Linear Accelerator

The SSRF linac consists of a 100 kV electron gun, a 500 MHz sub-harmonic buncher cavity, a fundamental buncher section and four 3 GHz SLAC-type accelerating sections powered by two 45 MW klystrons. The linac accelerates the electrons to the energy of 150 MeV, with beam emittance less than 50 mm-mrad, relative energy spread less than 0.5% and energy stability better than 0.5%. The linac can operate in two modes: single bunch mode with bunch charge larger than 1 nC and pulse width of less than 1 ns, and a multi-bunch mode with total charge larger than 10 nC in more than 100 bunches in a pulse width of 200 ns. The repetition rate of the linac pulse can be varied up to 10 Hz. Electrons with energy of 150 MeV are guided towards the booster via low energy transfer line.

The main specifications are listed in the following table

Nominal energy (MeV)		150
Pulse length (ns)	Single bunch	1
	Multi bunch	200
Beam charge (nC)	Single bunch	1
	Multi bunch	10
Pulse to pulse energy stability (rms)		0.5%
Relative energy spread (rms)		0.5%
Normalized Emittance (mm×mrad)		< 50
Frequency (MHz)		2997.924
Repetition Rate (Hz)		1~10

 

 

Booster

The SSRF full energy booster is a 2 Hz synchrotron, which accelerates electrons from the linac to the final energy of 3.5 GeV. It has a circumference of 180 meters and consists of 28 FODO cells with a variety of items such as RF cavities, vacuum components, magnets, injection and extraction systems, beam diagnostic system. The booster also can work in two modes: single bunch mode with a charge of 1 nC and a multi-bunch mode with a total charge above 5 nC. To obtain 3.5 GeV energy, electrons must circulate about 0.4 million turns in the booster, the whole process lasts 250 ms and is periodically repeated 2 times per second. After extraction from the booster, the electrons areguided to a high energy transfer line towards the storage ring.

The main specifications are listed in the following table

 

 

Storage Ring

The core of the SSRF complex is a 3.5 GeV storage ring with a circumference of 432 meters. The storage ring lattice is a 20-cell double bend achromat lattice structure with 4 super-periods and each super-period contains a 12 meters long straight section and four 6.5 meters standard straight sections. Two of the long straight sections have been used for accommodating injection elements and for installing three superconducting RF cavities respectively, the other eighteen straight sections are used to install various insertion devices. Each of the 20 storage ring double bend lattice cells consists of two bending dipole magnets, ten quadrupole magnets, seven sextupole magnets and seven pairs of corrector magnets, 4 of them are slow correctors, others are fast correctors. The storage ring is equipped with three superconducting RF cavities in a 12 m-long straight section to provide the beam with a voltage of 4-6 MV and a total beam power up to more than 600 kW. The injection system consists of two septum magnets and four kicker magnets and is optimized for top-up operation. The storage ring has a natural emittance of 3.9 nm-rad and can operate at a multi-bunch current up to 300 mA or at a single bunch current of 5 mA. A sophisticated beam diagnostic system and an orbit feedback system keep the position of the electron beam constant to less than 1 µm (RMS), which guarantees a very high stability of the electron orbit.

 

The main specifications are listed in the following table