PF ring

PF Storage Ring

The 2.5-GeV PF storage ring is a dedicated synchrotron radiation (SR) source which can supply highly-brilliant X-ray and VUV light to scientists in such fields as physics, chemistry, biology and medical science. There are 22 beamlines which are open to worldwide scientists, which includes 8 beamlines from insertion devices and 14 beamlines from bending magnets.

The spatial and temporal stability of the SR is most important for the light sources. In the Photon Factory storage ring, excellent beam stability and intensity have been achieved. It has the following unique features:

The beam positions are very stable. In order to stabilize the beams, we use a very-precise global feedback system which can correct any beam movement of the frequency up to 1 Hz.
High beam current: 400 mA under usual operation, and achieved 770 mA under machine study.
Beam lifetime is very long: about 50 hours at the beam current of 400 mA.
The storage ring is very reliable: down time is typically less than 2% of the scheduled operation.
Beam instabilities are well controlled even at the maximum beam current. This is achieved by using four 500-MHz damped accelerating cavities which are free from cavity-induced beam instabilities.

The PF storage ring was initially commissioned in 1982, and it was largely reconstructed in 1997 in order to obtain much lower beam emittance. Due to this improvement, the beam emittance was reduced from 130 to 36 nm*rad. (Note that the available minimum emittance is 27 nm*rad). The new PF storage ring was commissioned in October, 1997. The PF ring can now provide much brilliant synchrotron light.

The PF storage ring usually stores 2.5-GeV electron beams under multi-bunch operation. A part of the scheduled operation is made under single-bunch operation or under higher energy (3 GeV) operation.

Parameters of the PF Storage ring

Beam energy 2.5 GeV (0.75 - 3.0 GeV)

Initial beam current 450 mA (achieved 770 mA)

Beam emittance (design value) 36 nm*rad (105 deg./cell optics)

Number of bending magnets 28

Number of rf accelerating cavities 4

rf frequency 500.1 MHz

Circumference 187 m

Number of insertion devices 8

Beam lifetime 50 h (at I=400mA)

Average ring pressure 6 x 10^-8 Pa (at 400 mA)

Radiation loss per turn 400 keV

Stability of SR beam position beam drift is less than 20 micro m during the whole day
(at 20 m from SR source point)

See Photon Factory Activity Report 2003 "Outline of the Accelerators" for more details.

Typical Operation

A typical ring operation during one week (from Monday to Sunday) is shown below. Machine study is usually scheduled on Monday. During user runs, beams are injected once a day, at 9:00 AM. Initial stored current is 450 mA, and the beam current of about 300 mA remains after the beam storage during 24 hours.

Latest Informations

Last modified 2002-03-04 by

Beam energy	2.5 GeV (0.75 - 3.0 GeV)
Initial beam current	450 mA (achieved 770 mA)
Beam emittance (design value)	36 nm*rad (105 deg./cell optics)
Number of bending magnets	28
Number of rf accelerating cavities	4
rf frequency	500.1 MHz
Circumference	187 m
Number of insertion devices	8
Beam lifetime	50 h (at I=400mA)
Average ring pressure	6 x 10^-8 Pa (at 400 mA)
Radiation loss per turn	400 keV
Stability of SR beam position	beam drift is less than 20 micro m during the whole day (at 20 m from SR source point)