Paper  Title  Other Keywords  Page 

TUZBB6  Nonlinear TuneShift Measurements in the Integrable Optics Test Accelerator  experiment, optics, lattice, electron  368 


Funding: US Department of Energy, Office of High Energy Physics, General Accelerator Research and Development (GARD) Program The first experimental run of Fermilab’s Integrable Optics Test Accelerator (IOTA) ring aimed at testing the concept of nonlinear integrable beam optics. In this report we present the preliminary results of the studies of a nonlinear focusing system with two invariants of motion realized with the special ellipticpotential magnet. The key measurement of this experiment was the horizontal and vertical betatron tune shift as a function of transverse amplitude. A vertical kicker strength was varied to change the betatron amplitude for several values of the nonlinear magnet strength. The turnbyturn positions of the 100 MeV electron beam at twentyone beam position monitors around the ring were captured and used for the analysis of phasespace trajectories. 

Slides TUZBB6 [12.888 MB]  
DOI •  reference for this paper ※ https://doi.org/10.18429/JACoWNAPAC2019TUZBB6  
About •  paper received ※ 28 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019  
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TUPLM09  A Fast Method to Evaluate Transverse CoupledBunch Stability at NonZero Chromaticity  synchrotron, wakefield, dipole, simulation  387 


Funding: Supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DEAC0206CH11357 We present a dispersion relation that gives the complex growth rate for coupledbunch instabilities at arbitrary chromaticity in terms of its value at zero chromaticity. We compare predictions of the theory to elegant tracking simulations, and show that there are two distinct regimes to stability depending upon whether the zero chromaticity growth rate is smaller or larger than the chromatic tune shift over the bunch. We derive an approximate expression that is easily solved numerically, and furthermore indicate how the formalism can be extended to describe arbitrary longitudinal potentials. 

DOI •  reference for this paper ※ https://doi.org/10.18429/JACoWNAPAC2019TUPLM09  
About •  paper received ※ 25 August 2019 paper accepted ※ 01 September 2019 issue date ※ 08 October 2019  
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WEPLM02  Finding Beam Loss Locations in a Linac with Oscillating Dipole Correctors  linac, dipole, DTL, radiation  663 


Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DEAC0207CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics The paper proposes a method of finding the beam loss locations in a linac. If the beam is scraped at an aperture limitation, moving its centroid with two dipole correctors located upstream and oscillating in sync produces a line at the corresponding frequency in spectra of currentsensitive devices downstream of the loss point. The phase of this signal contains information about the location of the beam loss. Similar lines appear also in the position signals of Beam Position Monitors (BPMs). The phases of the BPM position lines change monotonically (within each 2π) along the linac and can be used a reference system. The phase of the loss signal compared with this reference system pinpoints the beam loss location, assuming that longitudinal coordinates of the BPMs are known. If the correctors deflection amplitudes and the phase offset between their waveforms are chosen optimally and well calibrated, the same measurement provides values of the βfunction and the betatron phase advance at the BPM locations. Optics measurements of this type can be made parasitically, with negligible effect on the emittance, if a long measurement time is acceptable. 

DOI •  reference for this paper ※ https://doi.org/10.18429/JACoWNAPAC2019WEPLM02  
About •  paper received ※ 27 August 2019 paper accepted ※ 19 November 2019 issue date ※ 08 October 2019  
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WEPLS03  Analytical Expression for a NTurn Trajectory in the Presence of Quadrupole Magnetic Errors  quadrupole, experiment, simulation, lattice  772 


The action and phase jump method is a technique, based on the use of turnbyturn experimental data in a circular accelerator, to find and measure local sources of magnetic errors through abrupt changes in the values of action and phase. At this moment, this method uses at least one pair of adjacent BPMs (Beam Position Monitors) to estimate the action and phase at one particular position in the accelerator. In this work, we propose a theoretical expression to describe the trajectory of a charged particle for an arbitrary number of turns when a magnetic error is present in the accelerator. This expression might help to estimate action and phase at one particular position of the accelerator using only one BPM in contrast to the current method that needs at least two BPMs.  
DOI •  reference for this paper ※ https://doi.org/10.18429/JACoWNAPAC2019WEPLS03  
About •  paper received ※ 26 August 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019  
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