from 1000 W to 225 W for one Watt of refrigeration at 4.2 K. Improvement of surface preparation technique of RF cavity to have an average accelerating field of 31.5 MV/m and reduction of plug power consumption of 500 W to generate 1 W refrigeration at 2 K made it possible to take a challenging project like International Linear Collider (ILC) with electron energy of 500 to 1000 GeV. Present talk will be highlighting the role of cryogenics and superconductivity for various accelerator programme in Asia.
Dr. Tripti Sekhar DATTA (IUAC, India)
This lecture will give an introduction on superconductivity prior to the course lecture on superconducting magnet, cavity and cryogenics. It starts with the definition of superconductor, the critical properties of Tc, JC, Hc and its relation with temperature. The Meissner effect with perfect diamagnetism of superconductor will be discussed. Other thermodynamic properties related to the difference between Type 1 and Type II superconductor and their application in will be discussed. History of superconducting materials, that includes High Temperature Superconductor (HTS) and its use by using a cryocooler will be touched. This lecture will also give a brief introduction on cryogenics, definition on cryogenics and the boundary with respect to temperature along with the reason. It will also cover the properties of cryogenic fluid including critical point and Triple point and its significance with respect to cooling and heat transfer. It will briefly touch on application of cryogenics and superconductivity other than the accelerator programme.
Prof. Toru OGITSU (KEK, Japan)
Understand basics of superconducting magnet technologies for accelerator.
The course consists of 4 classes;
1) Basics of superconductors explains basic characteristics of superconductor.
2) Magnetic design and field quality explains how to build accelerator magnet field with superconducting technologies and summarizes the field quality issues associate with superconducting magnets.
3) Mechanics of superconducting accelerator magnet explains magnetic forces and stresses and summarizes the technologies to control them.
4) Quench stability and protection summarizes the source of quench and stability against it and then how to protect magnets.
Dr. Yasushi ARIMOTO (KEK, Japan)
SuperKEKB is a high-energy-electron(e-)/positron(e+) collider to produce copious pairs of B mesons. SuperKEKB is an upgrade of KEKB which has been operated until 2010 and is aiming at increasing a collision ratio of e-/e+ by 40 times compared with KEKB.
One key component of SuperKEKB is a final focus quadrupole system (QCS). The role of QCS is to squeeze the e-/e+ beams into vertical size of about 50 nm at a colliding point and this size is a twentieth of KEKB. QCS system consists of eight-superconducting-quadrupole magnets made of NbTi cables. A magnet which is located at the nearest position to the colliding point is 70 mm in diameter and is 400 mm in length. It can generate high magnetic gradient of 76 T/m. QCS has also 43 superconducting corrector magnets and four superconducting solenoid magnets to compensate solenoid field generated by a detector solenoid.
A construction of QCS started on June 2013 and it was complete on December 2016. We performed cold test and magnetic measurements until August 2017. Here, the development of QCS system will be introduced.
Dr. Michinaka SUGANO (KEK, Japan)
The High Luminosity upgrade of the Large Hadron Collider (HL-LHC) is ongoing to increase peak luminosity by a factor of five and integrated luminosity by a factor of ten in comparison with those in the present LHC. One of the key technologies to realize such outstanding performance is an upgrade of superconducting magnets at the insertion regions.
Various novel technologies will be applied for upgraded magnets such as the world’s first Nb3Sn accelerator quadrupole magnets, large aperture beam separation dipoles, orbit corrector magnets with a canted cos-theta design and so forth. In this lecture, first the HL-LHC project will be overviewed and then technological difficulties of each newly developing superconducting accelerator magnets will be explained.
Dr. Taro KONOMI (KEK, Japan)
An important property of superconductors is that the DC electrical resistance is zero. However, RF resistance in the microwave range has a finite value. This is the different from the DC case. The RF resistance of a superconducting accelerating cavity is approximately six orders lower than that of normal accelerating cavity. This benefit has a possibility to realize high gradient and high beam current accelerating cavity. In this lecture, the fundamental relationship between superconductivity and microwave based on superconducting cavity is introduced.
Dr. Hiroshi SAKAI (KEK, Japan)
In this lecture, I introduce the RF properties of superconducting cavities and the other important components like the input coupler, HOM coupler/damper. First, I show the basic important characteristics of RF cavities, which are based on Maxwell equations. The relation between RF fields in the cavity and accelerating beam is also expressed. Next, RF simulation methods and the results are shown by using various types of superconducting cavities. The RF simulation of input coupler and HOM coupler/damper will be presented.
Dr. Kensei UMEMORI (KEK, Japan)
Surface preparation techniques are explained. Polishing, heat treatment, ultra-pure water rinsing and so on, are applied to cavities to make smooth and clean surfaces. It is important to eliminate “defects” and “dust particles” on the surface, which sometimes limit cavity performances. New techniques of Nitrogen-doping and Nitrogen-infusion, which improve cavity performances, are also mentioned.
Dr. Yasuchika YAMAMOTO (KEK, Japan)
After passing the cavity performance test in the vertical cryostat, the cavity string assembly is done in the clean room, and it is installed into the cryo-vessel, called “cryomodule”. After the inspection of the high pressure gas regulation, the cryomodule is cooled down by the cryogenic system, and operated by the klystron/waveguide system. In this lecture, (1) work flow from the cavity string assembly to the cryomodule test, (2) the performance degradation in the cryomodule test, (3) the other issues and (4) the peripheral components like power coupler, frequency tuner, helium tank, Higher Order Mode (HOM) coupler will be presented in detail.
Dr. Hiroaki UMEZAWA (Tokyo Denkai, Japan)
This program explains high purity niobium for superconducting RF cavities. Niobium with a high thermal conductivity is required for the superconducting cavities to prevent thermal brake-down. Since the thermal conductivity at a cryogenic temperature is proportional to the residual resistivity ratio (RRR), which is easy to measure, the RRR is a practical index for evaluating niobium. The manufacturing process and evaluation methods including the RRR measurement for high purity niobium suitable for superconducting cavities will be explained in this lecture.
Dr. Katsuya SENNYU (Mitsubishi Heavy Industries Machinery Systems, Japan)
MHI-MS has had a lot of experience of fabrication for superconducting accelerators in Japan over 40 years. The contributions for the national projects in Japan and Asia region are indicated. Mechanical designs and fabrication techniques for superconducting accelerators including cavity, coupler, jacket, tuner and cryomodule are introduced. Most important technologies expected from accelerator scientists are described.
Dr. Soumen KAR (IUAC, India)
The basic concepts and theories of the cryogenics with the introduction to temperature-entropy diagram, basic thermodynamic processes e.g., isothermal, isentropic, isenthalpic processes, properties of useful cryogens etc. Production of colds, various liquefaction cycles, Carnot refrigeration cycle, liquefaction vs refrigeration, why the cryogenics is needed for any high energy particle accelerator.
Dr. Soumen KAR (IUAC, India)
The basics of 4K and 2K cryogenic system in reference to the particle accelerator, different mode of cryogenic heat transfer to 2K/4K cryogenic system; conduction, convection and radiation. Properties of cryogenic material: thermal expansion, thermal conductivity, specific heat, yield and ultimate tensile strength of various cryogenic material.
Dr. Rui GE (IHEP, China)
Dr. Rui GE (IHEP, China)
Dr. Takayuki TOMARU (KEK, Japan)
Dr. Nobuhiro KIMURA (KEK, Japan)
Prof. Yasuhiro MAKIDA (KEK, Japan)
Prof. Eiji KAKO (KEK, Japan)
Prof. Hirotaka NAKAI (KEK, Japan)