2017-Feb-18 Comp. Phys. Biweekly Report

He Zhang:

• Cooling simulation - Now the program can track the ions by a turn-by-turn method during cooling. The program will take the betatron oscillation tunes and the synchtron oscillation tune, construct the transfer matrix, and use it in tracking. Later we can add a feature of tracking with maps, if necessary to study some other effects.
• Dust particle transport Read through some papers again, focusing on the following three topics: pick-up of the dust particle, transverse stability of the dust particle’s motion, and longitudinal motion of the dust particle. Basically, the dust particle could be picked up due to its own thermal energy or the field of the beam. . Because the longitudinal velocity of the dust particle is much slower than that of the beam, during the time for the dust particle to transport a few meters, many (probably up to a million) electron bunches have passed the dust particle. Each bunch gives it a kick. If the motion is not stable, it is difficult to image the dust particle can survive so many kicks. Now I think the motion should be stable and a critical charge to mass ratio could be calculated. If the charge density of the beam is not uniform, it will give the dust particle accelerations in the longitudinal direction. Once I finish the summary, I’ll discuss with Rongli what to calculate. (meeting is scheduled monday at 11am)
• NSF proposal - Finished and submitted the NSF proposal on “Mesh-free method for space charge effect simulation with boundary of arbitrary geometry”. Based on the review, I think there are two things to improve. First, the reviewers want a specific example that will benefit from this method. Second, the reviewers think we just use old algorithms and do not contribute to computational physics. I basically worked on the second point. Add descriptions on the new algorithms, traceless FMM for Coulomb interaction and kernel independent FMM using differential algebra. We fail to make solid improvement on the first point. So I think we will take time to improve the proposal, although it has been submitted.
• Cooling theory study - Continue the study and had a meeting with Slava, Yuhong and Vasiliy. We discussed an old paper from Slava. But later we decided to study Slava’s thesis, since there is a more complete and systematic description of the theory.
• Trip rate/heat load optimization - I started to write an IPAC’17 paper on the trip rate/heat load optimization. (Finished one page till now.) Submit a proposal for SULI summer studentDust particle transport

Yves Roblin

• CEBAF: working on improvements to optics model. In particular ways to exploit the signals from the M56 cavities to do global tunings of the arcs.
• BEM algorithms being reviewed still. We now have a second version of BEM which runs in parallel with the real one in order to study the adequacy of the algorithms parasitically.
• JLEIC:
  Organizing meetings for the simulations.
  Installed Beam Beam 3D on the JLAB clusters
  Starting running BB3D simulations of the EIC 100/5 setup.
  Working on extracting generating functions from a symplectic map. This is something we would like to do in order to have GHOST directly use maps coming from MAD-X instead of COSY.
  Read the EIC report. Preparing a list of simulation related activities one has to prioritize according to this report.