BaPSF Image Gallery

	A Projection of magnetic field lines onto the plane centered z=94.8 cm from the targets. The data were derived from vector magnetic field measurements taken on five planes at distances ranging from 31.5 to 284.4 cm from the targets. The time is 5.25 microseconds after the targets are struck. Magnetic field data in each plane were acquired at 900 spatial locations on a rectangular grid with 1 cm spacing in the x and y directions. The background magnetic field which goes out of the plane of the figure is not included. The field lines are colored according to the local magnetic field in G. Two reconnection regions are visible above and below the central current channel.
See papers related to this image: Three-dimensional current systems generated by plasmas colliding in a background magnetoplasma.

	A field line bundle composed of those field lines that pass near the upper reconnection region shown in Figure 8. The color bar is the same as that in Figure 8. The background magnetic field is in the z direction but is not included in this bundle. (a) is a global view looking away from the cathode plasma source. To help grasp the three-dimensional nature of the image, a semitransparent plane with white grid lines on a black surface is placed at z=95cm. Because of the transparency, field lines appear grayed if they are beneath the grid lines and are darker beneath the open areas. Field lines above the plane are unaffected. The gray grid lines are spaced at 5 cm intervals and are centered at z = 95 cm. Data were acquired at 1 cm intervals everywhere in the transverse plane. Note in (b) that the field lines span both sides of the grid, and near the reconnection point have a substantial out-of-plane component.
See papers related to this image: Three-dimensional current systems generated by plasmas colliding in a background magnetoplasma.

	A three-dimensional view of the instantaneous magnitude of the magnetic field of an Alfvén wave, measured in the LArge Plasma Device. The wave propagates primarily in the direction of the ambient magnetic field, but there is also cross-field propagation of wave energy until the wave reaches the radial boundary of the plasma. Alfvén waves with small cross-field structure, such as the one visualized in this image have electric fields parallel to the background field and therefore can accelerate electrons. This mechanism is thought to play a key role in the formation of the earth’s aurora [See Wygant, et al., JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 105, NO. A8, doi:10.1029/1999JA900500, 2000]
See papers related to this image: http://plasma.physics.ucla.edu/bapsf/papers/IEEE_cyclotron_waves.pdf http://plasma.physics.ucla.edu/bapsf/papers/Vincena_PRL_2004.pdf Contact: vincena@physics.ucla.edu for more information.

	Whistler waves are launched from a small loop antenna which then propagate into a carefully created density striation (field-aligned, cylindrical depletion in plasma density.) The waves undergo a linear conversion to lower hybrid waves with a much shorter perpendicular wavenumber but with a large electric field which can then heat the plasma ions. Using carefully scaled dimensionless parameters, this experiment recreates the essential physics of a process which occurs in the earth’s ionosphere.
See papers related to this image: http://plasma.physics.ucla.edu/bapsf/papers/Bamber_jgr.pdf

	The instantaneous vector wave magnetic field produced by two interacting Alfvén waves. The wave propagates from left to right and the relative phase of the two waves is such that they constructively interfere at the center of the plasma column, producing a perturbation of delta-B/B = 10^-3.
See papers related to this image: http://plasma.physics.ucla.edu/bapsf/papers/Budapest_paper.pdf

	This is a snapshot of the time-varying magnetic field measured in a plane perpendicular to the background magnetic field within the plasma of LAPD. In this experiment, high-power microwaves are directed from outside of the chamber, through a window, and into the plasma. The microwaves are incident from y=0 and x=-50cm. They heat the plasma in a narrow region at the edge (x=-20cm) producing a field-aligned burst of electrons (a current channel) which shows up as a circulation of the magnetic field vectors.

	Image of a helium discharge tube being used to calibrate a laser-induced fluorescence diagnostic. The output of a narrow band (500MHz) dye laser is directed into pink glow of hot helium neutrals. Only when the frequency of the laser is tuned to match a specific atomic transition does the yellow line in the middle of the image (and a reflection from the glass tube) become visible.

	Current streamlines of a shear Alfvén wave launched by a helical antenna. The wave magnetic field on a plane orthogonal to the background magnetic field is shown to guide the eye. For this wave, the parallel current is carried by the electrons and the perpendicular current is carried by the ions.
See papers related to this image: http://plasma.physics.ucla.edu/bapsf/papers/Budapest_paper.pdf

	Streamlines of current from an azimuthally symmetric Alfvén wave, launched by modulating a current filament with transverse size on the order of the electron collisionless skin depth (and the ion-sound gyroradius: cs/wci). This wave is at a frequency close to the ion-cyclotron frequency, so that the ExB drifts of the ions and electrons no longer cancel exactly and the wave develops both an oscillating azimuthal electric field and axial magnetic field.
This image appears in an article accepted for publication in the IEEE Transactions on Plasma Science, Special Issue: Images in Plasma Science, 2005, authors: Vincena and Gekelman. See also, http://plasma.physics.ucla.edu/bapsf/papers/beach_pop.pdf Contact: vincena@physics.ucla.edu for more information.

