ECRIS2020 - Classification: 01: Fundamental Processes

Paper	Title	Page
MOYZO01	Imaging in X-ray Ranges to Locally Investigate the Effect of the Two-Close-Frequency Heating in ECRIS Plasmas	27
	R. Rácz, S. Biri, Z. Perduk Atomki, Debrecen, Hungary G. Castro, L. Celona, S. Gammino, D. Mascali, M. Mazzaglia, E. Naselli, G. Torrisi INFN/LNS, Catania, Italy A. Galatà INFN/LNL, Legnaro (PD), Italy E. Naselli Catania University, Catania, Italy J. Pálinkás University Debrecen, Debrecen, Hungary
	Plasma instabilities limit the ECR Ion Sources performances in terms of flux of the extracted highly charged ions by causing beam ripple and unstable operation conditions. In a 14 GHz ECRIS (Atomki, Debrecen), the effect on the plasma instabilities in an Argon plasma at Two Close Frequencies heating scheme (the frequency gap is smaller than 1 GHz) has been explored. A special multi-diagnostic setup [1, 2] has been designed and implemented consisting of detectors for the simultaneous collection of plasma radio-self-emission and of high spatial resolution X-ray images in the 500 eV - 20 keV energy domain (using an X-ray pin-hole camera setup). We present the comparison of plasma structural changes as observed from X-ray images in single and double-frequency operations. The latter has been particularly correlated to the confinement and velocity anisotropy, also by considering results coming from numerical simulations. [1] S. Biri et al. Journal of Instrumentation 13(11):C11016 DOI: 10.1088/1748-0221/13/11/C11016 [2] E. Naselli et. al. Journal of Instrumentation 14(10):C10008 DOI: 10.1088/1748-0221/14/10/C10008
	Slides MOYZO01 [7.325 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2020-MOYZO01
About •	Received ※ 25 September 2020 — Revised ※ 11 November 2020 — Accepted ※ 17 December 2020 — Issue date ※ 24 January 2021
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOYZO02	High Resolution X-ray Imaging as a Powerful Diagnostics Tool to Investigate ECRIS Plasma Structure and Confinement Dynamics	32
	E. Naselli, G. Castro, L. Celona, S. Gammino, D. Mascali, M. Mazzaglia, G. Torrisi INFN/LNS, Catania, Italy S. Biri, Z. Perduk, R. Rácz Atomki, Debrecen, Hungary A. Galatà INFN/LNL, Legnaro (PD), Italy E. Naselli Catania University, Catania, Italy J. Pálinkás DU, Debrecen, Hungary
	High resolution spatially-resolved X-ray spectroscopy, by means of a X-ray pin-hole camera setup* ** operating in the 0.5-20 keV energy domain, is a very powerful method for ECRIS plasma structure evaluation. We present the setup installed at a 14 GHz ECRIS (ATOMKI, Debrecen), including a multi-layered collimator enabling measurements up to several hundreds of watts of RF pumping power and the achieved spatial and energy resolution (0.5 mm and 300 eV). Results coming by a new algorithm for analyzing Integrated (multi-events detection) and Photon-Counted images (single-event detection) to perform energy-resolved investigation will be described. The analysis permits to investigate High-Dynamic-Range (HDR) and spectrally resolved images, to study the effect of the axial and radial confinement (even separately), the plasma radius, the fluxes of deconfined electrons distinguishing fluorescence lines of the materials of the plasma chamber (Ti, Ta) from plasma (Ar) fluorescence lines. This method allows a detailed characterization of warm electrons, important for ionization, and to quantitatively estimate local plasma density and spectral temperature pixel-by-pixel. S. Biri et al., JINST 13(11):C11016-C11016, DOI:10.1088/1748-0221/13/11/C11016 *E. Naselli et al., JINST 14(10):C10008-C10008, DOI:10.1088/1748-0221/14/10/C10008
	Slides MOYZO02 [26.629 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2020-MOYZO02
