Preface for the special topic on “ion source diagnostics”

Fantz, U.; Tarvainen, O.

doi:10.1063/5.0114511

Cited by 3 publications

(2 citation statements)

References 15 publications

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“…Among other techniques, X-ray plasma diagnostics were developed over the years, allowing for the volumetric characterization of ECR plasmas. The volume-integrated X-ray diagnostics in the soft-X domain (from 1 keV to 30 keV) were adopted to estimate the spectral temperatures in different plasma conditions and various ECR setups vs RF power, gas pressure, and the magnetic field profile [16,[31][32][33][34][35][36][37][38][39].…”

Section: X-ray Pin-hole Cameramentioning

confidence: 99%

The Multi-Detectors System of the PANDORA Facility: Focus on the Full-Field Pin-Hole CCD System for X-ray Imaging and Spectroscopy

Mascali,

Naselli,

Biri

et al. 2024

Condensed Matter

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PANDORA (Plasmas for Astrophysics Nuclear Decays Observation and Radiation for Archaeometry) is an INFN project aiming at measuring, for the first time, possible variations in in-plasma β-decay lifetimes in isotopes of astrophysical interest as a function of thermodynamical conditions of the in-laboratory controlled plasma environment. Theoretical predictions indicate that the ionization state can dramatically modify the β-decay lifetime (even of several orders of magnitude). The PANDORA experimental approach consists of confining a plasma able to mimic specific stellar-like conditions and measuring the nuclear decay lifetime as a function of plasma parameters. The β-decay events will be measured by detecting the γ-ray emitted by the daughter nuclei, using an array of 12 HPGe detectors placed around the magnetic trap. In this frame, plasma parameters have to be continuously monitored online. For this purpose, an innovative, non-invasive multi-diagnostic system, including high-resolution time- and space-resolved X-ray analysis, was developed, which will work synergically with the γ-rays detection system. In this contribution, we will describe this multi-diagnostics system with a focus on spatially resolved high-resolution X-ray spectroscopy. The latter is performed by a pin-hole X-ray camera setup operating in the 0.5–20 keV energy domain. The achieved spatial and energy resolutions are 450 µm and 230 eV at 8.1 keV, respectively. An analysis algorithm was specifically developed to obtain SPhC (Single Photon-Counted) images and local plasma emission spectrum in High-Dynamic-Range (HDR) mode. Thus, investigations of image regions where the emissivity can change by even orders of magnitude are now possible. Post-processing analysis is also able to remove readout noise, which is often observable and dominant at very low exposure times (ms). Several measurements have already been used in compact magnetic plasma traps, e.g., the ATOMKI ECRIS in Debrecen and the Flexible Plasma Trap at LNS. The main outcomes will be shortly presented. The collected data allowed for a quantitative and absolute evaluation of local emissivity, the elemental analysis, and the local evaluation of plasma density and temperature. This paper also discusses the new plasma emission models, implemented on PIC-ParticleInCell codes, which were developed to obtain powerful 3D maps of the X-rays emitted by the magnetically confined plasma. These data also support the evaluation procedure of spatially resolved plasma parameters from the experimental spectra as well as, in the near future, the development of appropriate algorithms for the tomographic reconstruction of plasma parameters in the X-ray domain. The described setups also include the most recent upgrade, consisting of the use of fast X-ray shutters with special triggering systems that will be routinely implemented to perform both space- and time-resolved spectroscopy during transient, stable, and turbulent plasma regimes (in the ms timescale).

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Section: X-ray Pin-hole Cameramentioning

confidence: 99%

The Multi-Detectors System of the PANDORA Facility: Focus on the Full-Field Pin-Hole CCD System for X-ray Imaging and Spectroscopy

Mascali,

Naselli,

Biri

et al. 2024

Condensed Matter

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“…Therefore, to acquire a deeper understanding of the plasma properties, non-invasive diagnostic methods are needed for reliable analysis of the plasma. There are multiple different ways of studying plasma without influencing it [1,2], for example using the escaping ion and electron populations or through the different types of radiation emissions, such as bremsstrahlung and microwaves [3]. Plasma also emits radiation in the visible part of the light spectrum, which enables the use of optical emission spectroscopy (OES) as a non-invasive diagnostic method.…”

