|Shutdown 2013 Update|
|Friday, 01 March 2013 15:43|
The ALS is replacing all of the corrector magnets with sextupoles (48 of them) to allow for tighter horizontal control of the beam, thereby increasing beam brightness. This so-called "lattice upgrade" will also increase beam brightness by concentrating the horizontal emittance.
Cold head replacement
The cooling elements in the three superbend magnets (and one spare) need to be replaced every 18 months or so, a factor that must be considered when setting the ALS shutdown schedule. These "cold heads" cool the 1.5-ton superbends to an operating temperature of 4K, pumping in liquid phase nitrogen and helium. To replace the cold heads, each must first be warmed up to room temperature, which takes about three days if heating is circulated (it would take about 10 days if left to warm on its own). Crews can then remove the old cold head and ship it off to the manufacturer for refurbishing (like a cold head recycling program). The new piece is installed in its place, the magnets are cooled back down to 4K, and power is restored.
New klystron power supply
As part of the storage ring radio frequency (rf) upgrade, the ALS installed a new high-voltage power supply that will support the use of two new klystrons instead of the single original klystron installed in 1992. Klystrons are used to provide rf cavities with microwaves that "kick" electrons to boost or maintain their speed. The storage ring has two rf cavities, and the next portion of the upgrade will involve installing a switch that allows operation of one or both cavities on either klystron, if necessary, but with normal operation being one klystron per cavity.
Sector 7 upgrade
Beamline 7 has been disassembled to make way for MAESTRO (nanoARPES) and COSMIC (Coherent Scattering and Microscopy). One major part of this work was to remove the insertion device from this sector. The giant undulator was hoisted out of the storage ring by a 30-ton crane and positioned on a support slab. Eventually, it will be shipped to another light source for use.
As you can see, this 47,000-pound device was one of the original insertion devices used at the ALS, installed in 1993.
Sector 7 will be chicaned and will receive two new insertion devices where there previously was one. MAESTRO will receive a next-generation nanoARPES chamber in addition to the existing µARPES endstation, new optics, and a sample transfer system. Here are some photos of the front end.