PAC2013 - List of Authors (Johnson, R.P.)

Paper

Title

Page

Beam Brightness Booster with Ionization Cooling of Superintense Circulating Beams

123

V.G. Dudnikov, C.M. Ankenbrandt, R.P. Johnson, L.G. Vorobiev
Muons, Inc, Illinois, USA

An increase of intensity and brightness of proton beam by means of charge exchange injection and devices developed for this experiment are considered. First observation of e-p instability, explanation and damping by feed back are discussed. Discovery of “cesiation effect” leading to multiple increase of negative ion emission from gas discharges and development of surface-plasma sources for intense high brightness negative ion beams production are considered. By these developments were prepared a possibility for production of stable “superintense” circulating beam with intensity and brightness fare above space charge limit. A beam brightness booster (BBB) for significant increase of accumulated beam brightness is discussed. New opportunity for simplification of the superintense beam production is promised by developing of nonlinear close to integrable focusing system with broad spread of betatron tune and the broad bend feed back system for e-p instability suppression. Effects of ionization cooling can be used for suppression of the beam particle scattering in the stripping target

TUODA1

High Pressure Gas-Filled RF Cavities for Use in a Muon Cooling Channel

419

B.T. Freemire, P.M. Hanlet, Y. Torun
IIT, Chicago, Illinois, USA
M. Chung, M.R. Jana, M.A. Leonova, A. Moretti, T.A. Schwarz, A.V. Tollestrup, Y. Torun, K. Yonehara
Fermilab, Batavia, USA
M.G. Collura
Politecnico di Torino, Torino, Italy
R.P. Johnson
Muons, Inc, Illinois, USA

A high pressure hydrogen gas-filled RF (HPRF) cavity can operate in the multi-Tesla magnetic fields required for a muon accelerator cooling channel. A beam test was performed at the Fermilab MuCool Test Area by sending a 400 MeV proton beam through an 805 MHz cavity and quantifying the effects of the resulting plasma within the cavity. The resulting energy loss per electron-ion pair produced has been measured at 10^-18 to 10^-16 J every RF cycle. Doping the hydrogen gas with oxygen greatly decreases the lifetime of an electron, thereby improving the performance of the HPRF cavity. Electron lifetimes as short as 1 ns have been measured. The recombination rate of positive and negative ions in the cavity has been measured on the order of 10^-8 cm³/s. Extrapolation in both gas pressure and beam intensity are required to obtain Muon Collider parameters, however the results indicate HPRF cavities can be used in a muon accelerator cooling channel.

Slides TUODA1 [12.191 MB]

TUPSM22

Improving Efficiency of Ions Production in Ion Source with Saddle Antenna

682

V.G. Dudnikov, R.P. Johnson
Muons, Inc, Illinois, USA
T.R. Pennisi, C. Piller, M. Santana, M.P. Stockli, R.F. Welton
ORNL, Oak Ridge, Tennessee, USA
M.W. Turvey
University of Florida, Gainesville, Florida, USA

Funding: Work supported in part by US DOE Contract DE-AC05-00OR22725 and by STTR grant DE-SC0002690.
Extraction of negative ions from RF surface plasma source (SPS) with saddle antenna radio frequency (SA RF) discharge is considered. Several versions of new plasma generators with different antennas and magnetic field configurations were tested in the SNS small Test Stand. The efficiency of positive ion generation in plasma has been improved up to ~90 mA/cm² per 1 kW of RF power at 13.56 MHz. For first cesiation was used a heating of the cesium chromate cartridges by CW RF discharge. A small oven for cesium compounds and alloys decomposition by heating was developed and tested. After cesiation a current of negative ions to the collector was increased from 0.5 mA to 10 mA with RF power ~ 1.5 kW in the plasma and longitudinal magnetic field Bl~250 Gauss. With increase of a longitudinal magnetic field the collector current can be increased up to 7 times. A stable long time generation of H⁻ beam without degradation was demonstrated in RF discharge with AlN discharge chamber.

