ECRIS2020 - List of Authors (Li, J.B.)

Paper

Title

Page

FECR Ion Source Development and Challenges

1

L.T. Sun, Y. Chen, M.Z. Guan, J.W. Guo, J.B. Li, L.B. Li, L.X. Li, W. Lu, E.M. Mei, X.J. Ou, Z. Shen, X.D. Wang, B.M. Wu, W. Wu, C.J. Xin, X.Z. Zhang, H.W. Zhao, S.J. Zheng, L. Zhu
IMP/CAS, Lanzhou, People’s Republic of China
Z. Shen, L.T. Sun
UCAS, Beijing, People’s Republic of China

FECR or the First 4th generation ECR ion source is under development at Institute of Modern Physics (IMP) since 2015. This ion source is aiming to extract intense highly charged heavy ion beams in the order of emA from the dense plasma heated with 45 GHz microwave power. To provide effective magnetic confinement to the 45 GHz ECR plasma, a state of the art Nb₃Sn magnet with min-B configuration is a straightforward technical path. As there is no much precedent references, it has to be designed, prototyped at IMP through in-house development. Meanwhile, other physics and technical challenges to a 4th generation ECR ion source are also tackled at IMP to find feasible solutions. This paper will give a brief review of the critical issues in the development of FECR ion source. A detailed report on the status of FECR prototype magnet development will be presented.

Slides MOWZO01 [16.578 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2020-MOWZO01

About •

Received ※ 27 September 2020 — Revised ※ 02 October 2020 — Accepted ※ 30 November 2020 — Issue date ※ 07 August 2021

Cite •

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

TUWZO02

Tentative Solution to Plasma Chamber Cooling for High Power ECR Ion Source Operation

J.W. Guo, Y.C. Feng, D. Hitz, W. Huang, J.B. Li, L.B. Li, L.X. Li, W. Lu, J.D. Ma, L.T. Sun, Y.Y. Yang, W.H. Zhang, X.Z. Zhang, H.W. Zhao
IMP/CAS, Lanzhou, People’s Republic of China
W. Huang, L.T. Sun
UCAS, Beijing, People’s Republic of China

High charge state electron cyclotron resonance ion source (ECRIS) is characterized by a so-called min-B magnetic field configuration, which provokes the localized plasma over-heating to plasma chamber especially for the 3rd generation ECRISs at high power operation condition. With the increase of rf power, more plasma energy will be dumped to tiny areas and result in a very high localized power density, which is estimated to be up to 1 kW/cm². Few existing ECR plasma chamber cooling designs can withstand such high heat fluxes. In this paper, we report a new plasma chamber cooling design with so-called Micro-channel cooling technology, which can not only realize efficient heat transfer, but also retains a small radial thickness that is beneficial for the radial magnetic field. In order to evaluate the performance of the cooling structure with micro-channel design, experimental cooling loop for high heat flux has been designed and built at IMP. Initial experiments demonstrate that optimized configuration can achieve high heat flux cooling in the range of 1 kW/cm² and beyond. Based on these results, a plasma chamber with micro-channel design for SECRAL has been designed and tested.

Slides TUWZO02 [9.402 MB]

Cite •

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

TUWZO04

Influences of Magnetic Field Parameters to ECRIS Plasma Characteristics

J.B. Li, J.W. Guo, D. Hitz, L.B. Li, L.X. Li, W. Lu, L.T. Sun, X.Z. Zhang, H.W. Zhao, H. Zhao
IMP/CAS, Lanzhou, People’s Republic of China
B.S. Bhaskar, T. Thuillier
LPSC, Grenoble Cedex, France
B.S. Bhaskar, H.A. Koivisto, O.A. Tarvainen, V. Toivanen
JYFL, Jyväskylä, Finland
O.A. Tarvainen
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

To investigate the hot electron population and the appearance of kinetic instabilities in ECRIS plasma, the axially emitted bremsstrahlung spectra and microwave bursts emitted from ECRIS plasma were synchronously measured on SECRAL-II ion source with various magnetic field configurations. The experimental results show that when Bmin/Becr is less than ~0.8, the spectral temperature Ts increases linearly with the Bmin/Becr-ratio when the injection, extraction and radial mirror fields are kept constant. Above this threshold Ts saturates and the electron cyclotron instability appears simultaneously. This study has also demonstrated that Ts decreases linearly with the increase of the average gradient over the ECR surface when the on-axis gradient and hexapole field strengths are constant. In addition, it is found that Ts decreases with the increase of the gradient at the resonance zone at relatively low mirror ratio and is insensitive to the gradient at high mirror ratio when Bmin is constant. Compared to a recent study taken on a fully superconducting ECRIS, this study shows different results discussing the mechanisms behind the correlation of magnetic field parameters to Ts.