About •	Received ※ 27 September 2020 — Revised ※ 02 October 2020 — Accepted ※ 18 November 2020 — Issue date ※ 17 December 2020
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOYZO03	The Relationship Between the Diffusion of Hot Electrons, Plasma Stability, and ECR Ion Source Performance	38
	B.C. Isherwood MSU, East Lansing, Michigan, USA G. Machicoane NSCL, East Lansing, Michigan, USA G. Machicoane FRIB, East Lansing, Michigan, USA
	Funding: This research was made possible by the National Science Foundation under NSF Grant 1632761 and the U.S. Department of Energy Award Number DE-SC0018362. Plasma instabilities complicate the operation of electron cyclotron resonance ion sources. In particular, quasi-periodic losses of electrons from confinement due to kinetic cyclotron instabilities hinder ion source performance. Empirical scaling laws help guide the development of sources away from the most unstable operating points but are poorly understood. Further advancement of ECR ion source technologies requires a deeper understanding of instabilities, scaling laws, and internal processes of the ion source plasma itself. We present here results of an experimental study into these instabilities and scaling laws, and measurements of hot electron diffusion (E > 10 keV) from the 18 GHz SUSI ECRIS at the NSCL. Measurements of the average argon current and the standard deviation of their variations across multiple unstable operating points are shown. These measurements are compared to measurements of electrons that diffuse axially from the plasma chamber. In doing so it will be shown how controlling the diffusion of electrons control the stability of the plasma and optimize the ion source’s performance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2020-MOYZO03
About •	Received ※ 30 September 2020 — Revised ※ 20 October 2020 — Accepted ※ 19 January 2021 — Issue date ※ 11 April 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUWZO01	Measurements of Plasma Parameters Near Resonance Zones and Peripheral Regions in ECRIS	60
	W. Kubo, S. Harisaki, Y. Kato, I. Owada, K. Sato, K. Tsuda Osaka University, Graduate School of Engineering, Osaka, Japan
	We have investigated how to produce multicharged ions efficiently. Recently, we have focused on waves propagations in plasma and conducted the Upper-hybrid Resonance (UHR) experiments. [1] We have also conducted experiments heating by the coaxial semi-dipole antenna to enhance the right-hand polarization wave, which contributes to ECR. [2] Multicharged ion beams have been improved using various means, e.g., the increase of the magnetic field and the microwave frequency, the DC biased plate-tuner, mixing low z gases, and the multiplex frequencies heating. However, the microwave launching position has been empirically determined on conventional ECRIS’s. There is still some room for improvement with the respect to more efficient excitation of the wave propagation. In this research, we estimate the wave propagation near the ECR zone, and in the opposite peripheral region beyond it. We measure plasma parameters in those regions by two Langmuir probes inserted into each location at the same time. In near future, we optimize the microwave-launching in the case of the fundamental frequency for ECR and the second frequency for UHR in order to enhance their incidence to the vacuum chamber. [1]Y. Kato et al, AIP Conf. Proc. 2011, 020005 (2018). [2]W. Kubo, et al, RSI, 2020, 91, 023317 (2020).
	Slides TUWZO01 [5.656 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2020-TUWZO01
About •	Received ※ 24 September 2020 — Revised ※ 01 October 2020 — Accepted ※ 03 December 2020 — Issue date ※ 16 February 2022
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)

