Key points of announcement
- NanoTerasu, one of the world's best synchrotron radiation facilities, is scheduled to begin operations in fiscal 2024.
- By meticulously developing technology to adjust a 110 m-long linear accelerator with a precision of 100 micrometers or less, we succeeded in 3 GeV electrons acceleration 1 month earlier.
- By adopting a C-band accelerator tube, which has an acceleration frequency twice that of the one used in conventional accelerator facilities, we have reduced the overall length by about half, achieved significant compactness and reduced construction costs.
- The achievement of 3 GeV at the linear accelerator, which determines the electron beam energy of NanoTerasu circular accelerator, is a major milestone toward the realization of a high-brightness synchrotron radiation source in the soft X-ray wavelength region.
National Institutes for Quantum Science and Technology (President: Shigeo Dr. Koyasu, hereinafter "QST") is building and upgrading the world's best synchrotron radiation facility, NanoTerasu[1], for use by a wide range of researchers in industry and academia through a public-private regional partnership.
The accelerator group at the QST Institute for Advanced Synchrotron Light Source recently succeeded in accelerating electrons at 3 GeV at NanoTerasu Linear Accelerator.
On April 17, 2023, a high-density electron beam was generated from a high-performance electron source originally developed for NanoTerasu, and the acceleration of the electron beam was being adjusted through 40 C-band acceleration tubes of 2 meters in length. Then, on April 27, one month earlier than originally planned, the energy 3 GeV electron acceleration was confirmed using the lowest beam diagnostic equipment. After the systematic development, fabrication, and testing of major equipment, such as electron sources and acceleration tubes, we carefully developed technologies to adjust beams with a precision of less than 100 micrometers, which is important for beam adjustment, and to control the timing with a precision of 300 fs (1/3 trillion s) or less to match an electron beam close to the speed of light with a high-frequency accelerating electric field. By employing C-band acceleration tubes, which have an acceleration frequency twice that of conventional acceleration tubes used in accelerator facilities, we have reduced the overall length by about half, and have also achieved significant compactness and reduced construction costs.
NanoTerasu consists of a 110 m-long linear accelerator that accelerates electrons to 3 GeV and a 349 m-long circular accelerator that accumulates electrons and generates X-rays. The successful acceleration of the 3 GeV electron beam by the linear accelerator is a major milestone in achieving the target electron beam energy performance, and is a significant achievement in setting the stage for the planned start of operation of NanoTerasu from fiscal year 2024 by applying it to the testing of circular accelerators that require more precise beam adjustment. In the future, the linear accelerator will be adjusted in order to achieve more stable electron beam injection, and the start of electron beam injection and accumulation tests in the circular accelerator is scheduled in or after June this year.
[1]Official name: 3GeV synchrotron radiation facility. “NanoTerasu” is a nickname.
Terminology
１）Public-Private Regional Partnerships
The project consists of regional partners, including Miyagi Prefecture, Sendai City, Tohoku University, and Tohoku Economic Federation, represented by the national governments National Institutes for Quantum Science and Technology (QST) and Photon Science Innovation Center (PhoSIC), and is being developed based on a division of roles, including cost sharing. QST, the national government entity, is responsible for the development of the accelerator and three shared beamlines, while the regional partners are responsible for the development of the site, basic building, and seven coordination beamlines.
２）Synchrotron radiation
Synchrotron radiation is an electromagnetic wave emitted in the traveling direction when an electron beam accelerated to near the speed of light is bent by a magnet, and has excellent characteristics such as high brightness, high directivity, and the ability to freely change the deflection characteristics.
３）Soft and hard X-rays
Among X-rays with wavelengths from 1 pm to 10 nm, those shorter than 0.2 nm are called hard X-rays and those longer are called soft X-rays.
４）Electron beam concentrator (bunching system), subharmonic buncher
By injecting an electron beam pulse into the acceleration/deceleration phase of a high-frequency electric field generated in a high-frequency cavity, it is possible to give different energies to electrons in the electron beam pulse. By applying a deceleration electric field to the front electrons and an acceleration electric field to the rear electrons, the rear electrons catch up with the front electrons while the entire electron pulse moves forward. This operation produces a short-pulse electron beam.
５）fs
A unit of time. 1 fs (femtosecond) is 1/1000 trillion of a second.