Spatial distribution of the plasma parameters in the RF negative ion source prototype for fusion

Lishev, St.; Schiesko, L.; Wünderlich, D.; Fantz, U.

doi:10.1063/1.4916452

Cited by 19 publications

(31 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It should be noted that although the ⃗ E × ⃗ B drift plays an important role, the total plasma drift is more complex and consists of several components -theoretical models indicate that in addition the diamagnetic drift plays an important role for the plasma transport through the magnetic filter. 8,15,16 Although neutral Cs is distributed homogeneously in the source during plasma phases 17 , the plasma drift might affect the vertical distribution of Cs + ions due to a higher rate of ionization collisions in drift direction. A so called bias plate (same potential as the source body) covers the area of the PG where no extraction apertures are positioned and thus increases the area on source potential.…”

Section: Introductionmentioning

confidence: 99%

Extraction of negative charges from an ion source: Transition from an electron repelling to an electron attracting plasma close to the extraction surface

Wimmer

Fantz

NNBI-Team³

2016

Journal of Applied Physics

View full text Add to dashboard Cite

Large-scale sources for negative hydrogen ions, capable of delivering an extracted ion current of several ten amperes, are a key component of the neutral beam injection system of the upcoming ITER fusion device. Since the created heat load of the inevitably co-extracted electrons after magnetic separation from the extracted beam limits their tolerable amount, special care must be taken for the reduction of coextracted electrons -in particular in deuterium operation, where the larger amount of co-extracted electrons often limits the source performance. By biasing the plasma grid (PG, first grid of the extraction system) positively with respect to the source body the plasma sheath in front of the PG can be changed from an electron repelling towards an electron attracting sheath. In this way, the flux of charged particles onto the PG can be varied, thus changing the bias current and inverse to it the amount of co-extracted electrons. The PG bias affects also the flux of surface-produced H − towards the plasma volume as well as the plasma symmetry in front of the plasma grid, strongly influenced by an ⃗ E × ⃗ B drift. The influence of varying PG sheath potential profile on the plasma drift, the negative hydrogen ion density and the source performance at the prototype H − source is presented, comparing hydrogen and deuterium operation. The transition in the PG sheath profile takes place in both isotopes, with a minimum of co-extracted electrons formed in case of the electron attracting PG sheath. The co-extracted electron density in deuterium operation is higher than in hydrogen operation, which is accompanied by an increased plasma density in deuterium.

show abstract

Section: Introductionmentioning

confidence: 99%

Extraction of negative charges from an ion source: Transition from an electron repelling to an electron attracting plasma close to the extraction surface

Wimmer

Fantz

NNBI-Team³

2016

Journal of Applied Physics

View full text Add to dashboard Cite

show abstract

“…2(a)) is a 2D planar geometry description in the (y-z)-plane which is perpendicular to the direction of the magnetic field lines (Fig. 2(b)) [8]. However, due to the finite scales of the driver and the expansion plasma volume in the third x-direction, the losses of particles and energy along it may also plays a role in the formation of the discharge structure.…”

Section: Formulation Of the Problem And Set Of Equationsmentioning

confidence: 99%

“…In a view of performance of the sources, the main role of the magnetic filter (MF) is to reduce, both, the electron temperature and the current of the co-extracted electrons by means of a transverse magnetic field. However, the magnetic field introduces significant modifications in the spatial structure of the plasma parameters [3][4][5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

“…Studying different type of the MF (i.e., the configuration of the MF of ELISE) as well as taking into account for the presence of a magnetic field in the driver are issues not addressed yet in the models applied for the RF prototype source [6][7][8]. Accounting for the charged particle and energy losses along the magnetic field lines is another issue, starting to be considered in the PIC-codes, but not taken into account in the 2D−fluid−models.…”

Section: Introductionmentioning

confidence: 99%

“…Although it does not introduce qualitative changes in the pattern of the plasma parameters [5], the fluxes along the FF could reduce significantly the fluxes in the transverse direction, where the 2D models are applied. Involving the complicated geometry of the prototype source without accounting for the FF in the driver [6][7][8] shows the known [5] pattern of the plasma parameters. However, in the previous model [8] it was identified that effects of the plasma expansion into the bigger volume of the second chamber are superimposed on the effects of plasma expansion through the MF as well as shifting the entire discharge pattern in correlation with the shift of the position of the filter.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Influence of the configuration of the magnetic filter field on the discharge structure in the RF driven negative ion source prototype for fusion

Lishev

Schiesko

Wünderlich

et al. 2017

AIP Conference Proceedings

Self Cite

View full text Add to dashboard Cite

Abstract.The study provides results of the influence of the filter field topology on the plasma parameters in the RF prototype negative ion source for ITER. A previously developed 2D fluid plasma model has been extended to take into account for the particles and energy losses along the magnetic field lines and the presence of a magnetic field in the driver as it is the case for the BATMAN and ELISE test-beds. Since the main role of the magnetic filters in these two sources is the same (to reduce the co-extracted electron current) they are studied and compared for the geometry of the prototype source. For the magnetic field configuration used at BATMAN, the axial position of the filter has been varied according to experiments with an external magnet frame. For the magnetic field configuration of ELISE the magnitude of the field has been varied, as can be done in the experiment by varying the current flowing through the first grid of the extraction system. The obtained results show the same main features in the patterns of the plasma parameters for the two configurations of the magnetic filter. The presence of a magnetic filter in the driver has a local impact on the plasma parameters, showing no significant influence on their spatial distributions in the expansion chamber.

show abstract

Improved understanding of beamlet deflection in ITER-relevant negative ion beams through forward modelling of Beam Emission Spectroscopy

Hurlbatt

Harder

Fantz

2020

Fusion Engineering and Design

View full text Add to dashboard Cite

show abstract

Spatial distribution of the plasma parameters in the RF negative ion source prototype for fusion

Cited by 19 publications

References 14 publications

Extraction of negative charges from an ion source: Transition from an electron repelling to an electron attracting plasma close to the extraction surface

Extraction of negative charges from an ion source: Transition from an electron repelling to an electron attracting plasma close to the extraction surface

Influence of the configuration of the magnetic filter field on the discharge structure in the RF driven negative ion source prototype for fusion

Improved understanding of beamlet deflection in ITER-relevant negative ion beams through forward modelling of Beam Emission Spectroscopy

Contact Info

Product

Resources

About