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Plasma Wave

NSSDCA ID: 1972-073A-11

Mission Name: IMP-H
Principal Investigator:Dr. Frederick L. Scarf


Electric field components perpendicular to the spacecraft spin axis and the magnetic field component parallel to that axis were measured by an electric dipole antenna and a search coil magnetometer. Both sensors were mounted on a 3.05-m boom. Data were obtained in eight frequency channels from 10 Hz to 100 kHz in either the normal mode or the snapshot mode. Two channels, centered at 67 and 600 Hz, had 10-dB fall-off points of 17 and 150 Hz, and 270 and 810 Hz, respectively. The remaining six channels were narrow-bandwidth channels centered at 1.3, 2.3, 5.4, 10.5, 30, and 70 kHz. In the normal mode, the antenna was first sampled in a given frequency channel many times during a given measurement period (comparable to the spacecraft spin period). During the next period, the search coil was sampled many times in the same frequency channel. Next, the antenna was sampled in the next frequency channel, followed by the search coil in that channel. The frequency channels were incremented, and the sampled sensors were alternated until a full set of data was obtained in 16 measurement periods (approximately 20 s). In the snapshot mode, only electric field data were transmitted, as follows. The antenna was first sampled in a given frequency channel many times during a given measurement period. In the next period, the antenna was sampled in two sequences of eight frequency channels. This two-period measurement was executed eight times, each time incrementing the frequency channel studied in every other period by one. Thus, a full set of data again required 16 measurement periods. In addition, an analog mode, sampling the antenna and search coil from 10 to 100 Hz, was used in conjunction with the special purpose analog telemetry test that was to be conducted. Unfortunately, this telemetry system did not work well, and no usable data were obtained in this mode of operation. For the digital modes, some interference was experienced from the asymmetric plasma sheath associated with the solar cell arrays. This interference limited the sensitivity of the magnetic field measurements and introduced complexity into analysis of the electric field measurements. Data from IMP-I are recommended by the PI to be used whenever possible.

Alternate Names

  • IMP-H/PlasmaWave
  • Plasma Wave Experiment

Funding Agency

  • NASA-Office of Space Science (United States)


  • Space Physics: Magnetospheric Studies
  • Space Physics: Heliospheric Studies

Additional Information

Questions and comments about this experiment can be directed to: Dr. H. Kent Hills



NameRoleOriginal AffiliationE-mail
Dr. Robert W. FredricksOther InvestigatorTRW Systems Group
Dr. Ira M. GreenOther InvestigatorTRW Systems Group
Mr. Gaines M. CrookOther InvestigatorGaines M. Crook Associates
Dr. Frederick L. ScarfPrincipal InvestigatorTRW Systems Group
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