TUXZO01	A Proposed Explanation of High-Minimum-B Instabilities	68
	D.S. Todd, J.Y. Benitez LBNL, Berkeley, California, USA
	It is well-known that electron cyclotron resonance ion sources exhibit instabilities when these sources’ minimum magnetic fields are approximately 80% of the resonant field or greater, but the reasons for this instability have yet to be satisfactorily explained. We show that raising the minimum field makes much faster heating modes accessible at lower energies that invite the onset of kinetic instabilities.
	Slides TUXZO01 [3.566 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2020-TUXZO01
About •	Received ※ 28 September 2020 — Revised ※ 06 October 2020 — Accepted ※ 03 December 2020 — Issue date ※ 13 December 2020
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUXZO02	Experimental Evidence of E.M. trapped E.M. waves in a Simple Mirror Magnetic-Trap
	G. Castro, L. Celona, S. Gammino, O. Leonardi, D. Mascali, G. Torrisi INFN/LNS, Catania, Italy R. Miracoli ESS Bilbao, Zamudio, Spain
	This work presents the first experimental characterization of cavity modes trapped within a plasma column in an axis-symmetric magnetic trap. Trapped wave has been characterized by means of a movable antenna as a function of the B_min/B_ECR ratio and plasma parameters. The study demonstrates that E.M waves can be enclosed two R-cutoff layers, close to the B minimum position. Results suggest that the trapped waves consist of waves propagating across the magnetic field and storing large part of the E.M. power. If R-cut-off is removed by increasing the density, trapped waves are not detected longer. A typical Electron Energy Distribution Function composed by two different electron populations is measured in the layer where trapped waves are revealed, suggesting that additional heating is occurring.
	Slides TUXZO02 [6.058 MB]
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUXZO03	Angular Distribution Measurement of Atoms Evaporated from a Resistive Oven Applied to Ion Beam Production	72
	T. Thuillier, A. Leduc LPSC, Grenoble Cedex, France O. Bajeat, A. Leduc, L. Maunoury GANIL, Caen, France
	A low temperature oven has been developed to produce calcium beam with Electron Cyclotron Resonance Ion Source. The atom flux from the oven has been studied experimentally as a function of the temperature and the angle of emission by means of a quartz microbalance. The absolute flux measurement permitted to derive Antoine’s coefficient for the calcium sample used : A=8.98± 0.07 and B=7787± 110 in standard unit. The angular FWHM of the atom flux distribution is found to be 53.7±7.3 °at 848K. The atom flux hysteresis observed experimentally in several laboratories is explained as follows: at first calcium heating, the evaporation comes from the sample only resulting in a small evaporation rate. once a full calcium layer has formed on the crucible refractory wall, the caclcium evaporation surface includes the crucible’s enhancing dramatically the evaporation rate for a givent temperature. A Monte-Carlo code, developed to reproduce and investigate the oven behaviour as a function of temperature is presented. A discussion on the gas regime in the oven is proposed as a function of its temperature. A fair agreement between experiment and simulation is found.
	Slides TUXZO03 [4.542 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2020-TUXZO03
About •	Received ※ 28 September 2020 — Revised ※ 19 February 2021 — Accepted ※ 21 July 2021 — Issue date ※ 16 April 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUZZO03	Study on the Correlation between Energy Distribution of Electrons Lost from the Confinement and Plasma Bremsstrahlung on a min-B ECR Plasmas
	B.S. Bhaskar, T. Thuillier LPSC, Grenoble Cedex, France B.S. Bhaskar, T. Kalvas, H.A. Koivisto, R.J. Kronholm, M.S.P. Marttinen, O.A. Tarvainen, V. Toivanen JYFL, Jyväskylä, Finland I. Izotov, V. Skalyga IAP/RAS, Nizhny Novgorod, Russia O.A. Tarvainen STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	Funding: The work has received funding from the Academy of Finland under the Academy of Finland Project funding (No. 315855) and from University Grenoble Alps under EMERGENCE-project. The study of plasma bremsstrahlung has been used as a diagnostic tool for understanding the behavior of confined plasma in Electron Cyclotron Resonance Ion Sources (ECRIS). In order to understand the relation connecting the confined plasma and the electrons escaping the confinement, a series of measurements have been made to measure the bremsstrahlung produced in the axial and radial direction along with the Lost Electron Energy Distribution (LEED) axially on JYFL 14 GHz ECR. We present here the effect of various source parameters on the axial and radial bremsstrahlung along with the LEED on a min-B confined ECR plasma. The measured LEED has been found to show a correlation with bremsstrahlung measurement and also have observed as a potential diagnostic method for instability. The explanation for observed LEED and bremsstrahlung trends is provided.
	Slides TUZZO03 [1.520 MB]
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEWZO04	Producing Multicharged Ions by Pulse Modulated Microwaves at Mixing Low Z Gases on ECRIS	122
	S. Harisaki, Y. Kato, W. Kubo, I. Owada, K. Sato, K. Tsuda Osaka University, Graduate School of Engineering, Osaka, Japan
	We are aiming at producing various ion beams in ECRIS. In the case of producing multicharged ion beams, we try to enhance loss channel of low Z ions by means of adding pulse modulated microwaves to conventional gas mixing method.* Through these experiments, we explore the feasibility of selectively heating specific ions with pulse modulated microwaves and launching another low frequency RF waves. In gas mixing experiment, we use Helium as low Z gas for production of multicharged Ar and Xenon ion beams. These experiments are conducted by keeping the total pressure constant and changing the mixing ratio of Helium. The time scale of pulsed microwave is typically several to several hundreds of microseconds. We optimize the pulse period and duty ratio for producing multicharged ion beams. These effects are investigated to measure Charge State Distributions (CSDs). Also, we can measure the emittance using wire probe and multi slit attached to Ion Beam Irradiation System (IBIS). ** We estimate the normalized emittance from this measurement to determine index of ion temperature in the ECRIS. In this paper, we mainly describe the results of these active and additive methods at the ECRIS. M. Muramatsu, et al., Review of Scientific Instruments, 87, 02C110(2016). *K. Okumura, et al., Review of Scientific Instruments, 91, 023311(2020).
	Slides WEWZO04 [1.283 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2020-WEWZO04
About •	Received ※ 24 September 2020 — Revised ※ 27 September 2020 — Accepted ※ 03 December 2020 — Issue date ※ 15 July 2021
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)

