Vorticity probes and the characterization of vortices in the Kelvin-Helmholtz instability in the large plasma device experiment

Journal Article · Tue Feb 01 04:00:00 EST 2005 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.1830489· OSTI ID:20698328

Horton, W; Perez, Jean C; Carter, Troy; Bengtson, Roger ^[1]

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1. Institute for Fusion Studies, University of Texas at Austin, Austin, Texas 78712 (United States)

A new five-pin probe design called the vorticity probe is presented that explicitly measures the vorticity in the ExB flow from floating potentials, independent of any absolute calibration errors. The five Tantalum probe tips are arranged in a diamond pattern with 5 mm tip spacing. The fluctuating floating potential at each tip is measured and used to compute a finite-difference approximation of the ExB vorticity. The probe is tested in the large plasma device (LAPD) [W. Gekelman et al., Rev. Sci. Instrum. 62, 2875 (1991)], operated with a variable bias between the anode and the chamber wall that creates a sharply localized E{sub r} profile at 30 cm from the axis of the 100 cm diameter chamber. The fluctuations are peaked in the shear flow layer and are correlated with theoretical calculations of the Kelvin-Helmholtz instability for this plasma. The spectrum at 15-30 kHz matches the theoretical prediction from the measured dE{sub r}/dr gradient that reaches 17 kV/m{sup 2} in the B=0.075 T axial magnetic field.

• OSTI ID: 20698328
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 2 Vol. 12; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
FINITE DIFFERENCE METHOD
FLUCTUATIONS
HELMHOLTZ INSTABILITY
LANGMUIR PROBE
MAGNETOHYDRODYNAMICS
PLASMA
VORTICES