	The currents of Alfven waves with several "m" numbers rendered as snakes.
This image appears in an article accepted for publication in the IEEE Transactions on Plasma Science, Special Issue: Images in Plasma Science, 2005, authors: Gekelman and Vincena

	Time-averaged wave energy density around a cylindrical density cavity for a single frequency (f = 6 times the lower hybrid frequency). The top panel shows the energy density and with contours. The middle panel shows the density gradient in fill; and the energy density contours from the top panel to allow an easy comparison. The bottom panel shows a line-cut across y = 0.0 cm. The striation diameter is 2.5 cm.
See papers related to this image: http://plasma.physics.ucla.edu/bapsf/papers/JGR_Lower_Hybrid.pdf

	Upper plate: Streamlines (in the perpendicular plane) of the wave magnetic field of two interacting shear Alfvén waves, along with isosurfaces of the axial current density. Lower plate: Close up of the instantaneous wave magnetic field vectors for the indicated plane. The plasma source (a heated, oxide-coated cathode) is visible in the upper, right-hand corner of the image.
See papers related to this image: http://plasma.physics.ucla.edu/bapsf/papers/Budapest_paper.pdf

	This is an additional image from an experiment on the interaction of two Alfvén waves. Data were acquired on a plane 2.64 meters from a helical antenna. The magnetic vector field is color coded in accord with the field strength. Data were acquired at each location that an arrow is drawn. The background magnetic field is directed into the page.
See papers related to this image: http://plasma.physics.ucla.edu/bapsf/papers/Budapest_paper.pdf

	Creation of drift waves by the controlled depletion of plasma electrons in a flux tube intersecting a circular, current collecting copper mesh. Upper panel: measurement of the density cavity via ion saturation current collected by a probe in a perpendicular plane located 1.6 meters axially away from the current collecting "antenna", along with a computer-generated representation for reference. Lower panel: two instantaneous measurements of the density perturbation of the m=-1 drift wave which exist along the steepest density gradient of the depletion, along with the "antenna" for reference.
See papers related to this image: http://plasma.physics.ucla.edu/bapsf/papers/Budapest_paper.pdf Contact: vincena@physics.ucla.edu for more information.

	This image is a representation of the product of radius and wave current density (rj) for an Alfvén wave, at one instant in time. The vector current density is calculated for the case with electron plasma beta = 6.8(m_electron/m_ion). The source is located at z _ 0, r _ 0, and has a 0.5 cm radius. The centers of the vortices are located 1.25 m or lambda/2 apart.
See papers related to this image: http://plasma.physics.ucla.edu/bapsf/papers/lenemanprl.pdf

	This perspective image was created from measurements of the magnetic field in the case of constructive interference of two Alfvén cones. The magnitude is shown as a semi-transparent surface with an embedded vector field. For referenc e, the vectors are also displayed in an orthogonal projection.

	Two intertwined magnetic flux tubes.
See papers related to this image: W. Gekelman, J.M. Urrutia, R.L. Stenzel, Measurement of Magnetic Helicity During the Disruption of a Neutral Current Sheet, from Magnetotail Physics, edited A.T. Lui, Johns Hopkins University Press, pp 261-274, (1987)

	The three dimensional merging of electrical currents in a plasma.
See papers related to this image: W. Gekelman, J. Maggs, H. Pfister, Experiments on the Interaction of Current Channels in a Laboratory Plasma: Relaxation to a Force Free State, IEEE Trans. Plasma Sci., 20,614-621 (1992).

	The computed distribution function of electrons during an interaction with a wave.

	The violent disruption of a sheet of current.

	Tearing of a thin current sheet.
See papers related to this image: W. Gekelman, H. Pfister, Experimental Observations of the Tearing of an Electron Current Sheet, Phys. Fluids, 31, 2017-2025 (1988).

	The transmission response function of a directional velocity analyzer.

	This is a display of the magneic field (arrows) and two isosurfaces (blue and green) of a shear Alfven wave. The data is rendered inside a scale model of the machine (the LAPD {Large Plasma Device}) that the data was acquired in. A shear Alfven wave launched from an oscillating current on the scale of the electron skin depth. The wave magnetic field is shown as arrows. The magnitude of the wave is shwon in cigar shaped isosurfaces. They are hollow since the wave intensity is zero on axis. The antenna which launches the waves is shown on the extreme right. Also shown is the cathode and a cutaway of the magnets which surround the vacuum vessel.
See papers related to this image: W. Gekelman, S. Vincena, D. Leneman, J. Maggs, "Laboratory Experiments on Shear Alfven waves and their relationship to space plasma", JGR, 102, 7225-7236 (1997)

	The oxide coated cathode shown at emission temperature. The cathode was designed to emit over 20 kA in magnetic fields of up to 4 kGauss.

	Shear Alfven wave in Argon shown on six planes. In this experiment the wave magnetic field was measured at 30,000 spatial locations (and several thousand time steps) on 16 planes. There are 2,000 measurement locations at each plane. Red shows the highest wave intensity.

	A Helium Plasma viewed through an end port.

	This is a photograph of the elements of a tunable dye-laser used for a laser-induced fluorescence (LIF) diagnostic. On the optical table, the output of the pump laser (Coherent Innova 400 Argon Ion Laser) is steered with optics into the smaller ring dye laser cavity (Coherent 899-29) which produces a narrow band (500MHz) output which is then delivered to the plasma device using a fiber optic cable (not shown).