A transient partially ionized plasma has been observed by two-wavelength holographic interferometry. Electron-density measurements of plasmas that are less than fully ionized are possible by use of this diagnostic technique.
Barium plasma was injected into the northern magnetospheric cleft twice during January, 1975. Lofted by rockets launched after local magnetic noon from Cape Parry, NWT, Canada, high‐explosive shaped charges compressed hollow barium cones to generate vapor jets moving upward with initial velocities near 13 km/s parallel to the geomagnetic field. Barium plasma streaks created by solar photoionization of the vapor were convected through the polar magnetosphere and were observed optically from airborne and ground‐based sites until about 40 min after injection. Numerous indicators were monitored to determine the degree of magnetospheric disturbance; ionosondes at Cape Parry and Sachs Harbour, NWT, monitored latitudinal cleft motions preceding rocket launch. Spectrometers in the payloads recorded charged‐particle fluxes during both flights. The first injection occurred poleward in the cleft with subsequent plasma convection antisunward across the polar cap; the second occurred centrally with plasma convection duskward at constant magnetic latitude.
Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation R. A. Jeffries, L. B. Seely, R. G. Fowler; Influence of the End Plate on Shock Reflection in the High‐Explosive Shock Tube. Physics of Fluids 1 August 1964; 7 (8): 1390–1391. https://doi.org/10.1063/1.1711390 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAIP Publishing PortfolioPhysics of Fluids (PFL) Search Advanced Search |Citation Search
Holographic interferometry can be applied to plasmas whose density results in shifts of less than one fringe by superposing the small shifts on an arbitrarily shaped and positioned background fringe pattern. The sensitivity of holographic interferometry is thereby increased to that of conventional interferometry, while the inherent advantages of holography are retained. The background fringes also simplify detection of the spurious phase changes that can arise in holography from motions of the apparatus.
In January 1975, two barium plasma injection experiments were carried out with rockets launched from Cape Parry, Northwest Territories, Canada, into the upper atmosphere where field lines from the dayside cusp region intersect the ionosphere. One experiment, Tordo 1, took place near the beginning of a worldwide magnetic storm. It became a polar cap experiment almost immediately as convection perpendicular to B moved the fluorescent plasma jet away from the cusp across the polar cap in an antisunward direction. Convection across the polar cap with an average velocity of more than 1 km/s was observed for nearly 40 min until the barium flux tubes encountered large E fields associated with a poleward bulge of the auroral oval near Greenland. Prior to the encounter with the aurora near Greenland there is evidence of upward acceleration of the barium ions while they were in the polar cap. The three‐dimensional observations of the plasma orientation and motion give an insight into convection from the cusp region across the polar cap, the orientation of the polar cap magnetic field lines out to several earth radii, the causes of polar cap magnetic perturbations, and parallel acceleration processes.
