ErrorInduced Beam Degradation in Fermilab's Accelerators
Abstract
In Part I, three independent models of Fermilab's Booster synchrotron are presented. All three models are constructed to investigate and explore the effects of unavoidable machine errors on a proton beam under the influence of spacecharge effects. The first is a stochastic noise model. Electric current fluctuations arising from power supplies are ubiquitous and unavoidable and are a source of instabilities in accelerators of all types. A new noise module for generating the OrnsteinUhlenbeck (OU) stochastic noise is first created and incorporated into the existing Objectoriented Ring Beam Injection and Tracking (ORBITFNAL) package. After being convinced with a preliminary model that the noise, particularly nonwhite noise, does matter to beam quality, we proceeded to measure directly current ripples and commonmode voltages from all four Gradient Magnet Power Supplies (GMPS). Then, the current signals are Fourieranalyzed. Based upon the power spectra of current signals, we tune up the OrnsteinUhlnbeck noise model. As a result, we are able to closely match the frequency spectra between current measurements and the modeled OU stochastic noise. The stochastic noise modeled upon measurements is applied to the Booster beam in the presence of the full spacecharge effects. This noise model, accompanied by a suite of beammore »
 Authors:

 Univ. of Rochester, NY (United States)
 Publication Date:
 Research Org.:
 Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
 Sponsoring Org.:
 USDOE
 OSTI Identifier:
 921701
 Report Number(s):
 FERMILABTHESIS200743
TRN: US0800797
 DOE Contract Number:
 AC0207CH11359; AC0276CH03000; FG0291ER40685
 Resource Type:
 Thesis/Dissertation
 Country of Publication:
 United States
 Language:
 English
 Subject:
 43 PARTICLE ACCELERATORS; ACCELERATORS; ADIABATIC PROCESSES; ALIGNMENT; ANTIPROTON SOURCES; ANTIPROTONS; BEAM INJECTION; CHARGE DENSITY; ELECTRIC CURRENTS; FERMILAB; FLUCTUATIONS; LINEAR ACCELERATORS; MAGNETS; POWER SUPPLIES; PROTON BEAMS; PROTONS; SPACE CHARGE; SPECTRA; SYNCHROTRONS; TANKS; Accelerators
Citation Formats
Yoon, SungYoung Phil. ErrorInduced Beam Degradation in Fermilab's Accelerators. United States: N. p., 2008.
Web. doi:10.2172/921701.
Yoon, SungYoung Phil. ErrorInduced Beam Degradation in Fermilab's Accelerators. United States. https://doi.org/10.2172/921701
Yoon, SungYoung Phil. Tue .
"ErrorInduced Beam Degradation in Fermilab's Accelerators". United States. https://doi.org/10.2172/921701. https://www.osti.gov/servlets/purl/921701.
@article{osti_921701,
title = {ErrorInduced Beam Degradation in Fermilab's Accelerators},
author = {Yoon, SungYoung Phil},
abstractNote = {In Part I, three independent models of Fermilab's Booster synchrotron are presented. All three models are constructed to investigate and explore the effects of unavoidable machine errors on a proton beam under the influence of spacecharge effects. The first is a stochastic noise model. Electric current fluctuations arising from power supplies are ubiquitous and unavoidable and are a source of instabilities in accelerators of all types. A new noise module for generating the OrnsteinUhlenbeck (OU) stochastic noise is first created and incorporated into the existing Objectoriented Ring Beam Injection and Tracking (ORBITFNAL) package. After being convinced with a preliminary model that the noise, particularly nonwhite noise, does matter to beam quality, we proceeded to measure directly current ripples and commonmode voltages from all four Gradient Magnet Power Supplies (GMPS). Then, the current signals are Fourieranalyzed. Based upon the power spectra of current signals, we tune up the OrnsteinUhlnbeck noise model. As a result, we are able to closely match the frequency spectra between current measurements and the modeled OU stochastic noise. The stochastic noise modeled upon measurements is applied to the Booster beam in the presence of the full spacecharge effects. This noise model, accompanied by a suite of beam diagnostic calculations, manifests that the stochastic noise, impinging upon the beam and coupled to the spacecharge effects, can substantially enhance the beam degradation process throughout the injection period. The second model is a magnet misalignment model. It is the first time to utilize the latest beamline survey data for building a magnetbymagnet misalignment model. Given asfound survey fiducial coordinates, we calculate all types of magnet alignment errors (station error, pitch, yaw, roll, twists, etc.) are implemented in the model. We then follow up with statistical analysis to understand how each type of alignment errors are currently distributed around the Booster ring. The ORBITFNAL simulations with space charge included show that rolled magnets, in particular, have substantial effects on the Booster beam. This surveydatabased misalignment model can predict how much improvement in machine performance can be achieved if prioritized or selected realignment work is done. In other words, this model can help us investigate different realignment scenarios for the Booster. In addition, by calculating average angular kicks from all misaligned magnets, we expect this misalignment model to serve as guidelines for resetting the strengths of corrector magnets. The third model for the Booster is a timestructured multiturn injection model. Microbunchinjection scenarios with different time structures are explored in the presence of longitudinal spacecharge force. Due to the radiofrequency (RF) bucket mismatch between the Booster and the 400MeV transferline, RFphase offsets can be parasitically introduced during the injection process. Using the microbunch multiturn injection, we carry out ESMEORBITcombined simulations. This combined simulation allows us to investigate realistic chargedensity distribution under full spacecharge effects. The growth rates of transverse emittances turned out to be 20 % in both planes. This microbunchinjection scenarios is also applicable to the future 8GeV Superconducting Linac Proton Driver and the upgraded Main Injector at Fermilab. In Part II, the feasibility of momentumstacking method of proton beams is investigated. When the Run2 collider program at Fermilab comes to an end around year 2009, the present antiproton source can be available for other purposes. One possible application is to convert the antiproton accumulator to a proton accumulator, so that the beam power from the Main Injector could be enhanced by a factor of four. Through adiabatic processes and optimized parameters of synchrotron motion, we demonstrate with an aid of the ESME code that up to four proton batches can be stacked in the momentum acceptance available for the Accumulator ring. This momentumstacking method is expected to be a part of Fermilab's SuperNuMI (SNuMI) project.},
doi = {10.2172/921701},
url = {https://www.osti.gov/biblio/921701},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2008},
month = {1}
}