The figure shows top-up operation for a number of hours at the present maximum current. Plotted alongside the current is the product of current and lifetime. Presently we want high current to condition the ring. Conditioning can be thought of as a cleaning process of the inside of the vacuum chambers. This process is slow and the important parameter is number of hours with beam, i.e. time*current. When fully conditioned the stored current should be the same as in the 3 GeV storage ring, i.e. 500 mA.
Top-up has been used for a year already and it works very well. In present top-up operation we use a single dipole kicker, which disturbs the stored beam for a very short time at each injection, but in the future a more sophisticated injection scheme will be installed, which should make top-up invisible for the beamlines.
Present operation is heavily facilitated by a state machine software built and developed in-house (by Johan Sjögren, one of our operators) which provides automation for running the three accelerators in a coordinated manner. The state machine automatically handles the switching between delivery to the Short Pulse Facility (SPF) at the end of the linear accelerator and the top-up of both the 1.5 GeV and the 3.0 GeV storage rings. This means also switching between thermionic gun and photocathode gun running.
What is the remaining work to be done at the 1.5 GeV storage ring?
Much work remains. The optics should be fine-tuned And insertion devices for the beamlines will be installed, aligned and commissioned with beam.