Slides TUWZO04 [4.062 MB]

Cite •

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

WEWZO06

Observation of Cyclotron Instabilities in SECRAL-II Ion Source

L.X. Li, Y.C. Feng, J.W. Guo, D. Hitz, J.B. Li, W. Lu, L.T. Sun, W.H. Zhang, X.Z. Zhang, H.W. Zhao
IMP/CAS, Lanzhou, People’s Republic of China

Cyclotron instabilities in Electron Cyclotron Resonance Ion Source (ECRIS) plasmas are related to non-linear interaction between plasma waves and energetic electrons, resulting in strong microwave emission, a burst of energetic electrons escaping the plasma, and the periodic oscillations of the extracted beam currents. Precedent investigation of cyclotron instabilities has proved that Bmin/BECR can be treated as a magnetic field threshold. Recently, experiments with SECRAL-II ion source demonstrate that Bmin/BECR is not the only knob, and other field parameters have also been found to be related to cyclotron instabilities, such as mirror ratio and radial field. Namely, the trigger of cyclotron instability is a combination of many magnetic field parameters. This paper will give the experimental setup at IMP for cyclotron instability investigations and experimental observations will be presented.

Slides WEWZO06 [1.021 MB]

Cite •

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

WEXZO04

Numerical Simulations of Plasma Dynamics in ECRIS Afterglow

L. Lei, X.L. Jin
University of Electronic Science and Technology of China, Chengdu, People’s Republic of China
J.B. Li
IMP/CAS, Lanzhou, People’s Republic of China

Plasma dynamics in the afterglow of ECRIS has been studied through the Particle-in-cell (PIC) simulations. A full 3D implicit electrostatic PIC code was developed to meet the needs of ECRIS simulations and to study the characteristics of the ECR plasma during the afterglow. The initial plasma parameters at the simulation start-up were assumed by referring to the experimental diagnostics of the ECRISs from IMP, Lanzhou. The dynamics of electrons and ions in the presence of the external magnetic field and at the absence of the microwave energy were simulated to study the mechanism of afterglow. Through the abundant diagnostics of the 3D PIC simulation, some ECR plasma features during afterglow including the plasma potential and electron energy distributions could be obtained and analyzed. The goal was to determine the important evolutions that contribute to the afterglow and thus to have a clearer understanding of ECRIS afterglow mode.

Slides WEXZO04 [0.952 MB]

