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| MOYZO01 |
Imaging in X-ray Ranges to Locally Investigate the Effect of the Two-Close-Frequency Heating in ECRIS Plasmas |
27 |
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- 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
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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
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Slides MOYZO01 [7.325 MB]
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| DOI • |
reference for this paper
※ https://doi.org/10.18429/JACoW-ECRIS2020-MOYZO01
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| About • |
Received ※ 25 September 2020 — Revised ※ 11 November 2020 — Accepted ※ 17 December 2020 — Issue date ※ 24 January 2021 |
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| MOYZO02 |
High Resolution X-ray Imaging as a Powerful Diagnostics Tool to Investigate ECRIS Plasma Structure and Confinement Dynamics |
32 |
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- 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
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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
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Slides MOYZO02 [26.629 MB]
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| DOI • |
reference for this paper
※ https://doi.org/10.18429/JACoW-ECRIS2020-MOYZO02
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| About • |
Received ※ 27 September 2020 — Revised ※ 02 October 2020 — Accepted ※ 18 November 2020 — Issue date ※ 17 December 2020 |
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| MOYZO03 |
The Relationship Between the Diffusion of Hot Electrons, Plasma Stability, and ECR Ion Source Performance |
38 |
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- B.C. Isherwood
MSU, East Lansing, Michigan, USA
- G. Machicoane
NSCL, East Lansing, Michigan, USA
- G. Machicoane
FRIB, East Lansing, Michigan, USA
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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.
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| DOI • |
reference for this paper
※ https://doi.org/10.18429/JACoW-ECRIS2020-MOYZO03
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| About • |
Received ※ 30 September 2020 — Revised ※ 20 October 2020 — Accepted ※ 19 January 2021 — Issue date ※ 11 April 2022 |
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