IPAC2013 - List of Authors (Scheinker, A.)

Paper	Title	Page
MOPWA074	High Voltage Converter Modulator Optimization	852
	A. Scheinker LANL, Los Alamos, New Mexico, USA M.J. Bland University of Nottingham, Nottingham, United Kingdom
	High voltage converter modulators (HVCM) are at the forefront of long pulse high voltage (100kV) technology for Klystron voltage sources. We present results of digitally implementing an extremum seeking (ES) algorithm with which we optimized the rise time of the output voltage of a HVCM at the Los Alamos Neutron Science Center (LANSCE) HVCM test stand by iteratively, simultaneously tuning the first 8 switching edges of each of the three phase drive waveforms (24 variables total). We achieved a 50us rise time, which is reduction in half compared to the 100us currently achieved at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory. The ES algorithm is successful despite the noisy measurements and cost calculations, confirming the theoretical predictions that the algorithm is not affected by noise unless it both matches exactly the frequency components of the controller's specific perturbing frequencies and is of comparable size.

TUPWA064	Suppression of Halo Formation in FODO Focusing Channel with Nonlinear Focusing	1850
	Y.K. Batygin, A. Scheinker LANL, Los Alamos, New Mexico, USA
	Averaging method was applied to analyze focusing properties of a quadrupole FODO channel with inserted multipole lenses. General expression for averaged focusing potential is obtained as a function of position of multipole lenses with respect to FODO quadrupole lenses. Obtained results were applied to the problem of intense beam transport in combined FODO structure. Numerical and analytical treatments of high-brightness beam dynamics with suppressed space-charge induced halo formation are presented.

TUPWA068	Model Independent Beam Tuning	1862
	A. Scheinker LANL, Los Alamos, New Mexico, USA
	This work presents a new model independent feedback control scheme for optimization and tuning of particle accelerator components, with a simulation demonstrating the method on a low energy, space-charge dominated beam. The scheme presented here does not depend on an accurate model of the system it is stabilizing, and may even be unaware of its control input direction (such as having rotated quadrupole magnets and alignment errors) and this direction may change with time (thermal cycling and hysteresis). Stability properties are demonstrated both analytically and through a simulation in which the current settings of twenty two quadrupole magnets are simultaneously tuned through the transport section of the Los Alamos Linear Proton Accelerator. The controller is unaware of the complex nonlinear beam dynamics, with its only input being the surviving beam current readings along the transport region. Starting with all magnet settings at zero, in which case all of the beam is lost by the end of the transport, the feedback control tunes the magnets resulting in successful transport to the first drift tube linac section.

TUPWA069	Longitudinal Phase Space Dynamics with Novel Diagnostic Techniques at FACET	1865
	S.J. Gessner, E. Adli, F.-J. Decker, M.J. Hogan, T.O. Raubenheimer SLAC, Menlo Park, California, USA A. Scheinker LANL, Los Alamos, New Mexico, USA
	Funding: Work supported [optional: in part] by the U.S. Department of Energy under contract number DE-AC02-76SF00515. FACET produces high energy density electron beams for Plasma Wakefield Acceleration (PWFA) experiments. The high energy density beams are created by chirping the electron beam with accelerating sections and compressing the beam in magnetic chicanes. Precise control of the longitudinal beam profile is needed for the drive-witness bunch PWFA experiments currently underway at FACET. We discuss the simulations, controls, and diagnostics used to achieve FACET's unique longitudinal phase space.

Paper

Title

Page

High Voltage Converter Modulator Optimization

852

A. Scheinker
LANL, Los Alamos, New Mexico, USA
M.J. Bland
University of Nottingham, Nottingham, United Kingdom

High voltage converter modulators (HVCM) are at the forefront of long pulse high voltage (100kV) technology for Klystron voltage sources. We present results of digitally implementing an extremum seeking (ES) algorithm with which we optimized the rise time of the output voltage of a HVCM at the Los Alamos Neutron Science Center (LANSCE) HVCM test stand by iteratively, simultaneously tuning the first 8 switching edges of each of the three phase drive waveforms (24 variables total). We achieved a 50us rise time, which is reduction in half compared to the 100us currently achieved at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory. The ES algorithm is successful despite the noisy measurements and cost calculations, confirming the theoretical predictions that the algorithm is not affected by noise unless it both matches exactly the frequency components of the controller's specific perturbing frequencies and is of comparable size.

TUPWA064

Suppression of Halo Formation in FODO Focusing Channel with Nonlinear Focusing

1850

Y.K. Batygin, A. Scheinker
LANL, Los Alamos, New Mexico, USA

Averaging method was applied to analyze focusing properties of a quadrupole FODO channel with inserted multipole lenses. General expression for averaged focusing potential is obtained as a function of position of multipole lenses with respect to FODO quadrupole lenses. Obtained results were applied to the problem of intense beam transport in combined FODO structure. Numerical and analytical treatments of high-brightness beam dynamics with suppressed space-charge induced halo formation are presented.

TUPWA068

Model Independent Beam Tuning

1862

A. Scheinker
LANL, Los Alamos, New Mexico, USA

This work presents a new model independent feedback control scheme for optimization and tuning of particle accelerator components, with a simulation demonstrating the method on a low energy, space-charge dominated beam. The scheme presented here does not depend on an accurate model of the system it is stabilizing, and may even be unaware of its control input direction (such as having rotated quadrupole magnets and alignment errors) and this direction may change with time (thermal cycling and hysteresis). Stability properties are demonstrated both analytically and through a simulation in which the current settings of twenty two quadrupole magnets are simultaneously tuned through the transport section of the Los Alamos Linear Proton Accelerator. The controller is unaware of the complex nonlinear beam dynamics, with its only input being the surviving beam current readings along the transport region. Starting with all magnet settings at zero, in which case all of the beam is lost by the end of the transport, the feedback control tunes the magnets resulting in successful transport to the first drift tube linac section.

TUPWA069

Longitudinal Phase Space Dynamics with Novel Diagnostic Techniques at FACET

1865

S.J. Gessner, E. Adli, F.-J. Decker, M.J. Hogan, T.O. Raubenheimer
SLAC, Menlo Park, California, USA
A. Scheinker
LANL, Los Alamos, New Mexico, USA

Funding: Work supported [optional: in part] by the U.S. Department of Energy under contract number DE-AC02-76SF00515.
FACET produces high energy density electron beams for Plasma Wakefield Acceleration (PWFA) experiments. The high energy density beams are created by chirping the electron beam with accelerating sections and compressing the beam in magnetic chicanes. Precise control of the longitudinal beam profile is needed for the drive-witness bunch PWFA experiments currently underway at FACET. We discuss the simulations, controls, and diagnostics used to achieve FACET's unique longitudinal phase space.