Paper

Title

Page

Imaging in X-ray Ranges to Locally Investigate the Effect of the Two-Close-Frequency Heating in ECRIS Plasmas

27

R. Rácz, S. Biri, Z. Perduk
Atomki, Debrecen, Hungary
G. Castro, L. Celona, S. Gammino, D. Mascali, M. Mazzaglia, E. Naselli, G. Torrisi
INFN/LNS, Catania, Italy
A. Galatà
INFN/LNL, Legnaro (PD), Italy
E. Naselli
Catania University, Catania, Italy
J. Pálinkás
University Debrecen, Debrecen, Hungary

Plasma instabilities limit the ECR Ion Sources performances in terms of flux of the extracted highly charged ions by causing beam ripple and unstable operation conditions. In a 14 GHz ECRIS (Atomki, Debrecen), the effect on the plasma instabilities in an Argon plasma at Two Close Frequencies heating scheme (the frequency gap is smaller than 1 GHz) has been explored. A special multi-diagnostic setup [1, 2] has been designed and implemented consisting of detectors for the simultaneous collection of plasma radio-self-emission and of high spatial resolution X-ray images in the 500 eV - 20 keV energy domain (using an X-ray pin-hole camera setup). We present the comparison of plasma structural changes as observed from X-ray images in single and double-frequency operations. The latter has been particularly correlated to the confinement and velocity anisotropy, also by considering results coming from numerical simulations.
[1] S. Biri et al. Journal of Instrumentation 13(11):C11016 DOI: 10.1088/1748-0221/13/11/C11016
[2] E. Naselli et. al. Journal of Instrumentation 14(10):C10008 DOI: 10.1088/1748-0221/14/10/C10008

Slides MOYZO01 [7.325 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2020-MOYZO01

About •

Received ※ 25 September 2020 — Revised ※ 11 November 2020 — Accepted ※ 17 December 2020 — Issue date ※ 24 January 2021

Cite •

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

MOYZO02

High Resolution X-ray Imaging as a Powerful Diagnostics Tool to Investigate ECRIS Plasma Structure and Confinement Dynamics