WEPHO15

Modeling of Magnetron Transmitter for the Project X CW 1 GEV Linac

966

G.M. Kazakevich, R.P. Johnson
Muons, Inc, Illinois, USA
B. Chase, R.J. Pasquinelli, V.P. Yakovlev
Fermilab, Batavia, USA

A 650 MHz 50 kW transmitter with a wide-band control in phase and power, based on injection-locked CW magnetrons, intended to drive individually Superconducting RF (SRF) cavities has been proposed for the Project X CW 1 GeV linac. Utilization of the magnetron RF sources for the intensity-frontier project will save a significant capital cost in comparison with traditional RF sources based on klystrons, Inductive Output Tubes (IOTs), solid-state amplifiers. The transmitter setup has been modelled experimentally and by simulation using 2.45 GHz CW magnetrons with output power up to 1 kW. The measurements and simulations performed with the injection-locked magnetrons demonstrated capability of the proposed transmitter concept to power individually the superconducting cavities suppressing parasitic modulation of the accelerating field caused by mechanical oscillation (microphonics and oscillations resulted from Lorentz-force), beam loading, dynamic tuning errors, and other low-frequency disturbances of the magnetron performance. Results of the experimental and theoretical modelling are analysed and discussed in this paper.

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).

THPHO19

A Charge Separation Study to Enable the Design of a Complete Muon Cooling Channel

1343

C.Y. Yoshikawa, C.M. Ankenbrandt, R.P. Johnson
Muons, Inc, Illinois, USA
Y.S. Derbenev, V.S. Morozov
JLAB, Newport News, Virginia, USA
D.V. Neuffer, K. Yonehara
Fermilab, Batavia, USA

Funding: Work supported in part by DOE STTR grant DE-SC0007634
The most promising designs for 6D muon cooling channels operate on a specific sign of electric charge. In particular, the Helical Cooling Channel (HCC) and Rectilinear RFOFO designs are the leading candidates to become the baseline 6D cooling channel in the Muon Accelerator Program (MAP). Time constraints prevented the design of a realistic charge separator, so a simplified study was performed to emulate the effects of charge separation on muons exiting the front end of a muon collider. The output of the study provides particle distributions that the competing designs will use as input into their cooling channels. We report here on the study of the charge separator that created the simulated particles.

Paper	Title	Page
MOPAC26	Beam Brightness Booster with Ionization Cooling of Superintense Circulating Beams	123
	V.G. Dudnikov, C.M. Ankenbrandt, R.P. Johnson, L.G. Vorobiev Muons, Inc, Illinois, USA
	An increase of intensity and brightness of proton beam by means of charge exchange injection and devices developed for this experiment are considered. First observation of e-p instability, explanation and damping by feed back are discussed. Discovery of “cesiation effect” leading to multiple increase of negative ion emission from gas discharges and development of surface-plasma sources for intense high brightness negative ion beams production are considered. By these developments were prepared a possibility for production of stable “superintense” circulating beam with intensity and brightness fare above space charge limit. A beam brightness booster (BBB) for significant increase of accumulated beam brightness is discussed. New opportunity for simplification of the superintense beam production is promised by developing of nonlinear close to integrable focusing system with broad spread of betatron tune and the broad bend feed back system for e-p instability suppression. Effects of ionization cooling can be used for suppression of the beam particle scattering in the stripping target

TUODA1	High Pressure Gas-Filled RF Cavities for Use in a Muon Cooling Channel	419
	B.T. Freemire, P.M. Hanlet, Y. Torun IIT, Chicago, Illinois, USA M. Chung, M.R. Jana, M.A. Leonova, A. Moretti, T.A. Schwarz, A.V. Tollestrup, Y. Torun, K. Yonehara Fermilab, Batavia, USA M.G. Collura Politecnico di Torino, Torino, Italy R.P. Johnson Muons, Inc, Illinois, USA
	A high pressure hydrogen gas-filled RF (HPRF) cavity can operate in the multi-Tesla magnetic fields required for a muon accelerator cooling channel. A beam test was performed at the Fermilab MuCool Test Area by sending a 400 MeV proton beam through an 805 MHz cavity and quantifying the effects of the resulting plasma within the cavity. The resulting energy loss per electron-ion pair produced has been measured at 10^-18 to 10^-16 J every RF cycle. Doping the hydrogen gas with oxygen greatly decreases the lifetime of an electron, thereby improving the performance of the HPRF cavity. Electron lifetimes as short as 1 ns have been measured. The recombination rate of positive and negative ions in the cavity has been measured on the order of 10^-8 cm³/s. Extrapolation in both gas pressure and beam intensity are required to obtain Muon Collider parameters, however the results indicate HPRF cavities can be used in a muon accelerator cooling channel.
	Slides TUODA1 [12.191 MB]

