PAC2013 - List of Authors (Flanagan, G.)

Paper	Title	Page
WEPMA12	Investigation of Breakdown Induced Surface Damage on 805 MHz Pill Box Cavity Interior Surfaces	1007
	M.R. Jana, M. Chung, M.A. Leonova, A. Moretti, A.V. Tollestrup, K. Yonehara Fermilab, Batavia, USA D.L. Bowring LBNL, Berkeley, California, USA G. Flanagan Muons, Inc, Illinois, USA B.T. Freemire, Y. Torun IIT, Chicago, Illinois, USA
	The MuCool Test Area (MTA) at Fermilab is a facility to develop the technology required for ionization cooling for a future Muon Collider and/or Neutrino Factory. As part of this research program, we have tested an 805 MHz Pill Box RF cavity in multi-Tesla magnetic field to study the effects of the static magnetic field on the cavity operation. This study gives useful information on field emitters in the cavity, dark current, surface conditioning, breakdown mechanism and material properties of the cavity. All these factors determine the maximum accelerating gradient in the cavity. This paper discusses the image processing technique for the quantitative estimation of spark damage spot distribution on the Pill Box RF cavity interior surfaces. The distribution is compared with the electric field distribution predicted by computer code calculation. The local spark density is proportional to probability of surface breakdown and shows a power law dependence on the maximum electric field (E). This E dependence is consistent with dark current calculated from Fowler-Nordheim equation.

THPBA22	Helical Muon Beam Cooling Channel Engineering Design	1274
	G. Flanagan, R.P. Johnson, S.A. Kahn, M.L. Neubauer Muons, Inc, Illinois, USA N. Andreev, R. Bossert, S. Krave, M.L. Lopes, J.C. Tompkins, K. Yonehara Fermilab, Batavia, USA F. Marhauser MuPlus, Inc., Newport News, USA
	Funding: DOE STTR Grant DE-SC0006266 The Helical Cooling Channel (HCC), a novel technique for six-dimensional (6D) ionization cooling of muon beams, has shown considerable promise based on analytic and simulation studies. However, the implementation of this revolutionary method of muon cooling requires new techniques for the integration of hydrogen-pressurized, high-power RF cavities into the low-temperature superconducting magnets of the HCC. We discuss progress and plans toward the critical path technology demonstrations of dielectric loaded 805 MHz RF cavities and 10 T Nb3Sn based Helical Solenoid magnet. Additionally we discuss integration challenges.

THPBA23	Disposition of Weapons-Grade Plutonium with GEM*STAR	1277
	R.P. Johnson, G. Flanagan, F. Marhauser Muons, Inc, Illinois, USA C. Bowman, R.B. Vogelaar ADNA, Los Alamos, New Mexico, USA
	The 75,000 tons of US stored spent nuclear fuel (SNF) from conventional nuclear reactors is a resource that could provide 125 years of all US electrical power. Or it could also provide a great amount of process heat for many applications like producing green diesel fuel from natural gas and renewable carbon. An accelerator system like the SNS at ORNL can provide neutrons to convert SNF into fissile isotopes to provide high temperature heat using technology developed at the ORNL Molten Salt Reactor Experiment. In the GEMSTAR [1] accelerator-driven subcritical reactor that we wish to build, the accelerator allows subcritical operation (no Chernobyls), the molten salt fuel allows volatiles to be continuously removed (no Fukushimas), and the SNF does not need to be enriched or reprocessed (to minimize weapons proliferation concerns). The same GEMSTAR accelerator-driven reactor we plan to use for SNF burning can also be used to burn weapons-grade Plutonium to extract energy and make remnants permanently unusable for weapons. [1] Charles D. Bowman, R. Bruce Vogelaar, et al., “GEM*STAR: The Alternative Reactor Technology Comprising Graphite, Molten Salt, and Accelerators,” Handbook of Nuclear Engineering, Springer (2010).

