IPAC2021 - List of Authors (Johnson, R.P.)

Paper	Title	Page
WEPAB328	Rapid Surface Microanalysis Using a Low Temperature Plasma	3440
	V.G. Dudnikov, M.A. Cummings, R.P. Johnson Muons, Inc, Illinois, USA
	There is a need for rapid, high-resolution (micron or sub-micron) scanning of surfaces of special nuclear materials (SNM) and surrogate materials to locate and identify regions of abnormalities. One technique that is commonly used to analyze the composition of solid surfaces and thin films is secondary-ion mass spectrometry (SIMS). SIMS devices are very complex and expensive. We propose to develop simpler, less expensive surface analysis devices, based on glow-discharge optical emission spectroscopy (GOES) that can provide excellent spatial resolution. Ions from a plasma discharge sputtered atoms from the surface and the discharge electrons effectively excite and ionize the sputtered atoms. GOES uses the light emitted by the excited particles for quantitative analysis. In the GOES device, the ion flux is extracted from the gas-discharge plasma and focused to a micron size on the sample, providing very local sputtering and local elemental analysis. The radiation from the sputtered atoms is passed through an optical fiber to an optical spectrometer and recorded. To register the distribution of elements over the sample, the sample is scanned electro-mechanically.
	Poster WEPAB328 [0.385 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB328
About •	paper received ※ 19 May 2021 paper accepted ※ 29 July 2021 issue date ※ 02 September 2021
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB121	Plasma Muon Beam Cooling for HEP	3999
	M.A. Cummings, R.J. Abrams, R.P. Johnson, S.A. Kahn, T.J. Roberts Muons, Inc, Illinois, USA V.S. Morozov, A.V. Sy JLab, Newport News, Virginia, USA K. Yonehara Fermilab, Batavia, Illinois, USA
	Ionization cooling has the potential to shrink the phase space of a muon beam by a factor of 10⁶ within the muons’ short lifetime (2.2 µs) because the collision frequency in a cooling medium is extremely high compared to conventional beam cooling methods. It has been realized that ionization cooling inherently produces a plasma of free electrons inside the absorber material, and this plasma can have an important effect on the muon beam. In particular, under the right circumstances, it can both improve the rate of cooling and reduce the equilibrium emittance of the beam. This has the potential to improve the performance of muon facilities based on muon cooling; in particular a future muon collider. We describe how this project will integrate Plasma muon beam cooling into both the basic Helical Cooling Channel (HCC) and extreme Parametric-resonance Ionization Cooling (PIC) techniques. This potentially whole new approach to muon cooling has exciting prospects for significantly reduced muon beam emittance.
	Poster THPAB121 [1.214 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB121
About •	paper received ※ 19 May 2021 paper accepted ※ 12 July 2021 issue date ※ 11 August 2021
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB336	Novel Magnetron Operation and Control Methods for Superconducting RF Accelerators	4442
	G.M. Kazakevich, R.P. Johnson Muons, Inc, Illinois, USA T.N. Khabiboulline, G.V. Romanov, V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	High power magnetrons designed and optimized for industrial heating, being injection-locked, have been suggested to power superconducting RF cavities for accelerators due to lower cost and higher efficiency. However, standard operation methods do not provide high efficiency with wideband control suppressing microphonics. We have developed and experimentally verified novel methods of operating and controlling the magnetron that provide stable RF generation with higher efficiency and lower noise than other RF sources. By our method the magnetrons operate with the anode voltage notably lower than the self-excitation threshold improving its performance. This is also a promising way to increase tube reliability and longevity. A magnetron operating with the anode voltage lower than the self-excitation threshold, in so-called stimulated coherent generation mode has special advantage for pulse operation with a gated injection-locking signal. This eliminates the need for expensive pulsed HV modulators and additionally increases the magnetron RF source efficiency due to absence of losses in HV modulators.
	Poster THPAB336 [0.960 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB336
About •	paper received ※ 15 May 2021 paper accepted ※ 08 July 2021 issue date ※ 22 August 2021
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB341	TiN Metalizing and Coating for Multi-Megawatt RF Vacuum Windows	4457
	M.L. Neubauer, A. Dudas, R.P. Johnson Muons, Inc, Illinois, USA
	Coatings on microwave windows and high-voltage ceramics are required to eliminate secondary electron emission (SEE), which initiates multipactoring discharge causing local heating and ceramic failures due to cracking and loss of vacuum. The region surrounding the triple junction (ceramic+metal+vacuum) is the primary source of free electrons and in microwave windows and high-voltage ceramics. This region is located at the metalizing and braze joint of the ceramic support structure making the vacuum seal. On very large microwave windows typically at low frequencies, this critical region is difficult to coat by the traditional techniques of sputter coating anti-multipactoring titanium nitride or other materials. The novel processes proposed here include a means for applying and controlling the thickness of titanium nitride both in the metallizing (controlling the source) and on the surface of the window, eliminating SEE and the multipactoring discharge.
	Poster THPAB341 [0.845 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB341
About •	paper received ※ 23 May 2021 paper accepted ※ 21 July 2021 issue date ※ 01 September 2021
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB364	Mu*STAR: A System to Consume Spent Nuclear Fuel While Economically Generating Nuclear Power	4499
	R.P. Johnson, R.J. Abrams, M.A. Cummings, S.A. Kahn, J.D. Lobo, T.J. Roberts Muons, Inc, Illinois, USA
	MuSTAR is a superconducting-accelerator driven, subcritical, molten-salt reactor designed to consume the spent nuclear fuel (SNF) from today’s commercial fleet of light water reactors. In the process of doing so it will: 1. generate electricity in a cost-competitive manner, 2. significantly reduce the waste-stream volume per Gigawatt-hour generated, 3. greatly reduce the radio-toxic lifetime of the waste stream. As many states and countries now prohibit licensing of new nuclear plants until a national strategy has been established for the long-term disposal of their nuclear waste, MuSTAR can be an important enabler for new nuclear facilities. This is especially important in the light of climate change, as nuclear energy is the only carbon-free technology for a base-load generation that is readily expandable.
	Poster THPAB364 [0.497 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB364
About •	paper received ※ 20 May 2021 paper accepted ※ 12 July 2021 issue date ※ 02 September 2021
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Rapid Surface Microanalysis Using a Low Temperature Plasma

