Characteristics of Beam Modes at the ESRF

Beam mode & characteristics
Intensity
Lifetime
Beam

Uniform filling mode
992 bunches are equally distributed around the whole circumference of the storage ring.

Refill frequency: every hour 

200 mA

25 hours

Low emittance

εh = 130 pm.rad

ε = 10 pm.rad

 

7/8 + 1 filling mode

A train of 868 bunches (7/8 of the Storage Ring circumference) filled with 192 mA (0.23 mA / bunch).

The remaining 1/8 gap is filled in its center with a cleaned 8 mA-single bunch

Refill frequency: every hour
200 mA
24 hours
Low emittance

εh = 130 pm.rad

ε = 20 pm.rad

Hybrid mode 28*12 + 1 filling mode
One clean 8mA single bunch diametrically opposed to a ~ 192 mA multi-bunch beam composed of 28 groups of bunches spread over 3/4 of the storage ring circumference.

Refill frequency: every hour
200 mA
5 hours (single bunch) -> resulting lifetime ~ 17 hours Low emittance

εh = 130 pm.rad

ε = 20 pm.rad

16 bunch filling mode
16 highly populated and equally spaced bunches. Purity < 10-7

Refill frequency: every hour
75 mA
5.5 hours
Low emittance

εh = 135 pm.rad

ε = 20 pm.rad

4 bunch filling mode
4 highly populated and equally spaced bunches. 10 mA/bunch

Refill frequency: every hour
40 mA 5 hours Low emittance
 

εh = 135 pm.rad

ε = 20 pm.rad

MDT (Machine Dedicated time)
Operation for machine physics
Depending on programme
Depending on programme
Depending on programme
Shutdown
Shutdown period of the machine for maintenance, repairs, installation etc.
No beam
No beam
No beam