Megascience shared research center "Siberian Synchrotron and Terahertz Radiation Centre" (SRC SSTRC), a "4+" generation source of synchrotron radiation with 3 GeV energy, requires an injection system which will accelerate particles to the energy of 200 MeV stated at the performance specifications.
Specialists of the Budker Institute of Nuclear Physics of the Siberian Branch of the RAS (BINP SB RAS) developed a stand for one of the injector elements where the main acceleration will occur. Scientists have identified the basic requirements for the production of accelerating structures to achieve the required level of acceleration. The obtained analytical data will allow to create the injector providing the set parameters of a beam and stable operation of a source of synchrotron radiation of SRC SSTRC. Part of the work on measuring the accelerating structure was carried out by Kristina Grishina, Novosibirsk State Technical University NETI postgraduate, Physical Engineering Faculty, and senior laboratory assistant at BINP SB RAS. The injector of the future Siberian ring photon source is an electronic high-frequency gun, a beam grouping system and regular accelerating sections. It is in this last element of the injection system (the accelerating structure) that the main acceleration to 200 MeV energy will occur.
"The accelerating structure in the injector allows reaching the necessary energy. Only after that the particle beam gets into the storage ring and then into the synchrotron ring of the installation where the radiation is generated," says Alexey Levichev, PhD (Physics and Mathematics) the head of the Science Department, BINP SB RAS. "In order to achieve the required energy parameter in the SRC SSTRC project, we assumed that we needed five accelerating structures, each of which would yield about 40 MeV".
BINP SB RAS experts have developed a stand to determine precisely what energy the accelerating structures will be able to accumulate and what parameters they should have. All the necessary measurements were taken at this stand. The investigated element of the injection system is a three-meter diaphragm-type waveguide with an electromagnetic field inside, which is suitable for beam acceleration.
"Our stand has been assembled on the basis of the structure that remained after the development of VEPP-5 BINP SB RAS injection complex" , says Kristina Grishina, a postgraduate of Physical Engineering Faculty, NSTU NETI, senior laboratory assistant, BINP SB RAS . "The parameters of the accelerating structurev"old" version (its phase and group velocity, coupling coefficient, etc.) were measured a long time ago. We started measuring these parameters to clarify whether using such structures in the SRC SSTRC injection system will give the necessary level of acceleration. We also needed to understand how to modify them if necessary".
The main data were obtained at the measuring stand created at the BINP SB RAS. It includes a stepper motor to stretch the disturbing body, a controller to control the stepper motor, an S-parameter analyzer and a cable track.
"When forming necessary beam parameters, we can always have some drift in energy, so it can be less or more than the specified parameters", adds Kristina Grishina. "Doing this work we have established how the error in the phase incursion affects the beam formation drift, and the reason of the error is the different radius of the accelerating structure cells. That is, because of the different radius of the cells, we lose the energy of the beam". According to Grishina, it is impossible to make all the cells (about 400) similar. "But we can correct the radius of each cell by adjusting frequency. Special platforms will compress the cell, deforming its geometry, due to which the frequency will change", explains Kristina.
The measurements have shown that the accelerating structures of the injection system will be able to achieve the energy level that meets the project parameters.
"Now we have the data about the energy we can really obtain," says Alexey Levichev. "The project of accelerating structures has been approved for production and is already being manufactured." The scientist also noted that part of the work on the accelerating structure parameters measuring was carried out by NSTU NETI student, which is very important in the view of training for SRC SSTRC and other ambitious projects. "We need young specialists who will be able to participate in the manufacture, launch and operation of the fourth generation SR source," adds Alexey Levichev.
The SRC SSTRC project is created within the framework of the "Science" National Project with the aim of implementing a modern national network of new generation synchrotron radiation sources in Russia and is the flagship of the development program of the Novosibirsk scientific center, known as "Akademgorodok 2.0". SRC SSTRC is a shared research center which will include not only the accelerator complex, but also a developed user infrastructure, such as experimental stations and laboratory facilities. The creation of the SR source is planned to be completed in 2023, which will allow starting scientific research in 2024. The indicative cost of the project is estimated at 37.1 billion rubles.