High-luminosity collider NICA operation for study of the gluon contribution to the nucleon spin will require very high intensity of the primary polarized proton and deuteron beams out of the source. A new technique is proposed for the polarized source upgrade as an important step to achieve designed NICA luminosity. It is based on the effect of the target thickness increase with transverse injection of the polarized atomic beam into the storage cell of the charge-exchange plasma ionizer. The atomic beam ionization is produced in charge-exchange collisions of atomic beam with ions in plasma jet. The atomic beam in the existing source is injected into the ionizer cell in longitudinal direction and produced beam is extracted in the backward direction [1,2]. Transverse injection of the atomic beam into the storage cell will eliminate a number of limitations inherent to the longitudinal injection configuration and deliver the beam intensity and polarization out of the source to obtain the high luminosity in the NICA collider.

Schematic layout of a polarized source with transverse injection of atomic beam into the T-shape storage cell.

In this scheme, a polarized atomic beam is injected into the storage cell perpendicularly to the direction of the plasma jet and the magnetic field axis of the ionizer solenoid. The plasma is generated in an arc discharge generator with a cold cathode and injected into the storage cell along the magnetic field axis. Polarized ions produced in the storage cell are held in the radial direction by a magnetic field and move to the electrode of the ion-optical system, in which polarized and non-polarized ions from the plasma are accelerated. The distance between the source of polarized atoms and the entrance to the storage cell in this scheme is significantly reduced compared to longitudinal injection, since the bending magnet and the ion extraction electrode system are not in the path of the atomic beam. The diameter of the emission electrode in this scheme is determined by the diameter of the plasma jet and can be reduced, resulting in a corresponding decrease in emittance of the beam. The energy of the extracted ions can be increased.  since the size of the bending magnet and of the ion-optical system  do not affect the atomic beam intensity. All these factors combined should produce about ten-fold increase of the beam quality factor:  QF= I·P²/Ԑ², where I -is the beam intensity, P- polarization, Ԑ – transverse emittance- to meet NICA luminosity design goal.

[1] A.S. Belov, D.E. Donets, V.V. Fimushkin, A.D. Kovalenko, L.V. Kutuzova, Yu.V. Prokofichev, V.B. Shutov, A.V. Turbabin and V.N. Zubets,  J. Phys..: Conf. Ser. 938, 012017 (2017). doi:10.1088/17426596/938/1/012017

[2] A.S. Belov, AIP Conf. Proc. 980, 209 (2008).  doi:10.1063/1.2888089

A.C. Belov, A.N. Zelenski, K.A. Ivshin, M.V. Kulikov, V.A. Lebedev, A.N. Solov'ev, E.M. Suresin, Yu.N. Filatov, V.V. Fimushkin
JETP Letters 122, issue 8 (2025)