Measurements of electron density and temperature in the H-1 heliac plasma by helium line intensity ratios

Ma, Songde; Howard, J.; Blackwell, Boyd; Thapar, N.

doi:10.1063/1.3692756

Cited by 23 publications

(21 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Big progress on the CRM had been bade by Brosda and co-authors [4], leading to the first application of a thermal helium beam in a fusion plasmas in the TEXTOR experiment in 1992 [5]. Helium line ratio spectroscopy can be applied on background helium as done in MST [6], NAGDIS-II [7], ASDEX Upgrade [8], heliac devices [9,10] and the FT-2 tokamak [11]. For bigger devices, improved spatial resolution can be achieved by actively injecting helium into the plasma either by a supersonic beam [12] as done in TEXTOR [13] and TJ-IU [14].…”

Section: Introductionmentioning

confidence: 99%

Qualification and implementation of line ratio spectroscopy on helium as plasma edge diagnostic at ASDEX Upgrade

Griener

Burgos

Cavedon

et al. 2017

Plasma Phys. Control. Fusion

View full text Add to dashboard Cite

A new thermal helium beam diagnostic has been implemented as plasma edge diagnostic at the ASDEX Upgrade (AUG) tokamak. The helium beam is built to measure the electron density n e and temperature T e simultaneously with high spatial and temporal resolution in order to investigate steady-state as well as fast transport processes in the plasma edge region. For the thermal helium beam emission line ratio spectroscopy, neutral helium is locally injected into the plasma by a piezo valve. This enabled the measurement of the line resolved emission intensities of seven He I lines for different plasma scenarios in AUG. The different line ratios can be used together with a collisional-radiative model (CRM) to reconstruct the underlying electron temperature and density. Ratios from the same spin species are used for the electron density reconstruction, whereas spin mixed ratios are sensitive to electron temperature changes. The different line ratios as well as different CRMs are tested for their suitability for diagnostic applications. Furthermore their consistency in calculating identical parameters is validated and the resulting profiles are compared to other available diagnostics at AUG.

show abstract

Section: Introductionmentioning

confidence: 99%

Qualification and implementation of line ratio spectroscopy on helium as plasma edge diagnostic at ASDEX Upgrade

Griener

Burgos

Cavedon

et al. 2017

Plasma Phys. Control. Fusion

View full text Add to dashboard Cite

show abstract

“…This emission is strongly related to electron density fluctuations and weakly related to electron temperature fluctuations at typical H-1NF electron temperatures. Future work based on the ratio of tomographically inverted atomic helium transitionline emission contours at a number of wavelengths will allow absolute measurement of both the electron density and temperature fluctuations [14,15] for comparison with theoretical predictions [16,17].…”

Section: Introductionmentioning

confidence: 99%

Visible light tomography of MHD eigenmodes in the H-1NF stellarator using magnetic coordinates

Haskey¹,

Blackwell²,

Seiwald³

et al. 2014

Nucl. Fusion

View full text Add to dashboard Cite

A tomographic reconstruction technique is described for the inversion of a set of limited-angle high-resolution 2D visible light emission projections of global MHD eigenmodes in the H-1NF heliac. The technique is well suited to limited viewing access in toroidal devices and the strong shaping of optimized stellarator/heliotron configurations. Fluctuations are represented as a finite sum of Fourier modes characterized by toroidal and poloidal mode numbers having fixed amplitude and phase in a set of nested flux volumes in Boozer coordinates (Boozer 1980 Phys. Fluids 23 904-8). Iterative tomographic inversion techniques and standard linear least-squares methods are used to solve for the complex amplitudes. The method is applied to synchronous camera images of singly charged carbon impurity ion emission at 514 nm obtained at three discrete poloidal viewing orientations (Haskey et al 2014 Rev. Sci. Instrum. 85 033505). The 2D amplitude and phase projections provide high quality reconstructions of the radial structure of the fluctuations that are compact in Boozer space and allow clear determination of the poloidal mode number as well as some degree of toroidal mode number differentiation.

show abstract

“…The relatively cool electron temperatures in these plasmas means that carbon ion emission at 514nm is radiated from all regions in the plasma, making it suitable for revealing the structural details of the mode, through its dependence on impurity ion density, electron density (n e ) and electron temperature (T e ). Analysis of photon emissivity using ADAS models [26] shows an insensitivity to changes in electron temperature when T e > 25eV, which is typically the case for a large portion of the plasma on H-1NF [27]. Therefore, the tomographic inversions of the intensity fluctuations presented in this paper are closely related to changes in the electron density.…”

Section: Data Used In the Tomographic Reconstructionsmentioning

confidence: 64%

3D Tomography of MHD Fluctuations in the H-1NF Heliac

Haskey,

Blackwell,

Seiwald

et al. 2014

Preprint

View full text Add to dashboard Cite

A 3D tomographic reconstruction technique is described for inversion of a set of limited-angle high-resolution 2D visible light emission projections (extended in the vertical and toroidal directions) of global MHD eigenmodes in the H-1NF heliac. This paper deals with some of the features and challenges that arise in the application of tomographic imaging systems to toroidal devices, especially limited viewing access and the strong shaping of optimised stellarator/heliotron configurations. The fluctuations are represented as a finite sum of Fourier modes characterised by toroidal and poloidal mode numbers having fixed amplitude and phase in a set of nested cylindrical flux volumes in Boozer space[1]. The complex amplitude is calculated using iterative tomographic inversion techniques such as ART, SIRT and standard linear least-squares methods. The tomography is applied to synchronous camera images of singly charged carbon impurity ion emission at 514nm obtained at three discrete poloidal viewing orientations [2]. It is shown that the 2D amplitude and phase projections provide high quality reconstructions of the radial structure of the fluctuations that are compact in Boozer space and allow clear determination of the poloidal mode number as well as some degree of toroidal mode number differentiation.

show abstract

Measurements of electron density and temperature in the H-1 heliac plasma by helium line intensity ratios

Cited by 23 publications

References 28 publications

Qualification and implementation of line ratio spectroscopy on helium as plasma edge diagnostic at ASDEX Upgrade

Qualification and implementation of line ratio spectroscopy on helium as plasma edge diagnostic at ASDEX Upgrade

Visible light tomography of MHD eigenmodes in the H-1NF stellarator using magnetic coordinates

3D Tomography of MHD Fluctuations in the H-1NF Heliac

Contact Info

Product

Resources

About