2011 Particle Accelerator Conference - List of Authors (Rybarcyk, L.)

Paper

Title

Page

Space-charge Effects in H⁻ Low-energy Beam Transport of LANSCE

64

Y.K. Batygin, C. Pillai, L. Rybarcyk
LANL, Los Alamos, New Mexico, USA

The 750-keV low-energy beam transport of the Los Alamos Neutron Science Center (LANSCE) linac consists of two independent beam lines for simultaneous injection of H⁺ and H⁻ beams into the linear accelerator. While transport of the H⁺ beam is seriously affected by uncompensated space charge forces, the same effect for H⁻ is hidden by presence of multiple beam collimators and beam chopping. Recent results from beam development experiments indicate a significant influence of space charge on H⁻ beam dynamics in the low-energy beam transport. Measurements of beam emittance along beam transport show the formation of S-shaped filamentation in the particle distribution phase space, typical with the presence of non-linear space charge forces. Results are supported by particle tracking simulations with the PARMILA, BEAMPATH, and TRACE codes.

Slides MOOCS5 [6.304 MB]

WEP225

H-Mode Accelerating Structures with PMQ Focusing for Low-Beta Beams

1909

S.S. Kurennoy, J.F. O'Hara, E.R. Olivas, L. Rybarcyk
LANL, Los Alamos, New Mexico, USA

We report results of the project developing high-efficiency normal-conducting RF accelerating structures based on inter-digital H-mode (IH) cavities and the transverse beam focusing with permanent-magnet quadrupoles (PMQ), for beam velocities in the range of a few percent of the speed of light. The shunt impedance of IH-PMQ structures is 10^-20 times higher than that of a conventional drift-tube linac, while the transverse size is 4-5 times smaller. The H-PMQ accelerating structures following a short RFQ can be used both in the front end of ion linacs or in stand-alone applications. Results of the combined 3-D modeling – electromagnetic computations, beam-dynamics simulations with high currents, and thermal-stress analysis – for a full IH-PMQ accelerator tank are presented. The accelerating field profile in the tank is tuned to provide the best propagation of a 50-mA deuteron beam using coupled iterations of electromagnetic and beam-dynamics modeling. Multi-particle simulations with Parmela and CST Particle Studio have been used to confirm the design. Measurement results of a cold model of the IH-PMQ tank are in a good agreement with the calculations and will also be presented.

THOCN4

High-Power Options for LANSCE

2107

R.W. Garnett, E.J. Pitcher, D. Rees, L. Rybarcyk, T. Tajima
LANL, Los Alamos, New Mexico, USA

Funding: This work is supported by the U. S. Department of Energy Contract DE-AC52-06NA25396.
The LANSCE linear accelerator at Los Alamos National Laboratory has a long history of successful beam operations at 800 kW. We have recently studied options for restoration of high-power operations including schemes for increasing the performance to multi-MW levels. In this paper we will discuss the results of this study including the present limitations of the existing accelerating structures at LANSCE, and the high-voltage and RF systems that drive them. Several plausible options will be discussed and a preferred option will be presented that will enable the first in a new generation of scientific facilities for the materials community. The emphasis of this new facility is "Matter-Radiation Interactions in Extremes" (MaRIE) which will be used to discover and design the advanced materials needed to meet 21st century national security and energy security challenges.

Slides THOCN4 [2.903 MB]

Paper	Title	Page
MOOCS5	Space-charge Effects in H⁻ Low-energy Beam Transport of LANSCE	64
	Y.K. Batygin, C. Pillai, L. Rybarcyk LANL, Los Alamos, New Mexico, USA
	The 750-keV low-energy beam transport of the Los Alamos Neutron Science Center (LANSCE) linac consists of two independent beam lines for simultaneous injection of H⁺ and H⁻ beams into the linear accelerator. While transport of the H⁺ beam is seriously affected by uncompensated space charge forces, the same effect for H⁻ is hidden by presence of multiple beam collimators and beam chopping. Recent results from beam development experiments indicate a significant influence of space charge on H⁻ beam dynamics in the low-energy beam transport. Measurements of beam emittance along beam transport show the formation of S-shaped filamentation in the particle distribution phase space, typical with the presence of non-linear space charge forces. Results are supported by particle tracking simulations with the PARMILA, BEAMPATH, and TRACE codes.
	Slides MOOCS5 [6.304 MB]

WEP225	H-Mode Accelerating Structures with PMQ Focusing for Low-Beta Beams	1909
	S.S. Kurennoy, J.F. O'Hara, E.R. Olivas, L. Rybarcyk LANL, Los Alamos, New Mexico, USA
	We report results of the project developing high-efficiency normal-conducting RF accelerating structures based on inter-digital H-mode (IH) cavities and the transverse beam focusing with permanent-magnet quadrupoles (PMQ), for beam velocities in the range of a few percent of the speed of light. The shunt impedance of IH-PMQ structures is 10^-20 times higher than that of a conventional drift-tube linac, while the transverse size is 4-5 times smaller. The H-PMQ accelerating structures following a short RFQ can be used both in the front end of ion linacs or in stand-alone applications. Results of the combined 3-D modeling – electromagnetic computations, beam-dynamics simulations with high currents, and thermal-stress analysis – for a full IH-PMQ accelerator tank are presented. The accelerating field profile in the tank is tuned to provide the best propagation of a 50-mA deuteron beam using coupled iterations of electromagnetic and beam-dynamics modeling. Multi-particle simulations with Parmela and CST Particle Studio have been used to confirm the design. Measurement results of a cold model of the IH-PMQ tank are in a good agreement with the calculations and will also be presented.

THOCN4	High-Power Options for LANSCE	2107
	R.W. Garnett, E.J. Pitcher, D. Rees, L. Rybarcyk, T. Tajima LANL, Los Alamos, New Mexico, USA
	Funding: This work is supported by the U. S. Department of Energy Contract DE-AC52-06NA25396. The LANSCE linear accelerator at Los Alamos National Laboratory has a long history of successful beam operations at 800 kW. We have recently studied options for restoration of high-power operations including schemes for increasing the performance to multi-MW levels. In this paper we will discuss the results of this study including the present limitations of the existing accelerating structures at LANSCE, and the high-voltage and RF systems that drive them. Several plausible options will be discussed and a preferred option will be presented that will enable the first in a new generation of scientific facilities for the materials community. The emphasis of this new facility is "Matter-Radiation Interactions in Extremes" (MaRIE) which will be used to discover and design the advanced materials needed to meet 21st century national security and energy security challenges.
	Slides THOCN4 [2.903 MB]