Section: Introductionmentioning

confidence: 99%

Time-resolved measurement of optical emission line profiles from electron cyclotron resonance ion source plasma

Timonen,

Koivisto,

Kronholm

et al. 2024

J. Phys.: Conf. Ser.

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Optical emission spectroscopy provides a non-invasive method to probe the properties of hot and highly charged magnetically confined plasmas. The optical emission line profiles enable, for example, to identify the different species and characterize the relative population densities and temperatures of the ions and neutrals forming the plasma. The feasibility of this approach has been demonstrated at the University of Jyväskylä accelerator laboratory by measuring the light emitted by Electron Cyclotron Resonance Ion Source (ECRIS) plasma with a high-resolution spectrometer setup POSSU (Plasma Optical SpectroScopy Unit). In these previous studies, the emission line profiles were measured by scanning the desired wavelength range by rotating the diffraction grating of the spectrometer. This process is slow compared to many interesting plasma phenomena, thus limiting the applicability of the setup. Recently, POSSU has been upgraded by changing the light sensor from a photomultiplier tube to a position-sensitive imaging sensor. As a result, it is possible to measure simultaneously a 1 - 2 nm wavelength range, with a spectral resolution in the order of picometers, without moving the grating. This enables a time-resolved study of the optical emission line profiles. By turning the grating, the measured wavelength region can be chosen between 370 nm and 870 nm, which covers the visible light spectrum. The time-evolution of optical emission line profiles emitted from the JYFL 14 GHz ECRIS plasma, during shifting plasma conditions induced by changing the gas balance, has been measured to demonstrate this new capability. The time-evolution of temperatures and emission intensities of selected ion species, correlated with extracted ion beam currents, are presented.

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Space-resolved electron density and temperature evaluation by x-ray pinhole camera method in an ECR plasma

Finocchiaro,

Naselli,

Mishra

et al. 2024

Physics of Plasmas

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X-ray emission characterization provides valuable insights about electron cyclotron resonance (ECR) plasmas. In principle, space-resolved spectroscopic techniques can be used to reveal spatial distributions of electron density and temperature. In the PANDORA (Plasma for Astrophysics, Nuclear Decay Observation, and Radiation for Archaeometry) project framework, and within the collaboration between the Atomki and INFN-LNS laboratories, we developed a high-resolution full-field x-ray pinhole setup. This setup incorporates advanced analysis techniques for single photon counted imaging in high dynamical range mode, enabling x-ray imaging and space-resolved spectroscopy at high spatial and energy resolution (560 μm and 242 eV @ 8.1 keV, respectively). Here, we introduce an innovative technique for quantitatively evaluating the local electron density and temperature of plasma, as the first application of such a method in an ECR setup. Specifically, we examine an argon plasma heated by 200 W microwave power at 14 GHz. Our analysis includes a retrospective comparison with past x-ray data collected from other ECR ion source setups. Our findings clearly reveal the formation of a plasmoid–halo structure within the plasma chamber, characterized by a dense and hot plasma almost totally enclosed inside the ECR magnetic iso-surface (the plasmoid). This plasmoid exhibits nearly uniform distribution of electron density and temperature, with only gentle gradients of both the parameters toward its edges. Inside the halo, x-ray emission is minimal or even negligible. Notably, cusp structures correspond to magnetic branches where deconfined electrons impinge upon the plasma chamber walls and endplates. The average values of temperature and density measured inside the plasmoid are 12.44±1.84 keV and (1.66±0.15)×1017 m−3, respectively.

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Preface for the special topic on “ion source diagnostics”

Cited by 3 publications

References 15 publications

The Multi-Detectors System of the PANDORA Facility: Focus on the Full-Field Pin-Hole CCD System for X-ray Imaging and Spectroscopy

The Multi-Detectors System of the PANDORA Facility: Focus on the Full-Field Pin-Hole CCD System for X-ray Imaging and Spectroscopy

Time-resolved measurement of optical emission line profiles from electron cyclotron resonance ion source plasma

Space-resolved electron density and temperature evaluation by x-ray pinhole camera method in an ECR plasma

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