[LCRC Accounts] Project Allocation Request
Hello, A change in allocation has been requested: Requester: borland (Michael Borland) Project: ApsRenewalLattice Title: Lattice Development and Beam Dynamics for APS Upgrade Description: APS has developed a method of using multi-objective genetic algorithms (MOGA) for optimization of accelerator lattices. We have also developed a systematic method of evaluating optimized lattices for robustness, using many ensembles that represent likely outcomes of commissioning. In the coming year, we will refine two multi-bend achromat (MBA) lattice designs that promise to push APS x-ray brightness to world-leading levels. Significant progress has already been made developing a design that is consistent with engineering constraints. The design has been presented at external reviews related to the on-going upgrade project. In FY17, there will be an emphasis on faster iteration with engineering changes, as well as refinement of physics models. A down-selection to a nominal design is expected in early FY17. It is likely that two lattices will be carried forward in the physics analysis to provide a point of comparison and backup in case issues arise with the nominal design (which is expected to be considerably more aggressive than the other candidate). The codes being used for MOGA and ensemble evaluation have all been used in past years on fusion. These include Pelegant, a parallel accelerator simulation code used primarily for particle tracking and acceptance determination, as well as a Tcl script used for genetic optimization. The simulations are close to embarrassingly parallel and thus scale very well. In addition to lattice development, we model the effects of the higher harmonic cavity (HHC), which plays a vital role in increasing the beam lifetime and reducing emittance blow-up. The simulations involve tracking beams consisting of 48 or more bunches of 100,000 or more particles each, and computing the collective electromagnetic interaction of these particles with the vacuum chamber and rf cavities. The methods are well advanced and will be employed with new lattices as they are generated. Detailed modeling has at present been performed mostly for the less aggressive of the two candidate lattices, and will need to be extended to the more aggressive lattice. Alternatives, such as a three-frequency system and low-frequency cavities, will continue to be explored. Beam loss analysis began will continue in FY17. This involves detailed and time-intensive simulation of the injection process and the Touschek scattering process. It also involves evaluation of beam loss collimation schemes, which are needed in order to protect accelerator components and reduce radiation outside the shielding wall. Current: undetermined amount Justification: The primary code being used, ELEGANT, has run successfully on fusion, blues, intrepid, mira, cory, franklin, and other systems. Most simulations are close to embarrassingly parallel, since they are of single-particle dynamics only. Simulations with collective effects show greater than 70% efficiency for 256 or more cores, depending on problem details. Requested: 1000000 A specific reason has been given: The APS Upgrade project is targeting completion of the preliminary design report (PDR) draft by May of this year in time for an external review. Completing the PDR is an FY17 lab goal. We need additional allocation this quarter to complete required calculations for the newly-adopted lattice. This needs to be approved and the final allocation amount decided upon. Thank You, The LCRC Accounts System
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