3440

V.G. Dudnikov, M.A. Cummings, R.P. Johnson
Muons, Inc, Illinois, USA

There is a need for rapid, high-resolution (micron or sub-micron) scanning of surfaces of special nuclear materials (SNM) and surrogate materials to locate and identify regions of abnormalities. One technique that is commonly used to analyze the composition of solid surfaces and thin films is secondary-ion mass spectrometry (SIMS). SIMS devices are very complex and expensive. We propose to develop simpler, less expensive surface analysis devices, based on glow-discharge optical emission spectroscopy (GOES) that can provide excellent spatial resolution. Ions from a plasma discharge sputtered atoms from the surface and the discharge electrons effectively excite and ionize the sputtered atoms. GOES uses the light emitted by the excited particles for quantitative analysis. In the GOES device, the ion flux is extracted from the gas-discharge plasma and focused to a micron size on the sample, providing very local sputtering and local elemental analysis. The radiation from the sputtered atoms is passed through an optical fiber to an optical spectrometer and recorded. To register the distribution of elements over the sample, the sample is scanned electro-mechanically.

Poster WEPAB328 [0.385 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB328

About •

paper received ※ 19 May 2021 paper accepted ※ 29 July 2021 issue date ※ 02 September 2021

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB121

Plasma Muon Beam Cooling for HEP

3999

M.A. Cummings, R.J. Abrams, R.P. Johnson, S.A. Kahn, T.J. Roberts
Muons, Inc, Illinois, USA
V.S. Morozov, A.V. Sy
JLab, Newport News, Virginia, USA
K. Yonehara
Fermilab, Batavia, Illinois, USA

Ionization cooling has the potential to shrink the phase space of a muon beam by a factor of 10⁶ within the muons’ short lifetime (2.2 µs) because the collision frequency in a cooling medium is extremely high compared to conventional beam cooling methods. It has been realized that ionization cooling inherently produces a plasma of free electrons inside the absorber material, and this plasma can have an important effect on the muon beam. In particular, under the right circumstances, it can both improve the rate of cooling and reduce the equilibrium emittance of the beam. This has the potential to improve the performance of muon facilities based on muon cooling; in particular a future muon collider. We describe how this project will integrate Plasma muon beam cooling into both the basic Helical Cooling Channel (HCC) and extreme Parametric-resonance Ionization Cooling (PIC) techniques. This potentially whole new approach to muon cooling has exciting prospects for significantly reduced muon beam emittance.

