Principles of Plasma Diagnostics

Hutchinson, I. H.

doi:10.1017/cbo9780511613630

Cited by 1,132 publications

(735 citation statements)

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“…The experiments were carried out using a standard, circular, slightly unbalanced, In this work Rogowski coils [16] were used for measuring the current density. The probe consists of a helical coil of wire with the lead from one end returning through the centre of the coil to the other end, so that both terminals are at the same end of the coil in order to eliminate contributions from other components of the current.…”

Section: Methodsmentioning

confidence: 99%

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Internal current measurements in high power impulse magnetron sputtering

Lundin

Sahab

Brenning

et al. 2011

Plasma Sources Sci. Technol.

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The transport of charged particles in a high power impulse magnetron sputtering (HiPIMS) discharge is of considerable interest when optimizing this promising deposition technique with respect to deposition rate and control of the ion acceleration. In this study the internal current densities Jφ (azimuthal direction) and Jz (axial direction) have therefore been spatially and temporally resolved in the bulk plasma region above a cylindrical magnetron using Rogowski coils. From the measurements a phenomenological model has been constructed describing the evolution of the current density in this pulsed plasma. The core of the model is based on three different types of current systems, which characterize the operating transport mechanisms, such as current transport along and across magnetic field lines. There is a gradual change between these current systems during the initiation, build-up and steady state of a HiPIMS plasma. Furthermore, the data also show that there are spatial and temporal variations of the key transport parameter Jφ/Jz, governing the cross-B resistivity and also the energy of the charged particles. The previously reported faster-than-Bohm cross-B electron transport is verified here, but not for all locations. These results on the plasma dynamics are essential input when modeling the axial electric field, governing the back-attraction of ionized sputtered material, and might furthermore provide a link between the different resistivities reported in HiPIMS, pulsed-DC, and DC magnetron discharges.

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Section: Methodsmentioning

confidence: 99%

“…Furthermore, the probe and rod could be rotated in order to measure directional currents. In the present investigation the axial as well as azimuthal current profiles were determined in the region 48 z  cm and A Rogowski coil produces a voltage signal [16] given as…”

Section: Methodsmentioning

confidence: 99%

Internal current measurements in high power impulse magnetron sputtering

Lundin

Sahab

Brenning

et al. 2011

Plasma Sources Sci. Technol.

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“…4. Additionally, in the low collision energy regime the total CX cross-section scales like σ cx,tot,lowE ∝ n D 4 , while the intermediate collision energy regime scales oppositely 25 , σ cx,tot,intE ∝ 1 (n D ) 3 . These three charge-exchange attributes at low collision energy (preferential excited state n ′ res of receiver, narrow n ′ -distribution of partial CX cross-section, and increasing total CX cross-section with n D ) lead to the excited neutrals playing a much more significant photon generating role in GP-CXRS than in highenergy beam CXRS.…”

Section: Charge Exchange Of Impurities With Neutrals From a Gas mentioning

confidence: 99%

“…Deriving Doppler spectrometry quantities of radiance, velocity, and temperature from the GP-CXRS signal proceeds as in any other CXRS system: remove passive light contributions from the spectra, use a computational non-linear regression analysis to derive the moments of the spectra (taking care to remove instrument function and Zeeman effects 40 ), then relate these moments with their physical quantities 25 . Example profiles are shown in Fig 14 for an EDA Hmode 41 .…”

Section: Analysis Of Spectramentioning

confidence: 99%

Development of the gas puff charge exchange recombination spectroscopy (GP-CXRS) technique for ion measurements in the plasma edge

Churchill

Theiler

Lipschultz

et al. 2013

Review of Scientific Instruments

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A novel charge-exchange recombination spectroscopy (CXRS) diagnostic method is presented, which uses a simple thermal gas puff for its donor neutral source, instead of the typical high-energy neutral beam. This diagnostic, named gas puff CXRS (GP-CXRS), is used to measure ion density, velocity, and temperature in the tokamak edge/pedestal region with excellent signal-background ratios, and has a number of advantages to conventional beam-based CXRS systems. Here we develop the physics basis for GP-CXRS, including the neutral transport, the charge-exchange process at low energies, and effects of energy-dependent rate coefficients on the measurements. The GP-CXRS hardware setup is described on two separate tokamaks, Alcator C-Mod and ASDEX Upgrade. Measured spectra and profiles are also presented. Profile comparisons of GP-CXRS and a beam based CXRS system show good agreement. Emphasis is given throughout to describing guiding principles for users interested in applying the GP-CXRS diagnostic technique.

