Linear UHF-accelerators are used in various spheres of activity ranging from industry and medicine to colliders and synchrotron radiation sources. One of the key performance indicators of any linear accelerator is low particle losses during acceleration. To increase this indicator, Budker Institute of Nuclear Physics SB RAS (BINP SB RAS) specialists - developed a special section for the beam pre-acceleration and non-relativistic continuous grouping. Such sections can be used with different types of regular acceleration structures. According to the preliminary calculations, the use of this section will increase the passage of current to at least 85%, which is a very high value. The International Salon of Inventions and New Technologies "New Time" distinguished the research results of Kristina Grishina, the Faculty of Physics and Technology, NSTU NETI graduate student, BINP SB RAS Senior Laboratory Assistant, with a Special Award from Journalists.
Acceleration of charged particles occurs under the action of an electric field in special resonant cells in which this field is formed and stored. If the electrons already have large values of kinetic energy (relativistic), then the acceleration process can be carried out in identical cells without particle loss forming regular accelerating structures. This greatly facilitates the production of the accelerator. Importantly, the particle energy does not reach high values at the outset of the electron beam formation. In this case, the acceleration in such regular structures will not be optimal, since considerable electron losses will occur. As a result, the number of accelerated particles can be estimated at about 30% of the original amount.
BINP SB RAS has a vast experience in development and manufacturing various types of regular accelerating structures. Recently, this experience became a starting point in the development of a device for minimizing the acceleration losses of electrons whose initial energy is small. The developed device aims at increasing the acceleration efficiency of the linear microwave accelerator which is currently operating at the BINP SB RAS for injecting charged particles into the VEPP-4 and VEPP-2000 colliders. In addition, this technology can be useful for creating industrial accelerators, for which this indicator has particular importance, as well as for implementing future projects of the Institute. To reduce particle losses, BINP SB RAS researchers are conducting research on non-periodic structures that were not previously applied at the Institute. The calculations performed during the research yielded the preliminary results which claim the possibility of obtaining the value of at least 85 % of the beam current.
"Many linear microwave accelerators require a large pulse or average power in the beam and pulse currents of 0.1-2 A," explains Kristina Grishina, a graduate student at FTF NSTU. – My work is to create a matching section that a non-relativistic continuous beam converts into a sequence of bunches with an energy of about 1 MeV, after which regular accelerating structures can be applied without loss of particles. At the moment, the structure is fully developed, and we are currently at the production stage. The beginning of 2021 is likely to see the structure assembly and further measurements. It is important for us to find out whether we are able to make such structures with variable pitch and variable field in the BINP. So far, it was only about simulation, while production and real-world measurements may have their own difficulties. We will find it out when we assemble the facility".
Alexey Levichev, PhD (Physics and Mathematics), head of the BINP SB RAS sector, noted that the structure developed by Kristina Grishina is of great interest, first of all, for the Institute of Nuclear Physics. "The point is," he explained, that we have no experience in creating such pre-accelerator grouping devices. Based on this prototype, we are essentially developing new technologies and gaining new experience. The complexity of this product is that all the resonators that make up the structure have different sizes. The task of developing a pre-accelerator grouping device includes setting up such a structure, conducting the measurement and achieving the necessary electrodynamic parameters. This technology can be applicable to all accelerators where a large accelerated electron current is required. For example, for a future сollider A Charm Tau Factory or setting with muons (µ-µ-tron) will need to generate a large number of positrons. Their number is determined by the current of accelerated electrons. So, the experience that we get on the basis of our pre-accelerator-grouper will also be very useful”.
Kristina Grishina presented the results at the International Salon of Inventions and New Technologies «New Time», which was held with the support of Rospatent, the Ministry of Defense and the Ministry of Education and Science of Russia, where she won the special award from journalists for the best presentation.
"The contribution of Kristina is very significant", – comments Alexey Levichev, her academic adviser. "She is the one who is responsible for the whole project, from initial calculations to the work with the designer and production. I want to say that this is hard work that requires many skills: the ability to quickly navigate the situation, communication skills, and the ability to think outside the box to find solutions. No matter how good you are at physics, you may still know little about achieving other goals. Kristina is different, you only show her the direction, and she will lead the way herself. This is her forte".