Poster THPAB121 [1.214 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB121

About •

paper received ※ 19 May 2021 paper accepted ※ 12 July 2021 issue date ※ 11 August 2021

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB336

Novel Magnetron Operation and Control Methods for Superconducting RF Accelerators

4442

G.M. Kazakevich, R.P. Johnson
Muons, Inc, Illinois, USA
T.N. Khabiboulline, G.V. Romanov, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

High power magnetrons designed and optimized for industrial heating, being injection-locked, have been suggested to power superconducting RF cavities for accelerators due to lower cost and higher efficiency. However, standard operation methods do not provide high efficiency with wideband control suppressing microphonics. We have developed and experimentally verified novel methods of operating and controlling the magnetron that provide stable RF generation with higher efficiency and lower noise than other RF sources. By our method the magnetrons operate with the anode voltage notably lower than the self-excitation threshold improving its performance. This is also a promising way to increase tube reliability and longevity. A magnetron operating with the anode voltage lower than the self-excitation threshold, in so-called stimulated coherent generation mode has special advantage for pulse operation with a gated injection-locking signal. This eliminates the need for expensive pulsed HV modulators and additionally increases the magnetron RF source efficiency due to absence of losses in HV modulators.

Poster THPAB336 [0.960 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB336

About •

paper received ※ 15 May 2021 paper accepted ※ 08 July 2021 issue date ※ 22 August 2021

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB341

TiN Metalizing and Coating for Multi-Megawatt RF Vacuum Windows

4457

M.L. Neubauer, A. Dudas, R.P. Johnson
Muons, Inc, Illinois, USA

Coatings on microwave windows and high-voltage ceramics are required to eliminate secondary electron emission (SEE), which initiates multipactoring discharge causing local heating and ceramic failures due to cracking and loss of vacuum. The region surrounding the triple junction (ceramic+metal+vacuum) is the primary source of free electrons and in microwave windows and high-voltage ceramics. This region is located at the metalizing and braze joint of the ceramic support structure making the vacuum seal. On very large microwave windows typically at low frequencies, this critical region is difficult to coat by the traditional techniques of sputter coating anti-multipactoring titanium nitride or other materials. The novel processes proposed here include a means for applying and controlling the thickness of titanium nitride both in the metallizing (controlling the source) and on the surface of the window, eliminating SEE and the multipactoring discharge.

Poster THPAB341 [0.845 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB341

About •

paper received ※ 23 May 2021 paper accepted ※ 21 July 2021 issue date ※ 01 September 2021

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB364

Mu*STAR: A System to Consume Spent Nuclear Fuel While Economically Generating Nuclear Power

4499

R.P. Johnson, R.J. Abrams, M.A. Cummings, S.A. Kahn, J.D. Lobo, T.J. Roberts
Muons, Inc, Illinois, USA

Mu*STAR is a superconducting-accelerator driven, subcritical, molten-salt reactor designed to consume the spent nuclear fuel (SNF) from today’s commercial fleet of light water reactors. In the process of doing so it will: 1. generate electricity in a cost-competitive manner, 2. significantly reduce the waste-stream volume per Gigawatt-hour generated, 3. greatly reduce the radio-toxic lifetime of the waste stream. As many states and countries now prohibit licensing of new nuclear plants until a national strategy has been established for the long-term disposal of their nuclear waste, Mu*STAR can be an important enabler for new nuclear facilities. This is especially important in the light of climate change, as nuclear energy is the only carbon-free technology for a base-load generation that is readily expandable.

Poster THPAB364 [0.497 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB364

About •

paper received ※ 20 May 2021 paper accepted ※ 12 July 2021 issue date ※ 02 September 2021

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)