32

E. Naselli, G. Castro, L. Celona, S. Gammino, D. Mascali, M. Mazzaglia, G. Torrisi
INFN/LNS, Catania, Italy
S. Biri, Z. Perduk, R. Rácz
Atomki, Debrecen, Hungary
A. Galatà
INFN/LNL, Legnaro (PD), Italy
E. Naselli
Catania University, Catania, Italy
J. Pálinkás
DU, Debrecen, Hungary

High resolution spatially-resolved X-ray spectroscopy, by means of a X-ray pin-hole camera setup* ** operating in the 0.5-20 keV energy domain, is a very powerful method for ECRIS plasma structure evaluation. We present the setup installed at a 14 GHz ECRIS (ATOMKI, Debrecen), including a multi-layered collimator enabling measurements up to several hundreds of watts of RF pumping power and the achieved spatial and energy resolution (0.5 mm and 300 eV). Results coming by a new algorithm for analyzing Integrated (multi-events detection) and Photon-Counted images (single-event detection) to perform energy-resolved investigation will be described. The analysis permits to investigate High-Dynamic-Range (HDR) and spectrally resolved images, to study the effect of the axial and radial confinement (even separately), the plasma radius, the fluxes of deconfined electrons distinguishing fluorescence lines of the materials of the plasma chamber (Ti, Ta) from plasma (Ar) fluorescence lines. This method allows a detailed characterization of warm electrons, important for ionization, and to quantitatively estimate local plasma density and spectral temperature pixel-by-pixel.
*S. Biri et al., JINST 13(11):C11016-C11016, DOI:10.1088/1748-0221/13/11/C11016
**E. Naselli et al., JINST 14(10):C10008-C10008, DOI:10.1088/1748-0221/14/10/C10008

Slides MOYZO02 [26.629 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2020-MOYZO02

About •

Received ※ 27 September 2020 — Revised ※ 02 October 2020 — Accepted ※ 18 November 2020 — Issue date ※ 17 December 2020

Cite •

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

MOYZO03

The Relationship Between the Diffusion of Hot Electrons, Plasma Stability, and ECR Ion Source Performance

38

B.C. Isherwood
MSU, East Lansing, Michigan, USA
G. Machicoane
NSCL, East Lansing, Michigan, USA
G. Machicoane
FRIB, East Lansing, Michigan, USA

Funding: This research was made possible by the National Science Foundation under NSF Grant 1632761 and the U.S. Department of Energy Award Number DE-SC0018362.
Plasma instabilities complicate the operation of electron cyclotron resonance ion sources. In particular, quasi-periodic losses of electrons from confinement due to kinetic cyclotron instabilities hinder ion source performance. Empirical scaling laws help guide the development of sources away from the most unstable operating points but are poorly understood. Further advancement of ECR ion source technologies requires a deeper understanding of instabilities, scaling laws, and internal processes of the ion source plasma itself. We present here results of an experimental study into these instabilities and scaling laws, and measurements of hot electron diffusion (E > 10 keV) from the 18 GHz SUSI ECRIS at the NSCL. Measurements of the average argon current and the standard deviation of their variations across multiple unstable operating points are shown. These measurements are compared to measurements of electrons that diffuse axially from the plasma chamber. In doing so it will be shown how controlling the diffusion of electrons control the stability of the plasma and optimize the ion source’s performance.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2020-MOYZO03

About •

Received ※ 30 September 2020 — Revised ※ 20 October 2020 — Accepted ※ 19 January 2021 — Issue date ※ 11 April 2022

Cite •

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

TUWZO01

Measurements of Plasma Parameters Near Resonance Zones and Peripheral Regions in ECRIS

60

W. Kubo, S. Harisaki, Y. Kato, I. Owada, K. Sato, K. Tsuda
Osaka University, Graduate School of Engineering, Osaka, Japan

