The Multibunch filling pattern which represents 67% of the total user time is now delivered mostly in uniform filling with a lifetime greater than 70 hours at 200 mA (provided that the GRAAL laser is not being powered). Despite a slightly lower lifetime, the 2*1/3 fill is still used for time-structure experiments. The remaining 33 % is shared between the 16 bunch, the single bunch and the hybrid-mode filling patterns (Figure 132).

Fig. 132: Distribution of the 2002 user time in the various filling modes.

A new hybrid filling pattern based on groups of bunches was fully assessed during 2002 (24 groups of 8 bunches and a single bunch in the gap). The lifetime is in the order of 20 hours for a total current of 200 mA. The "cleaning" which removes electrons from the unwanted buckets (to a level better than 10­6 compared to the filled buckets) was, a long-standing difficulty that was solved by exciting the beam at a high frequency through the newly-installed stripline shaker. This filling mode will be tested in user time in 2003.