TUPSM22	Improving Efficiency of Ions Production in Ion Source with Saddle Antenna	682
	V.G. Dudnikov, R.P. Johnson Muons, Inc, Illinois, USA T.R. Pennisi, C. Piller, M. Santana, M.P. Stockli, R.F. Welton ORNL, Oak Ridge, Tennessee, USA M.W. Turvey University of Florida, Gainesville, Florida, USA
	Funding: Work supported in part by US DOE Contract DE-AC05-00OR22725 and by STTR grant DE-SC0002690. Extraction of negative ions from RF surface plasma source (SPS) with saddle antenna radio frequency (SA RF) discharge is considered. Several versions of new plasma generators with different antennas and magnetic field configurations were tested in the SNS small Test Stand. The efficiency of positive ion generation in plasma has been improved up to ~90 mA/cm² per 1 kW of RF power at 13.56 MHz. For first cesiation was used a heating of the cesium chromate cartridges by CW RF discharge. A small oven for cesium compounds and alloys decomposition by heating was developed and tested. After cesiation a current of negative ions to the collector was increased from 0.5 mA to 10 mA with RF power ~ 1.5 kW in the plasma and longitudinal magnetic field Bl~250 Gauss. With increase of a longitudinal magnetic field the collector current can be increased up to 7 times. A stable long time generation of H⁻ beam without degradation was demonstrated in RF discharge with AlN discharge chamber.

WEPHO15	Modeling of Magnetron Transmitter for the Project X CW 1 GEV Linac	966
	G.M. Kazakevich, R.P. Johnson Muons, Inc, Illinois, USA B. Chase, R.J. Pasquinelli, V.P. Yakovlev Fermilab, Batavia, USA
	A 650 MHz 50 kW transmitter with a wide-band control in phase and power, based on injection-locked CW magnetrons, intended to drive individually Superconducting RF (SRF) cavities has been proposed for the Project X CW 1 GeV linac. Utilization of the magnetron RF sources for the intensity-frontier project will save a significant capital cost in comparison with traditional RF sources based on klystrons, Inductive Output Tubes (IOTs), solid-state amplifiers. The transmitter setup has been modelled experimentally and by simulation using 2.45 GHz CW magnetrons with output power up to 1 kW. The measurements and simulations performed with the injection-locked magnetrons demonstrated capability of the proposed transmitter concept to power individually the superconducting cavities suppressing parasitic modulation of the accelerating field caused by mechanical oscillation (microphonics and oscillations resulted from Lorentz-force), beam loading, dynamic tuning errors, and other low-frequency disturbances of the magnetron performance. Results of the experimental and theoretical modelling are analysed and discussed in this paper.

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).

THPHO19	A Charge Separation Study to Enable the Design of a Complete Muon Cooling Channel	1343
	C.Y. Yoshikawa, C.M. Ankenbrandt, R.P. Johnson Muons, Inc, Illinois, USA Y.S. Derbenev, V.S. Morozov JLAB, Newport News, Virginia, USA D.V. Neuffer, K. Yonehara Fermilab, Batavia, USA
	Funding: Work supported in part by DOE STTR grant DE-SC0007634 The most promising designs for 6D muon cooling channels operate on a specific sign of electric charge. In particular, the Helical Cooling Channel (HCC) and Rectilinear RFOFO designs are the leading candidates to become the baseline 6D cooling channel in the Muon Accelerator Program (MAP). Time constraints prevented the design of a realistic charge separator, so a simplified study was performed to emulate the effects of charge separation on muons exiting the front end of a muon collider. The output of the study provides particle distributions that the competing designs will use as input into their cooling channels. We report here on the study of the charge separator that created the simulated particles.