We have investigated how to produce multicharged ions efficiently. Recently, we have focused on waves propagations in plasma and conducted the Upper-hybrid Resonance (UHR) experiments. [1] We have also conducted experiments heating by the coaxial semi-dipole antenna to enhance the right-hand polarization wave, which contributes to ECR. [2] Multicharged ion beams have been improved using various means, e.g., the increase of the magnetic field and the microwave frequency, the DC biased plate-tuner, mixing low z gases, and the multiplex frequencies heating. However, the microwave launching position has been empirically determined on conventional ECRIS’s. There is still some room for improvement with the respect to more efficient excitation of the wave propagation. In this research, we estimate the wave propagation near the ECR zone, and in the opposite peripheral region beyond it. We measure plasma parameters in those regions by two Langmuir probes inserted into each location at the same time. In near future, we optimize the microwave-launching in the case of the fundamental frequency for ECR and the second frequency for UHR in order to enhance their incidence to the vacuum chamber.
[1]Y. Kato et al, AIP Conf. Proc. 2011, 020005 (2018).
[2]W. Kubo, et al, RSI, 2020, 91, 023317 (2020).

Slides TUWZO01 [5.656 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2020-TUWZO01

About •

Received ※ 24 September 2020 — Revised ※ 01 October 2020 — Accepted ※ 03 December 2020 — Issue date ※ 16 February 2022

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)

TUXZO01

A Proposed Explanation of High-Minimum-B Instabilities

68

D.S. Todd, J.Y. Benitez
LBNL, Berkeley, California, USA

It is well-known that electron cyclotron resonance ion sources exhibit instabilities when these sources’ minimum magnetic fields are approximately 80% of the resonant field or greater, but the reasons for this instability have yet to be satisfactorily explained. We show that raising the minimum field makes much faster heating modes accessible at lower energies that invite the onset of kinetic instabilities.

Slides TUXZO01 [3.566 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2020-TUXZO01

About •

Received ※ 28 September 2020 — Revised ※ 06 October 2020 — Accepted ※ 03 December 2020 — Issue date ※ 13 December 2020

Cite •

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

TUXZO02

Experimental Evidence of E.M. trapped E.M. waves in a Simple Mirror Magnetic-Trap

G. Castro, L. Celona, S. Gammino, O. Leonardi, D. Mascali, G. Torrisi
INFN/LNS, Catania, Italy
R. Miracoli
ESS Bilbao, Zamudio, Spain

This work presents the first experimental characterization of cavity modes trapped within a plasma column in an axis-symmetric magnetic trap. Trapped wave has been characterized by means of a movable antenna as a function of the B_min/B_ECR ratio and plasma parameters. The study demonstrates that E.M waves can be enclosed two R-cutoff layers, close to the B minimum position. Results suggest that the trapped waves consist of waves propagating across the magnetic field and storing large part of the E.M. power. If R-cut-off is removed by increasing the density, trapped waves are not detected longer. A typical Electron Energy Distribution Function composed by two different electron populations is measured in the layer where trapped waves are revealed, suggesting that additional heating is occurring.

Slides TUXZO02 [6.058 MB]

Cite •

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

TUXZO03

Angular Distribution Measurement of Atoms Evaporated from a Resistive Oven Applied to Ion Beam Production

72

T. Thuillier, A. Leduc
LPSC, Grenoble Cedex, France
O. Bajeat, A. Leduc, L. Maunoury
GANIL, Caen, France

A low temperature oven has been developed to produce calcium beam with Electron Cyclotron Resonance Ion Source. The atom flux from the oven has been studied experimentally as a function of the temperature and the angle of emission by means of a quartz microbalance. The absolute flux measurement permitted to derive Antoine’s coefficient for the calcium sample used : A=8.98± 0.07 and B=7787± 110 in standard unit. The angular FWHM of the atom flux distribution is found to be 53.7±7.3 °at 848K. The atom flux hysteresis observed experimentally in several laboratories is explained as follows: at first calcium heating, the evaporation comes from the sample only resulting in a small evaporation rate. once a full calcium layer has formed on the crucible refractory wall, the caclcium evaporation surface includes the crucible’s enhancing dramatically the evaporation rate for a givent temperature. A Monte-Carlo code, developed to reproduce and investigate the oven behaviour as a function of temperature is presented. A discussion on the gas regime in the oven is proposed as a function of its temperature. A fair agreement between experiment and simulation is found.