THPBA24	A Dipole Magnet for the FRIB High Radiation Environment Nuclear Fragment Separator	1280
	S.A. Kahn, A. Dudas, G. Flanagan, J.H. Nipper Muons, Inc, Illinois, USA M. Anerella, R.C. Gupta, J. Schmalzle BNL, Upton, Long Island, New York, USA
	Funding: U.S. DOE grants DE-SC-0006273 and DE-AC02-98CH10886 Magnets in the fragment separator region of the Facility for Rare Isotope Beams (FRIB) would be subjected to extremely high radiation and heat loads. Critical elements of FRIB are the dipole magnets which select the desired isotopes. Since conventional NiTi and Nb3Sn superconductors must operate at ~4.5 K, the removal of the high heat load generated in these magnets with these superconductors would be difficult. The coils for these magnets must accommodate the large curvature from the 30° bend that the magnets subtend. High temperature superconductors (HTS) have been shown to be radiation resistant and can operate in the 40 K temperature range where heat removal is an order of magnitude more efficient than at 4.5 K. This paper will describe the magnetic and preliminary engineering design of these magnets.

THPBA26	Elliptical Muon Helical Cooling Channel Coils	1286
	S.A. Kahn, G. Flanagan Muons, Inc, Illinois, USA M.L. Lopes, K. Yonehara Fermilab, Batavia, USA
	Funding: U.S. DOE Grant Number DE-SC0006266 A helical cooling channel (HCC) consisting of a pressurized gas absorber imbedded in a magnetic channel that provides solenoid, helical dipole and helical quadrupole fields has shown considerable promise in providing six-dimensional phase space reduction for muon beams. The most effective approach to implementing the desired magnetic field is a helical solenoid (HS) channel composed of short solenoid coils arranged in a helical pattern. The HS channel along with an external solenoid allows the Bz and Bphi components along the reference orbit to be set to any desired values. To set dBphi/dr to the desired value for optimum focusing requires an additional variable. We shall show that using elliptical shaped coils in the HS channel allows the flexibility to achieve the desired dBphi/dr on orbit without significant change to Bz and Bphi.

Paper

Title

Page

Investigation of Breakdown Induced Surface Damage on 805 MHz Pill Box Cavity Interior Surfaces

1007

M.R. Jana, M. Chung, M.A. Leonova, A. Moretti, A.V. Tollestrup, K. Yonehara
Fermilab, Batavia, USA
D.L. Bowring
LBNL, Berkeley, California, USA
G. Flanagan
Muons, Inc, Illinois, USA
B.T. Freemire, Y. Torun
IIT, Chicago, Illinois, USA

The MuCool Test Area (MTA) at Fermilab is a facility to develop the technology required for ionization cooling for a future Muon Collider and/or Neutrino Factory. As part of this research program, we have tested an 805 MHz Pill Box RF cavity in multi-Tesla magnetic field to study the effects of the static magnetic field on the cavity operation. This study gives useful information on field emitters in the cavity, dark current, surface conditioning, breakdown mechanism and material properties of the cavity. All these factors determine the maximum accelerating gradient in the cavity. This paper discusses the image processing technique for the quantitative estimation of spark damage spot distribution on the Pill Box RF cavity interior surfaces. The distribution is compared with the electric field distribution predicted by computer code calculation. The local spark density is proportional to probability of surface breakdown and shows a power law dependence on the maximum electric field (E). This E dependence is consistent with dark current calculated from Fowler-Nordheim equation.

THPBA22

Helical Muon Beam Cooling Channel Engineering Design

1274

G. Flanagan, R.P. Johnson, S.A. Kahn, M.L. Neubauer
Muons, Inc, Illinois, USA
N. Andreev, R. Bossert, S. Krave, M.L. Lopes, J.C. Tompkins, K. Yonehara
Fermilab, Batavia, USA
F. Marhauser
MuPlus, Inc., Newport News, USA

Funding: DOE STTR Grant DE-SC0006266
The Helical Cooling Channel (HCC), a novel technique for six-dimensional (6D) ionization cooling of muon beams, has shown considerable promise based on analytic and simulation studies. However, the implementation of this revolutionary method of muon cooling requires new techniques for the integration of hydrogen-pressurized, high-power RF cavities into the low-temperature superconducting magnets of the HCC. We discuss progress and plans toward the critical path technology demonstrations of dielectric loaded 805 MHz RF cavities and 10 T Nb3Sn based Helical Solenoid magnet. Additionally we discuss integration challenges.

