ECRIS2024 - List of Authors (Rodrigues, G.O.)

Paper	Title	Page
TUP13	Transport of intense Bismuth and Uranium beams into a radio frequency quadrupole accelerator	124
	G.O. Rodrigues IUAC, New Delhi, India R.W. Hamm R&M Technical Enterprises, Pleasanton, CA, USA
	A 48.5 MHz RFQ has been designed to transport and accelerate ²³⁸U⁴⁰⁺ (0.52 emA) and ²⁰⁹Bi³⁰⁺ (1.047 emA) beams extracted from a high performance ECR ion source. The RFQ design comprises of a pre-buncher built into the vanes to narrow the transmitted charge state distribution as much as possible. The design parameters as a function of cell length is optimised on ²⁰⁹Bi³⁰⁺. It is shown that the losses of various ions without using an inlet aperture are inevitable, but by proper coating of the vanes of the RFQ, sputtering can be minimised to a great extent. Titanium shows better results when compared with gold or copper and this has been verified using the modelling results from SRIM. The design details of matching the ECR and the RFQ and the predicted performance will be presented.
DOI •	reference for this paper ※ doi:10.18429/JACoW-ECRIS2024-TUP13
About •	Received ※ 12 March 2025 — Revised ※ 01 May 2025 — Accepted ※ 29 June 2025 — Issued ※ 29 June 2025
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEA3	A plasma based, charge state stripper for heavy ion accelerators	144
	G.O. Rodrigues IUAC, New Delhi, India
	The ionization of ions to a higher charge state is of central importance for the development of new Accelerator Facilities like FAIR [1], and the resulting cost savings. Currently, mainly gas and foil strippers are used for increasing the charge state even after using a high performance ECR ion source in a typical Accelerator chain. Even when the foil or/and gas stripper efficiency or lifetime has proved to be less than optimal, as these alternatives either require great effort or are practically not suitable for smooth operation in the long term. Free electrons in highly ionized plasmas [2,3] can be effectively used for improving the charge state of heavy ions as the rates of radiative recombination of free electrons are much smaller than those of electron capture on bound electrons, which leads to a substantial increase of the effective charge in a plasma compared to a cold-gas target of the same element. Theta and Z pinch plasmas are possible options which have been explored and experimentally studied at IAP, Frankfurt, Germany [4]. Typical electron line densities required to be achieved are in the range of 10¹⁶ to 10¹⁹ cm⁻³ and electron temperatures of the order of few tens of eV are found to be very favourable as per modelling with the FLYCHK code [5], but also extremely challenging. Such a plasma device, the challenges to be overcome, together with their design details will be presented. [1] https://fair-center.eu/ [2] E. Nardi and Z. Zinamon, Phys. Rev. Lett., vol. 49, p. 1251, 1982. [3] T. Peter and J. Meyer-ter-Vehn, “Energy loss of heavy ions in dense plasma. II. Nonequilibrium charge states and stopping powers”, Phys. Rev. A, vol. 43, pp. 2015–2030, 1991. doi:10.1103/PhysRevA.43.2015 [4] C. Teske, J. Jacoby, F. Senzel, W. Schweizer, Phys. Plasmas, vol. 17, p. 043501, 2010. [5] FLYCHK code: www-amdis.iaea.org
	Slides WEA3 [5.462 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-ECRIS2024-WEA3
About •	Received ※ 28 March 2025 — Revised ※ 26 May 2025 — Accepted ※ 29 June 2025 — Issued ※ 30 June 2025
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Transport of intense Bismuth and Uranium beams into a radio frequency quadrupole accelerator

124

G.O. Rodrigues
IUAC, New Delhi, India
R.W. Hamm
R&M Technical Enterprises, Pleasanton, CA, USA

A 48.5 MHz RFQ has been designed to transport and accelerate ²³⁸U⁴⁰⁺ (0.52 emA) and ²⁰⁹Bi³⁰⁺ (1.047 emA) beams extracted from a high performance ECR ion source. The RFQ design comprises of a pre-buncher built into the vanes to narrow the transmitted charge state distribution as much as possible. The design parameters as a function of cell length is optimised on ²⁰⁹Bi³⁰⁺. It is shown that the losses of various ions without using an inlet aperture are inevitable, but by proper coating of the vanes of the RFQ, sputtering can be minimised to a great extent. Titanium shows better results when compared with gold or copper and this has been verified using the modelling results from SRIM. The design details of matching the ECR and the RFQ and the predicted performance will be presented.

DOI •

reference for this paper ※ doi:10.18429/JACoW-ECRIS2024-TUP13

About •

Received ※ 12 March 2025 — Revised ※ 01 May 2025 — Accepted ※ 29 June 2025 — Issued ※ 29 June 2025

Cite •

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

WEA3

A plasma based, charge state stripper for heavy ion accelerators

144

G.O. Rodrigues
IUAC, New Delhi, India

The ionization of ions to a higher charge state is of central importance for the development of new Accelerator Facilities like FAIR [1], and the resulting cost savings. Currently, mainly gas and foil strippers are used for increasing the charge state even after using a high performance ECR ion source in a typical Accelerator chain. Even when the foil or/and gas stripper efficiency or lifetime has proved to be less than optimal, as these alternatives either require great effort or are practically not suitable for smooth operation in the long term. Free electrons in highly ionized plasmas [2,3] can be effectively used for improving the charge state of heavy ions as the rates of radiative recombination of free electrons are much smaller than those of electron capture on bound electrons, which leads to a substantial increase of the effective charge in a plasma compared to a cold-gas target of the same element. Theta and Z pinch plasmas are possible options which have been explored and experimentally studied at IAP, Frankfurt, Germany [4]. Typical electron line densities required to be achieved are in the range of 10¹⁶ to 10¹⁹ cm⁻³ and electron temperatures of the order of few tens of eV are found to be very favourable as per modelling with the FLYCHK code [5], but also extremely challenging. Such a plasma device, the challenges to be overcome, together with their design details will be presented.
[1] https://fair-center.eu/
[2] E. Nardi and Z. Zinamon, Phys. Rev. Lett., vol. 49, p. 1251, 1982.
[3] T. Peter and J. Meyer-ter-Vehn, “Energy loss of heavy ions in dense plasma. II. Nonequilibrium charge states and stopping powers”, Phys. Rev. A, vol. 43, pp. 2015–2030, 1991. doi:10.1103/PhysRevA.43.2015
[4] C. Teske, J. Jacoby, F. Senzel, W. Schweizer, Phys. Plasmas, vol. 17, p. 043501, 2010.
[5] FLYCHK code: www-amdis.iaea.org

Slides WEA3 [5.462 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-ECRIS2024-WEA3

About •

Received ※ 28 March 2025 — Revised ※ 26 May 2025 — Accepted ※ 29 June 2025 — Issued ※ 30 June 2025

Cite •

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