ECRIS2020 - List of Authors (Lund, S.M.)

Paper	Title	Page
TUZZO05	Multi-Species Child-Langmuir Law with Application to ECR Ion Sources	106
	C.Y. Wong ORNL, Oak Ridge, Tennessee, USA S.M. Lund FRIB, East Lansing, Michigan, USA
	We generalize the classical single-species Child-Langmuir Law to analyze multi-species beams from ECR ion sources. The formulation assumes the relative weight of each species in the extracted beam is known. We apply the results to charge state distribution data from Artemis- and Venus-type sources at the NSCL and LBNL respectively. The total measured beam current is close to the maximum current predicted by the multi-species Child Langmuir law in each case, which indicates that beam extraction occurs close to space-charge-limited flow conditions. Prospects for application of the results and further studies on the topic are outlined.
	Slides TUZZO05 [0.508 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2020-TUZZO05
About •	Received ※ 28 September 2020 — Revised ※ 28 December 2020 — Accepted ※ 16 January 2021 — Issue date ※ 18 May 2021
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUZZO06	Beams with Three-Fold Rotational Symmetry: A Theoretical Study	110
	C.Y. Wong ORNL, Oak Ridge, Tennessee, USA S.M. Lund FRIB, East Lansing, Michigan, USA
	Beams from ECR ion sources have 3-fold transverse rotational symmetry induced by the ECR sextupole. The symmetry imposes equality constraints among transverse beam moments, which can be derived using a theoretical framework we developed. Since the constraints are solely a consequence of the rotational symmetry of external fields, they hold for a multi-species beam with arbitrary composition and space charge intensity. These constraints provide a new tool to analyze phase space properties of ECR beams and their impact on low-energy transport. We prove that, regardless of their triangulated spatial density profile, beams with 3-fold rotational symmetry have the same RMS emittance and Twiss parameters along any transverse direction. These counter-intuitive results are applied to the FRIB Front End to show how symmetry arguments challenge long-standing assumptions and bring clarity to the beam dynamics.
	Slides TUZZO06 [0.846 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2020-TUZZO06
About •	Received ※ 28 September 2020 — Revised ※ 14 May 2021 — Accepted ※ 18 May 2021 — Issue date ※ 03 November 2021
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Multi-Species Child-Langmuir Law with Application to ECR Ion Sources

106

C.Y. Wong
ORNL, Oak Ridge, Tennessee, USA
S.M. Lund
FRIB, East Lansing, Michigan, USA

We generalize the classical single-species Child-Langmuir Law to analyze multi-species beams from ECR ion sources. The formulation assumes the relative weight of each species in the extracted beam is known. We apply the results to charge state distribution data from Artemis- and Venus-type sources at the NSCL and LBNL respectively. The total measured beam current is close to the maximum current predicted by the multi-species Child Langmuir law in each case, which indicates that beam extraction occurs close to space-charge-limited flow conditions. Prospects for application of the results and further studies on the topic are outlined.

Slides TUZZO05 [0.508 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2020-TUZZO05

About •

Received ※ 28 September 2020 — Revised ※ 28 December 2020 — Accepted ※ 16 January 2021 — Issue date ※ 18 May 2021

Cite •

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

TUZZO06

Beams with Three-Fold Rotational Symmetry: A Theoretical Study

110

C.Y. Wong
ORNL, Oak Ridge, Tennessee, USA
S.M. Lund
FRIB, East Lansing, Michigan, USA

Beams from ECR ion sources have 3-fold transverse rotational symmetry induced by the ECR sextupole. The symmetry imposes equality constraints among transverse beam moments, which can be derived using a theoretical framework we developed. Since the constraints are solely a consequence of the rotational symmetry of external fields, they hold for a multi-species beam with arbitrary composition and space charge intensity. These constraints provide a new tool to analyze phase space properties of ECR beams and their impact on low-energy transport. We prove that, regardless of their triangulated spatial density profile, beams with 3-fold rotational symmetry have the same RMS emittance and Twiss parameters along any transverse direction. These counter-intuitive results are applied to the FRIB Front End to show how symmetry arguments challenge long-standing assumptions and bring clarity to the beam dynamics.

Slides TUZZO06 [0.846 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2020-TUZZO06

About •

Received ※ 28 September 2020 — Revised ※ 14 May 2021 — Accepted ※ 18 May 2021 — Issue date ※ 03 November 2021

Cite •

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