HB2014 - List of Authors (Shishlo, A.P.)

Paper

Title

Page

Status of PY-ORBIT: Benchmarking and Noise Control in PIC Codes

254

J.A. Holmes, S.M. Cousineau, A.P. Shishlo
ORNL, Oak Ridge, Tennessee, USA

Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
PY-ORBIT is a broad collection of accelerator beam dynamics simulation models, written primarily in C++, but accessed by the user through Python scripts. PY-ORBIT was conceived as a modernization, standardization, and architectural improvement of ORBIT, a beam dynamics code designed primarily for rings. Although this goal has been substantially achieved, PY-ORBIT has now incorporated additional capabilities. A major consideration in high intensity beam dynamics codes, such as PY-ORBIT and ORBIT, is the simulation of space charge effects. Computational space charge simulation is, of necessity, accompanied by noise due to discretization errors, which can compromise results over long time scales. Discretization errors occur due to finite step sizes between space charge kicks, due to graininess of the numerical space charge distribution, and due to the effects of spatial grids embedded in certain solvers. In order to simulate space charge, most tracking codes use solvers containing some or all of these effects. We compare the manifestation of discretization effects in different types of space charge solvers with the object of long time scale space charge simulation.

Slides WEO2LR02 [23.093 MB]

WEO3LR01

Beam Setup Conditions and Comparison of Deal and Actual Production Conditions

M.A. Plum, A.P. Shishlo
ORNL, Oak Ridge, Tennessee, USA

Funding: ORNL/SNS is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725.
This presentation will review methods for experimental determination of optimal operational set points in a multi-cavity superconducting high power hadron linac. A typical tuning process, including establishing correct acceleration profile and rms bunch size matching, is based on comparisons between measured data and results of simulations from envelope, single and multi-particle models. Presence of significant space charge effects requires simulation and measurement of bunch dynamics in three dimensions to ensure low loss beam transport. This is especially difficult in a superconducting linac where the use of interceptive beam diagnostics is usually restricted because of the risk of SRF cavity surface contamination. The procedures discussed here are based on non-interceptive diagnostics such as beam position monitors and laser wires, and conventional diagnostics devices such as wire scanners and bunch shape monitors installed outside the superconducting linac. The longitudinal Twiss analysis based on the BPM signals will be described. The superconducting SNS linac tuning experience will be used to demonstrate problems and their solution for real world linac tune-up procedures.

Slides WEO3LR01 [7.162 MB]

WEO3AB02

Status of Preparations for a 10 us H⁻ Laser-Assisted Stripping Experiment

299

S.M. Cousineau, A.V. Aleksandrov, V.V. Danilov, T.V. Gorlov, Y. Liu, A.A. Menshov, M.A. Plum, A. Rakhman, A.P. Shishlo
ORNL, Oak Ridge, Tennessee, USA
F.G. Garcia, N.F. Luttrell
UTK, Knoxville, Tennessee, USA
Y. Takeda
KEK, Ibaraki, Japan

At the Spallation Neutron Source accelerator preparations are underway for a 10 us laser-assisted H⁻ stripping experiment. This is a three orders of magnitude increase in pulse duration compared the to initial 2006 proof of principle experiment. The focus of the experiment is the validation of methods that reduce the average laser power requirement, including laser-ion beam temporal matching, ion beam dispersion tailoring, and specialized longitudinal and transverse optics. In this presentation we report on the status of preparations and the anticipated schedule for the experiment.

Slides WEO3AB02 [7.250 MB]

Paper	Title	Page
WEO2LR02	Status of PY-ORBIT: Benchmarking and Noise Control in PIC Codes	254
	J.A. Holmes, S.M. Cousineau, A.P. Shishlo ORNL, Oak Ridge, Tennessee, USA
	Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. PY-ORBIT is a broad collection of accelerator beam dynamics simulation models, written primarily in C++, but accessed by the user through Python scripts. PY-ORBIT was conceived as a modernization, standardization, and architectural improvement of ORBIT, a beam dynamics code designed primarily for rings. Although this goal has been substantially achieved, PY-ORBIT has now incorporated additional capabilities. A major consideration in high intensity beam dynamics codes, such as PY-ORBIT and ORBIT, is the simulation of space charge effects. Computational space charge simulation is, of necessity, accompanied by noise due to discretization errors, which can compromise results over long time scales. Discretization errors occur due to finite step sizes between space charge kicks, due to graininess of the numerical space charge distribution, and due to the effects of spatial grids embedded in certain solvers. In order to simulate space charge, most tracking codes use solvers containing some or all of these effects. We compare the manifestation of discretization effects in different types of space charge solvers with the object of long time scale space charge simulation.
	Slides WEO2LR02 [23.093 MB]

WEO3LR01	Beam Setup Conditions and Comparison of Deal and Actual Production Conditions
	M.A. Plum, A.P. Shishlo ORNL, Oak Ridge, Tennessee, USA
	Funding: ORNL/SNS is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725. This presentation will review methods for experimental determination of optimal operational set points in a multi-cavity superconducting high power hadron linac. A typical tuning process, including establishing correct acceleration profile and rms bunch size matching, is based on comparisons between measured data and results of simulations from envelope, single and multi-particle models. Presence of significant space charge effects requires simulation and measurement of bunch dynamics in three dimensions to ensure low loss beam transport. This is especially difficult in a superconducting linac where the use of interceptive beam diagnostics is usually restricted because of the risk of SRF cavity surface contamination. The procedures discussed here are based on non-interceptive diagnostics such as beam position monitors and laser wires, and conventional diagnostics devices such as wire scanners and bunch shape monitors installed outside the superconducting linac. The longitudinal Twiss analysis based on the BPM signals will be described. The superconducting SNS linac tuning experience will be used to demonstrate problems and their solution for real world linac tune-up procedures.
	Slides WEO3LR01 [7.162 MB]

WEO3AB02	Status of Preparations for a 10 us H⁻ Laser-Assisted Stripping Experiment	299
	S.M. Cousineau, A.V. Aleksandrov, V.V. Danilov, T.V. Gorlov, Y. Liu, A.A. Menshov, M.A. Plum, A. Rakhman, A.P. Shishlo ORNL, Oak Ridge, Tennessee, USA F.G. Garcia, N.F. Luttrell UTK, Knoxville, Tennessee, USA Y. Takeda KEK, Ibaraki, Japan
	At the Spallation Neutron Source accelerator preparations are underway for a 10 us laser-assisted H⁻ stripping experiment. This is a three orders of magnitude increase in pulse duration compared the to initial 2006 proof of principle experiment. The focus of the experiment is the validation of methods that reduce the average laser power requirement, including laser-ion beam temporal matching, ion beam dispersion tailoring, and specialized longitudinal and transverse optics. In this presentation we report on the status of preparations and the anticipated schedule for the experiment.
	Slides WEO3AB02 [7.250 MB]