IPAC2019 - List of Authors (Marsh, R.A.)

Paper	Title	Page
TUPMP033	Design of the Neutron Imaging Differential Pumping Line at LLNL	1312
	J.A. Caggiano, D. Castronovo, P. Fitsos, D.J. Gibson, J. Hall, M.S. Johnson, R.A. Marsh, B. Rusnak LLNL, Livermore, California, USA
	Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. The neutron imaging system at LLNL is a radiographic capability for imaging objects with fast, quasi-monoenergetic neutrons at ≤1mm spatial resolution. The neutron production source is a deuteron beam (4 or 7 MeV) incident upon a rotating, high-pressure, windowless, pure-deuterium gas target. The windowless nature of the target combined with the high pressure leads to significant gas leakage upstream of the neutron production target. This leakage degrades the imaging quality by (1) increasing the depth-of-field blurring and (2) increasing the beam diameter and divergence in the transverse direction via angular straggling in the residual gas. To mitigate these effects, and guided by bench tests and simulations, we designed a differential pumping line (DPL) to ensure the highest quality imaging system. The system consists of three primary stages (chambers), each separated by carefully shaped apertures. These apertures can be long and thin with low-angle tapers due to the high quality of the beam optics (convergence at the target < 5mrad) and low emittance of the beam (~5 pi mm-mrad). The primary cascaded roots pumps are sized to remove >99% of the incoming mass flow in each stage, ensuring that by the third stage furthest from the target, turbomolecular pumps are able to operate in a nominal ~mTorr range. We anticipate full system testing with helium in mid 2019.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP033
About •	paper received ※ 30 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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WEPGW120	Fluorescence-Based Imaging Diagnostic for High Average Power Deuteron Beam	2777
WEPGW119	use link to see paper's listing under its alternate paper code
	R.A. Marsh, S.G. Anderson, D.J. Gibson, J. Hall, B. Rusnak LLNL, Livermore, California, USA
	Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Lawrence Livermore National Laboratory is developing an intense, high-brightness fast neutron source to create sub-millimeter-scale resolution neutron radiographs and imag-es. An intense source (10¹¹ n/s/sr at 0 degrees) of fast neutrons (10 MeV) will be produced using a pulsed 7 MeV, 300μAmp average-current commercial deuteron accelerator producing a small (1.5 mm diameter) beam spot size to achieve high resolution. The high average power beam is a challenge for diagnostics, and a precise full power emittance measurement is critical to benchmark the system performance. A fluorescence-based beam profiling diagnostic has been selected, and this paper presents the design for the system including chamber layout, light yield calculations, and imaging system details.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW120
About •	paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Design of the Neutron Imaging Differential Pumping Line at LLNL

1312

J.A. Caggiano, D. Castronovo, P. Fitsos, D.J. Gibson, J. Hall, M.S. Johnson, R.A. Marsh, B. Rusnak
LLNL, Livermore, California, USA

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
The neutron imaging system at LLNL is a radiographic capability for imaging objects with fast, quasi-monoenergetic neutrons at ≤1mm spatial resolution. The neutron production source is a deuteron beam (4 or 7 MeV) incident upon a rotating, high-pressure, windowless, pure-deuterium gas target. The windowless nature of the target combined with the high pressure leads to significant gas leakage upstream of the neutron production target. This leakage degrades the imaging quality by (1) increasing the depth-of-field blurring and (2) increasing the beam diameter and divergence in the transverse direction via angular straggling in the residual gas. To mitigate these effects, and guided by bench tests and simulations, we designed a differential pumping line (DPL) to ensure the highest quality imaging system. The system consists of three primary stages (chambers), each separated by carefully shaped apertures. These apertures can be long and thin with low-angle tapers due to the high quality of the beam optics (convergence at the target < 5mrad) and low emittance of the beam (~5 pi mm-mrad). The primary cascaded roots pumps are sized to remove >99% of the incoming mass flow in each stage, ensuring that by the third stage furthest from the target, turbomolecular pumps are able to operate in a nominal ~mTorr range. We anticipate full system testing with helium in mid 2019.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP033

About •

paper received ※ 30 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

Export •

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

WEPGW120

Fluorescence-Based Imaging Diagnostic for High Average Power Deuteron Beam

2777

WEPGW119

use link to see paper's listing under its alternate paper code

R.A. Marsh, S.G. Anderson, D.J. Gibson, J. Hall, B. Rusnak
LLNL, Livermore, California, USA

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Lawrence Livermore National Laboratory is developing an intense, high-brightness fast neutron source to create sub-millimeter-scale resolution neutron radiographs and imag-es. An intense source (10¹¹ n/s/sr at 0 degrees) of fast neutrons (10 MeV) will be produced using a pulsed 7 MeV, 300μAmp average-current commercial deuteron accelerator producing a small (1.5 mm diameter) beam spot size to achieve high resolution. The high average power beam is a challenge for diagnostics, and a precise full power emittance measurement is critical to benchmark the system performance. A fluorescence-based beam profiling diagnostic has been selected, and this paper presents the design for the system including chamber layout, light yield calculations, and imaging system details.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW120

About •

paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

Export •

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