Accession Number : AD0272628

Title :   DOPPLER MEASUREMENT OF THE IONIZED WAKES OF HYPERVELOCITY PELLETS

Corporate Author : MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB

Personal Author(s) : RICHARDSON,R.E. ; HERLIN,M.A.

Report Date : MAY 1961

Pagination or Media Count : 1

Abstract : This L-band doppler experiment employs hypervelocity pellets traveling axially through a rectangular waveguide with matched terminations, excited at 1200 Mcps. The measured return due to the pellet alone agrees with the computed value. At re-entry speeds, observation of enhancementAND DOPPLER SHIFTS OF THE RETURN GIVES INFORMATION ON WAKE IONIZATION, TURBULENCE, ELECTRON TRAIL LENGTH, AND ON THE SLOWING DOWN OF THE WAKE. In low-pressure air, the wake is composed of two types of reflection: a short-portion traveling at the velocity of the pellet, and a longer portion traveling much slower than the pellet. The signals from the two portions have comparable magnitudes, considerably greater than that of a pellet alone. Similar electronic circuitry is used simultaneously to measure properties of the signal transmitted axially through the waveguide containing the wake. The results are used to infer propagation properties through the wake at L-band frequencies. (Author)

Descriptors :   *DOPPLER SYSTEMS, *HYPERVELOCITY PROJECTILES, *RADIO SIGNALS, *RADIOFREQUENCY SPECTROSCOPY, *SPECTRUM ANALYZERS, *WAKE, ALUMINUM, ELECTROMAGNETIC RADIATION, ELECTRONIC EQUIPMENT, HYPERVELOCITY GUNS, INSTRUMENTATION, IONIZATION, MEASUREMENT, NYLON, OSCILLOSCOPES, PHASE SHIFT CIRCUITS, STORAGE TANKS, THERMAL RADIATION, WAVE PROPAGATION, WAVEGUIDES

Distribution Statement : APPROVED FOR PUBLIC RELEASE