Engineering topics

Labelle, J.

Publications and source records attributed to Labelle, J..

23 records · Page 2

NASA NTRS1986

Argon ions injected parallel and perpendicular to the magnetic field

Preliminary results are reported of measurements obtained with the 0-10-kHz electric-field plasma-wave receivers and single-particle ion detectors of the ARCS-3 sounding-rocket payload over the auroral oval on February 10, 1985, after downward/field-parallel or transverse-spiral injection of Ar ions from the accelerator subpayload (separating itself at 2.3 m/s). The data are presented graphically and briefly characterized. The waves induced by the parallel injections are found to be much weaker than those induced by the perpendicular injections. In addition to the expected response to the Ar beam, an ion flux at pitch angle 90 deg was detected during the second parallel injection.

Erlandson, R. E.↗

NASA NTRS1986

A comparison of plasma waves produced by ion accelerators in the F-region ionosphere

Ion beams injected into the ionosphere are known to produce waves related to the normal modes of the plasma. The spectra of plasma waves produced during four sounding rocket experiments are examined. The experimental conditions were somewhat different during each experiment. The accelerated ion was either Xe(+) or Ar(+) and the experimental geometry, described by the separation vector between the plasma wave receiver and the ion accelerator, was either parallel or perpendicular to the geomagnetic field.

Kintner, P. M.↗

NASA NTRS1985

Absolute electron density measurements in the equatorial ionosphere

Accurate measurement of the electron density profile and its variations is crucial to further progress in understanding the physics of the disturbed equatorial ionosphere. To accomplish this, a plasma frequency probe was included in the payload complement of two rockets flown during the Condor rocket campaign conducted from Peru in March 1983. This paper presents density profiles of the disturbed equatorial ionosphere from a night-time flight in which spread-F conditions were present and from a day-time flight during strong electrojet conditions. Results from both flights are in excellent agreement with simultaneous radar data in that the regions of highly disturbed plasma coincide with the radar signatures. The spread-F rocket penetrated a topside depletion during both the upleg and downleg. The electrojet measurements showed a profile peaking at 1.3 x 10 to the 5th per cu cm at 106 km, with large scale fluctuations having amplitudes of roughly 10 percent seen only in the upward gradient in electron density. This is in agreement with plasma instability theory. It is further shown that simultaneous measurements by fixed-bias Langmuir probes, when normalized at a single point to the altitude profile of electron density, are inadequate to correctly parameterize the observed enhancements and depletions.

Baker, K. D.↗

NASA NTRS1985

Mapping of electric field structures from the equatorial F region to the underlying E region

The theories of electrostatic fields in the equatorial ionosphere attributed to Farley (1960) and Spreiter and Briggs (1961) are reviewed, and a hybrid of these theories is applied to investigate how spread F irrregularities map down to the underlying E region. It is found that structures larger than 1 km map easily through the E region, while smaller structures do not. This implies that in general, subkilometer F region irregularities cannot directly generate image striations in the underlying E region, a result which affects previous investigations of the role of images in equatorial spread F.

Labelle, J.↗

NASA NTRS1984

Interferometric phase velocity measurements

Phase velocities of plasma waves near the lower hybrid frequency were measured with an interferometer composed of two spatially separated electron-density probes. The plasma waves were produced in the F-region ionosphere by an argon ion beam. By calculating the normalized cross spectrum of the plasma waves a coherency of .98 was estimated along with a maximum phase difference of pi/3 radians between the two probes. This implies that the wavelength was 6 meters compared to an O(+) gyroradius of 3.8 meters, and that the phase velocity was 45 km/sec compared to an ion-beam velocity of 12.4 km/sec. These numbers compare favorably with recent predictions of a nonresonant mode produced by a dense ion beam.

Kintner, P. M.↗