THPBA23

Disposition of Weapons-Grade Plutonium with GEM*STAR

1277

R.P. Johnson, G. Flanagan, F. Marhauser
Muons, Inc, Illinois, USA
C. Bowman, R.B. Vogelaar
ADNA, Los Alamos, New Mexico, USA

The 75,000 tons of US stored spent nuclear fuel (SNF) from conventional nuclear reactors is a resource that could provide 125 years of all US electrical power. Or it could also provide a great amount of process heat for many applications like producing green diesel fuel from natural gas and renewable carbon. An accelerator system like the SNS at ORNL can provide neutrons to convert SNF into fissile isotopes to provide high temperature heat using technology developed at the ORNL Molten Salt Reactor Experiment. In the GEM*STAR [1] accelerator-driven subcritical reactor that we wish to build, the accelerator allows subcritical operation (no Chernobyls), the molten salt fuel allows volatiles to be continuously removed (no Fukushimas), and the SNF does not need to be enriched or reprocessed (to minimize weapons proliferation concerns). The same GEM*STAR accelerator-driven reactor we plan to use for SNF burning can also be used to burn weapons-grade Plutonium to extract energy and make remnants permanently unusable for weapons.
[1] Charles D. Bowman, R. Bruce Vogelaar, et al., “GEM*STAR: The Alternative Reactor Technology Comprising Graphite, Molten Salt, and Accelerators,” Handbook of Nuclear Engineering, Springer (2010).

THPBA24

A Dipole Magnet for the FRIB High Radiation Environment Nuclear Fragment Separator

1280

S.A. Kahn, A. Dudas, G. Flanagan, J.H. Nipper
Muons, Inc, Illinois, USA
M. Anerella, R.C. Gupta, J. Schmalzle
BNL, Upton, Long Island, New York, USA

Funding: U.S. DOE grants DE-SC-0006273 and DE-AC02-98CH10886
Magnets in the fragment separator region of the Facility for Rare Isotope Beams (FRIB) would be subjected to extremely high radiation and heat loads. Critical elements of FRIB are the dipole magnets which select the desired isotopes. Since conventional NiTi and Nb3Sn superconductors must operate at ~4.5 K, the removal of the high heat load generated in these magnets with these superconductors would be difficult. The coils for these magnets must accommodate the large curvature from the 30° bend that the magnets subtend. High temperature superconductors (HTS) have been shown to be radiation resistant and can operate in the 40 K temperature range where heat removal is an order of magnitude more efficient than at 4.5 K. This paper will describe the magnetic and preliminary engineering design of these magnets.

THPBA26

Elliptical Muon Helical Cooling Channel Coils

1286

S.A. Kahn, G. Flanagan
Muons, Inc, Illinois, USA
M.L. Lopes, K. Yonehara
Fermilab, Batavia, USA

Funding: U.S. DOE Grant Number DE-SC0006266
A helical cooling channel (HCC) consisting of a pressurized gas absorber imbedded in a magnetic channel that provides solenoid, helical dipole and helical quadrupole fields has shown considerable promise in providing six-dimensional phase space reduction for muon beams. The most effective approach to implementing the desired magnetic field is a helical solenoid (HS) channel composed of short solenoid coils arranged in a helical pattern. The HS channel along with an external solenoid allows the Bz and Bphi components along the reference orbit to be set to any desired values. To set dBphi/dr to the desired value for optimum focusing requires an additional variable. We shall show that using elliptical shaped coils in the HS channel allows the flexibility to achieve the desired dBphi/dr on orbit without significant change to Bz and Bphi.