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Full-Text Articles in Plasma and Beam Physics
The Magnetopause: Bringing Space Physics Into A Junior Lab, Jim Crumley, Ari Palczewski,, Stephen Kaster
The Magnetopause: Bringing Space Physics Into A Junior Lab, Jim Crumley, Ari Palczewski,, Stephen Kaster
MapCores Faculty Publications
Undergraduate students often have minimal exposure to many subfields
of physics which are active areas of research. Space physics
is an area that is particularly difficult to expose students to since
it builds off of another area that most undergraduates see little of,
plasma physics. The magnetopause is convenient entry point
into space physics, since it can be modeled as a pressure balance, which is
a concept familiar from introductory physics. We use the Earth's
magnetopause as the basis for a lab for junior physics majors. In
the lab students analyze results from a NASA MHD simulation and
data from …
Ion Acceleration In A Helicon Source Due To The Self-Bias Effect, Matt Wiebold, Yung-Ta Sung, John E. Scharer
Ion Acceleration In A Helicon Source Due To The Self-Bias Effect, Matt Wiebold, Yung-Ta Sung, John E. Scharer
Physics Faculty Publications
Time-averaged plasma potential differences up to 165 V over several hundred Debye lengths are observed in low pressure (pn < 1 mTorr) expanding argon plasmas in the Madison Helicon eXperiment (MadHeX). The potential gradient leads to ion acceleration greater than that predicted by ambipolar expansion, exceeding Ei≈7 kTe in some cases. RF power up to 500 W at 13.56 MHz is supplied to a half-turn, double-helix antenna in the presence of a nozzle magnetic field, adjustable up to 1 kG. A retarding potential analyzer (RPA) measures the ion energy distribution function (IEDF) and a swept emissive probe measures the plasma potential. Single and double probes measure the electron density and temperature. Two distinct mode hops, the capacitive-inductive (E-H) and inductive-helicon (H-W) transitions, …
Experimental Observation Of Ion Beams In The Madison Helicon Experiment, Matt Wiebold, Yung-Ta Sung, John E. Scharer
Experimental Observation Of Ion Beams In The Madison Helicon Experiment, Matt Wiebold, Yung-Ta Sung, John E. Scharer
Physics Faculty Publications
Argon ion beams up to Eb=165 eV at Prf=500 W are observed in the Madison Helicon eXperiment (MadHeX) helicon source with a magnetic nozzle. A two-grid retarding potential analyzer (RPA) is used to measure the ion energy distribution, and emissive and rf-filtered Langmuir probes measure the plasma potential, electron density, and temperature. The supersonic ion beam (M=vi/cs up to 5) forms over tens of Debye lengths and extends spatially for a few ion-neutral charge-exchange mean free paths. The parametric variation of the ion beam energy is explored, including flow rate, rf power, and …
Observations Of Neutral Depletion And Plasma Acceleration In A Flowing High-Power Argon Helicon Plasma, C. Mark Denning, Matt Wiebold, John E. Scharer
Observations Of Neutral Depletion And Plasma Acceleration In A Flowing High-Power Argon Helicon Plasma, C. Mark Denning, Matt Wiebold, John E. Scharer
Physics Faculty Publications
Neutral depletion effects are observed in a steady-state flowing argon helicon plasma with a magnetic nozzle for high rf input powers (up to 3 kW). Noninvasive diagnostics including 105 GHz microwave interferometry and optical spectroscopy with collisional-radiative modeling are used to measure the electron density (ne), electron temperature (Te), and neutral density (nn). A region of weak neutral depletion is observed upstream of the antenna where increasing rf power leads to increased electron density (up to ne = 1.6×1013 cm-3) while Te remains essentially constant and …