Cite •

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

Paper	Title	Page
MOWZO01	FECR Ion Source Development and Challenges	1
	L.T. Sun, Y. Chen, M.Z. Guan, J.W. Guo, J.B. Li, L.B. Li, L.X. Li, W. Lu, E.M. Mei, X.J. Ou, Z. Shen, X.D. Wang, B.M. Wu, W. Wu, C.J. Xin, X.Z. Zhang, H.W. Zhao, S.J. Zheng, L. Zhu IMP/CAS, Lanzhou, People’s Republic of China Z. Shen, L.T. Sun UCAS, Beijing, People’s Republic of China
	FECR or the First 4th generation ECR ion source is under development at Institute of Modern Physics (IMP) since 2015. This ion source is aiming to extract intense highly charged heavy ion beams in the order of emA from the dense plasma heated with 45 GHz microwave power. To provide effective magnetic confinement to the 45 GHz ECR plasma, a state of the art Nb₃Sn magnet with min-B configuration is a straightforward technical path. As there is no much precedent references, it has to be designed, prototyped at IMP through in-house development. Meanwhile, other physics and technical challenges to a 4th generation ECR ion source are also tackled at IMP to find feasible solutions. This paper will give a brief review of the critical issues in the development of FECR ion source. A detailed report on the status of FECR prototype magnet development will be presented.
	Slides MOWZO01 [16.578 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2020-MOWZO01
About •	Received ※ 27 September 2020 — Revised ※ 02 October 2020 — Accepted ※ 30 November 2020 — Issue date ※ 07 August 2021
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUWZO02	Tentative Solution to Plasma Chamber Cooling for High Power ECR Ion Source Operation
	J.W. Guo, Y.C. Feng, D. Hitz, W. Huang, J.B. Li, L.B. Li, L.X. Li, W. Lu, J.D. Ma, L.T. Sun, Y.Y. Yang, W.H. Zhang, X.Z. Zhang, H.W. Zhao IMP/CAS, Lanzhou, People’s Republic of China W. Huang, L.T. Sun UCAS, Beijing, People’s Republic of China
	High charge state electron cyclotron resonance ion source (ECRIS) is characterized by a so-called min-B magnetic field configuration, which provokes the localized plasma over-heating to plasma chamber especially for the 3rd generation ECRISs at high power operation condition. With the increase of rf power, more plasma energy will be dumped to tiny areas and result in a very high localized power density, which is estimated to be up to 1 kW/cm². Few existing ECR plasma chamber cooling designs can withstand such high heat fluxes. In this paper, we report a new plasma chamber cooling design with so-called Micro-channel cooling technology, which can not only realize efficient heat transfer, but also retains a small radial thickness that is beneficial for the radial magnetic field. In order to evaluate the performance of the cooling structure with micro-channel design, experimental cooling loop for high heat flux has been designed and built at IMP. Initial experiments demonstrate that optimized configuration can achieve high heat flux cooling in the range of 1 kW/cm² and beyond. Based on these results, a plasma chamber with micro-channel design for SECRAL has been designed and tested.
	Slides TUWZO02 [9.402 MB]
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUWZO04	Influences of Magnetic Field Parameters to ECRIS Plasma Characteristics
	J.B. Li, J.W. Guo, D. Hitz, L.B. Li, L.X. Li, W. Lu, L.T. Sun, X.Z. Zhang, H.W. Zhao, H. Zhao IMP/CAS, Lanzhou, People’s Republic of China B.S. Bhaskar, T. Thuillier LPSC, Grenoble Cedex, France B.S. Bhaskar, H.A. Koivisto, O.A. Tarvainen, V. Toivanen JYFL, Jyväskylä, Finland O.A. Tarvainen STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	To investigate the hot electron population and the appearance of kinetic instabilities in ECRIS plasma, the axially emitted bremsstrahlung spectra and microwave bursts emitted from ECRIS plasma were synchronously measured on SECRAL-II ion source with various magnetic field configurations. The experimental results show that when Bmin/Becr is less than ~0.8, the spectral temperature Ts increases linearly with the Bmin/Becr-ratio when the injection, extraction and radial mirror fields are kept constant. Above this threshold Ts saturates and the electron cyclotron instability appears simultaneously. This study has also demonstrated that Ts decreases linearly with the increase of the average gradient over the ECR surface when the on-axis gradient and hexapole field strengths are constant. In addition, it is found that Ts decreases with the increase of the gradient at the resonance zone at relatively low mirror ratio and is insensitive to the gradient at high mirror ratio when Bmin is constant. Compared to a recent study taken on a fully superconducting ECRIS, this study shows different results discussing the mechanisms behind the correlation of magnetic field parameters to Ts.
	Slides TUWZO04 [4.062 MB]
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEWZO06	Observation of Cyclotron Instabilities in SECRAL-II Ion Source
	L.X. Li, Y.C. Feng, J.W. Guo, D. Hitz, J.B. Li, W. Lu, L.T. Sun, W.H. Zhang, X.Z. Zhang, H.W. Zhao IMP/CAS, Lanzhou, People’s Republic of China
	Cyclotron instabilities in Electron Cyclotron Resonance Ion Source (ECRIS) plasmas are related to non-linear interaction between plasma waves and energetic electrons, resulting in strong microwave emission, a burst of energetic electrons escaping the plasma, and the periodic oscillations of the extracted beam currents. Precedent investigation of cyclotron instabilities has proved that Bmin/BECR can be treated as a magnetic field threshold. Recently, experiments with SECRAL-II ion source demonstrate that Bmin/BECR is not the only knob, and other field parameters have also been found to be related to cyclotron instabilities, such as mirror ratio and radial field. Namely, the trigger of cyclotron instability is a combination of many magnetic field parameters. This paper will give the experimental setup at IMP for cyclotron instability investigations and experimental observations will be presented.
	Slides WEWZO06 [1.021 MB]
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEXZO04	Numerical Simulations of Plasma Dynamics in ECRIS Afterglow
	L. Lei, X.L. Jin University of Electronic Science and Technology of China, Chengdu, People’s Republic of China J.B. Li IMP/CAS, Lanzhou, People’s Republic of China
	Plasma dynamics in the afterglow of ECRIS has been studied through the Particle-in-cell (PIC) simulations. A full 3D implicit electrostatic PIC code was developed to meet the needs of ECRIS simulations and to study the characteristics of the ECR plasma during the afterglow. The initial plasma parameters at the simulation start-up were assumed by referring to the experimental diagnostics of the ECRISs from IMP, Lanzhou. The dynamics of electrons and ions in the presence of the external magnetic field and at the absence of the microwave energy were simulated to study the mechanism of afterglow. Through the abundant diagnostics of the 3D PIC simulation, some ECR plasma features during afterglow including the plasma potential and electron energy distributions could be obtained and analyzed. The goal was to determine the important evolutions that contribute to the afterglow and thus to have a clearer understanding of ECRIS afterglow mode.
	Slides WEXZO04 [0.952 MB]
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)