Storage ring

The storage ring is a heart of the National Synchrotron Radiation Centre SOLARIS. It is a replica of the 1.5 GeV storage ring built at MAX IV Laboratory in Lund, Sweden, which has 6nm rad emittance and 96 m circumference. The main purpose of the storage ring is to accumulate and to maintain the circulating beam as long as possible, which is the source of synchrotron radiation in the VUV and soft-X ray rang. 

MAGNETS
 

The storage ring is a 3rd generation light source designed to obtain a low emittance electron beam circulating in the machine of the relatively small size. This results in the ultra-compact lattice design consisting of 12 identical Double-Bend Achromat (DBA) cells.

 

The typical DBA cell contains two bending magnets flanked with strong focusing quadrupoles in both planes as well as sextupoles for the chromaticity correction and the dynamic aperture improvement. In order to reduce number of magnets the novel technology of magnets integration in one solid iron block was implemented. Moreover combined function magnets, such dipoles (DIP) with defocusing gradient, and focusing quadrupoles (SQFo and SQFi) with focusing sextupole content are used.

Additionally,  the correction dipoles (COR) are integrated into small correction sextupoles (SCo and SCi) as an additional coils. The defocusing sextupoles  (SDo & SDi) are designed as separate magnets flanking dipoles. Apart from the magnets, the DBA cell is also equipped with three beam position monitors (BPM).  The DBA cell's layout  is presented in the Figure 1, whereas the 3D magnets block design is shown in the Figure 2.

Figure 1: The layout of the DBA cell in the Solaris storage ring.
 

Figure 2:  The lower part of the SOLARIS storage ring magnet, length: 4.5 m, weight: 4T.

DBA cells  are separated by 3.5 m long straight sections. 3 of 12 straights are used for the RF system and injection, whereas 9 is fully reserved for various insertion devices (ID). Electrons coming from linear accelerator are injected to the storage ring by using the DC Lambertson septum magnet, which is located in the 1st straight section. In order to place the beam on a proper orbit the injected beam is kicked by the pulsed dipole kicker magnet which is located in the 3rd straight section.

RADIO FREQUENCY SYSTEM

 

The SOLARIS synchrotron is also equipped  with two 100 MHz main cavities. The main tasks of RF cavities is to provide an energy boost which compensates for the energy losses of the circulating electrons, and  allows the beam to maintain a fixed orbit around the storage ring. The electromagnetic field is generated and transferred to the cavity by the high power transmitter. Additionally, two passive Landau cavities for the bunch elongation were installed in the SOLARIS storage ring. The design of both types cavities is presented in the Figure 3.

Figure 3: Two types of cavities used in the Solaris storage ring.
 

VACUUM SYSTEM
 

Vacuum chambers were manufactured from the high quality stainless steel (Fig. 4). Partially the vacuum chambers are NEG (Non Evaporable Getter) coated. This novel NEG technology results in reduction of vacuum pumps quantity used in the synchrotron facilities.

Figure 4: The layout of the standard vacuum chamber in the Solaris storage ring.
 

The vacuum system contains two kinds of light ports – the 7.5° ports for the photons emitted from the bending magnet and 0° ports for the photons emitted from the IDs, such as undulators or wigglers.

Tab. Main parameters of the SOLARIS storage ring

 
Parameter Value
Energy 1.5 GeV             
Current 500 mA
Circumference 96 m
RF Frequency 99.98 MHz
Harmonic number 32
Horizontal emittance (bare lattice) 6 nm rad
Coupling 1%
Tune Qx, Qy 11.22, 3.15
Natural chromaticity ξx, ξy -22.96, -17.14
Beam size in the straight section centre  σx, σy 184 µm, 13 µm
Momentum compaction 3.055 x 10-3
Momentum acceptance 4%
Total lifetime 13 h