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Northrop, T. G.

Publications and source records attributed to Northrop, T. G..

52 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

On Greenstadt's binary index criterion.

The Greenstadt-type criterion for distinguishing between laminar and 'pulsating' (i.e., irregular) bow shock crossings can be expressed as a critical angle between the shock normal and the magnetic field. When the field is more tangent to the shock plane than this critical angle, the shock is laminar. More importantly, the requirement of Galilean invariance of the physics underlying such a criterion reveals that the Greenstadt p index must vary inversely as the solar wind velocity.

Northrop, T. G.↗
NASA NTRS1972

On Greenstadt's binary index criterion

The Greenstadt-type criterion for distinguishing between laminar and pulsating (i.e., irregular) bow shock crossings can be expressed as a critical angle between the shock normal and the magnetic field. When the field is more tangent to the shock plane than this critical angle, the shock is laminar. More importantly, the requirement of Galilean invariance of the physics underlying such a criterion reveals that the Greenstadt p index must vary inversely as the solar wind velcoity.

Northrop, T. G.↗
NASA NTRS1972

Study of waves in the earth's bow shock.

Results of an examination of the perturbation vectors of waves upstream and downstream from the region of maximum compression in the bow shock on Ogo 5 under particularly steady solar-wind conditions. The polarization of the upstream waves was right-hand circular, and that of the downstream waves left-hand elliptical in the spacecraft frame. By observing that the polarization of the waves remained unchanged as the shock motion swept the wave structure back and forth across the satellite three times in eight minutes, it was found that the waves were not stationary in the shock frame. A study of the methods of determining the shock normal indicates that the normal estimated from a shock model should be superior to the normal based on magnetic coplanarity. The propagation vectors of the waves examined did not coincide with the shock-model normal, the average magnetic field, or the plasma-flow velocity. However, the major axis of the polarization ellipse of the downstream wave was nearly parallel to the upstream propagation vector.

Holzer, R. E.↗
NASA NTRS1971

A study of waves in the earth's bow shock

The perturbation vectors of waves up and downstream from the region of maximum compression in the bow shock were examined on OGO-5 under particularly steady solar wind conditions. The polarization of the upstream waves was RH, circular and of the downstream waves LH, elliptical in the spacecraft frame. By observing that the polarization of the waves remained unchanged as the shock motion swept the wave structure back and forth across the satellite three times in eight minutes, it was found that the waves were not stationary in the shock frame. A study of the methods of determining the shock normal indicates that the normal estimated from a shock model should be superior to one based upon magnetic coplanarity. The propagation vectors of the waves examined did not coincide with the shock model normal, the average magnetic field, or the plasma flow velocity. However, the major axis of the polarization ellipse of the downstream wave was nearly parallel to the upstream propagation vector.

Holzer, R. E.↗