Slides TUXZO03 [4.542 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2020-TUXZO03

About •

Received ※ 28 September 2020 — Revised ※ 19 February 2021 — Accepted ※ 21 July 2021 — Issue date ※ 16 April 2022

Cite •

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

TUZZO03

Study on the Correlation between Energy Distribution of Electrons Lost from the Confinement and Plasma Bremsstrahlung on a min-B ECR Plasmas

B.S. Bhaskar, T. Thuillier
LPSC, Grenoble Cedex, France
B.S. Bhaskar, T. Kalvas, H.A. Koivisto, R.J. Kronholm, M.S.P. Marttinen, O.A. Tarvainen, V. Toivanen
JYFL, Jyväskylä, Finland
I. Izotov, V. Skalyga
IAP/RAS, Nizhny Novgorod, Russia
O.A. Tarvainen
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

Funding: The work has received funding from the Academy of Finland under the Academy of Finland Project funding (No. 315855) and from University Grenoble Alps under EMERGENCE-project.
The study of plasma bremsstrahlung has been used as a diagnostic tool for understanding the behavior of confined plasma in Electron Cyclotron Resonance Ion Sources (ECRIS). In order to understand the relation connecting the confined plasma and the electrons escaping the confinement, a series of measurements have been made to measure the bremsstrahlung produced in the axial and radial direction along with the Lost Electron Energy Distribution (LEED) axially on JYFL 14 GHz ECR. We present here the effect of various source parameters on the axial and radial bremsstrahlung along with the LEED on a min-B confined ECR plasma. The measured LEED has been found to show a correlation with bremsstrahlung measurement and also have observed as a potential diagnostic method for instability. The explanation for observed LEED and bremsstrahlung trends is provided.

Slides TUZZO03 [1.520 MB]

Cite •

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

WEWZO04

Producing Multicharged Ions by Pulse Modulated Microwaves at Mixing Low Z Gases on ECRIS

122

S. Harisaki, Y. Kato, W. Kubo, I. Owada, K. Sato, K. Tsuda
Osaka University, Graduate School of Engineering, Osaka, Japan

We are aiming at producing various ion beams in ECRIS. In the case of producing multicharged ion beams, we try to enhance loss channel of low Z ions by means of adding pulse modulated microwaves to conventional gas mixing method.* Through these experiments, we explore the feasibility of selectively heating specific ions with pulse modulated microwaves and launching another low frequency RF waves. In gas mixing experiment, we use Helium as low Z gas for production of multicharged Ar and Xenon ion beams. These experiments are conducted by keeping the total pressure constant and changing the mixing ratio of Helium. The time scale of pulsed microwave is typically several to several hundreds of microseconds. We optimize the pulse period and duty ratio for producing multicharged ion beams. These effects are investigated to measure Charge State Distributions (CSDs). Also, we can measure the emittance using wire probe and multi slit attached to Ion Beam Irradiation System (IBIS). ** We estimate the normalized emittance from this measurement to determine index of ion temperature in the ECRIS. In this paper, we mainly describe the results of these active and additive methods at the ECRIS.
*M. Muramatsu, et al., Review of Scientific Instruments, 87, 02C110(2016).
**K. Okumura, et al., Review of Scientific Instruments, 91, 023311(2020).

Slides WEWZO04 [1.283 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2020-WEWZO04

About •

Received ※ 24 September 2020 — Revised ※ 27 September 2020 — Accepted ※ 03 December 2020 — Issue date ※ 15 July 2021

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)