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“…The interferometry method using electromagnetic waves is useful and convenient to obtain a line-integrated plasma density [1] and can be used in the high density plasma more than 10 20 m −3 , where it is difficult to measure the plasma density by an electrostatic probe. The MPDA plasma density had been measured by an interferometry method using a CO 2 laser [2] or a dual-beam laser [3].…”

Section: Inroductionmentioning

confidence: 99%

A Multi-Reflection Type Visible-Laser Interferometer for High Density Plasma Measurements

Hattori

Noguchi

Andõ

et al. 2007

Plasma and Fusion Research

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In order to measure a high density plasma more than 10 20 m −3 in the vicinity of a magneto-plasma-dynamic arcjet (MPDA), a visible-laser interferometer is fabricated using a He-Ne laser (λ = 632.8 nm). As it doesn't have enough phase shift when the light passes through the MPDA plasma once, we adopt a multi-reflection optical system in this interferometer to improve the phase sensitivity. We measured a plasma density by the interferometer and estimated the maximum value of line-integrated density of 4 × 10 19 m −2 . These experimental results are consistent with that of electrostatic probe measurement in the downstream region. Keywords: laser interferometer, multi-reflection, magnet-plasma-dynamic arcjet, high density plasma, electron density measurement DOI: 10.1585/pfr.2.S1048 InroductionA magneto-plasma-dynamic arcjet (MPDA) is utilized as a high-enthalpy plasma source not only for a plasma injection source for open magnetic confinements but for an electric propulsion and several applications. Detailed measurement of plasma density in the vicinity of an MPDA is important to evaluate its performance.The interferometry method using electromagnetic waves is useful and convenient to obtain a line-integrated plasma density [1] and can be used in the high density plasma more than 10 20 m −3 , where it is difficult to measure the plasma density by an electrostatic probe. The MPDA plasma density had been measured by an interferometry method using a CO 2 laser [2] or a dual-beam laser [3]. However, the interferometer was not always used as an electron density measurement method and detail measurement has not been achieved yet.The purpose of this research is to develop a laser interferometer for measurement of a high density plasma in the vicinity of an MPDA. The feature of this interferometer is to use a He-Ne laser (λ = 632.8 nm) and a multi-reflection optical system. A He-Ne laser is easily obtained and easy to handle as visible light. As it doesn't have enough phase shift when the light passes through the MPDA plasma once, we adopt a multi-reflection optical system in this interferometer to improve the phase sensitivity. Interferometer SystemA Schematic of the Michelson-type interferometer system is shown in Fig. 1, where a He-Ne laser (10 mW) is used as a light source. The laser beam is divided into a reference beam and a probe beam by a beam splitter (BS).author's e-mail: hattori@nit.ac.jp The probe beam is reflected between a corner cube mirror and a flat mirror with a convex lens and passes through a plasma many times. The multi-reflection optical system was developed by D. Lee et al. for the purpose of a high accuracy displacement measurement [4]. One of the additional advantages in this system is that the number of reflection can be easily changed. We used the concept of the optical system to utilize the plasma measurement method. However, the spatial resolution is rather poor because the average values of the integrated line density along with an optical path is obtained. A mockup experiment was attempted i...

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Principles of Plasma Diagnostics

Cited by 1,132 publications

References 0 publications

Internal current measurements in high power impulse magnetron sputtering

Internal current measurements in high power impulse magnetron sputtering

Development of the gas puff charge exchange recombination spectroscopy (GP-CXRS) technique for ion measurements in the plasma edge

A Multi-Reflection Type Visible-Laser Interferometer for High Density Plasma Measurements

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