Howell, S. K. | Engineering Papers

NASA NTRS1993

Programmable Multiple-Ramped-Voltage Power Supply

Ramp waveforms range up to 2,000 V. Laboratory high-voltage power-supply system puts out variety of stable voltages programmed to remain fixed with respect to ground or float with respect to ramp waveform. Measures voltages it produces with high resolution; automatically calibrates, zeroes, and configures itself; and produces variety of input/output signals for use with other instruments. Developed for use with ultraviolet spectrometer. Also applicable to control of electron guns in general and to operation of such diverse equipment used in measuring scattering cross sections of subatomic particles and in industrial electron-beam welders.

Ajello, Joseph M.↗

NASA NTRS1989

A study of electron impact excitation of NO. I - The vacuum ultraviolet from 40 to 170 nm. II - The middle ultraviolet from 170 to 270 nm

The electron impact induced fluorescence spectrum of NO at 200 eV was measured for the vacuum UV range (40-170 nm) and the mid-UV range (170-270 nm). The absolute electron impact excitation cross sections are studied by calibrating to the Ly-alpha cross section of H2. The cross section of the N I 120-nm transition by dissociative excitation is found to be 1.73 + or - 0.38 X 10 to the -18th sq cm. Measurements of the cross sections of other features in the vacuum UV and mid-UV are presented. A band model of the far-UV (120-170 nm) is developed. Also, it is found that great care must be taken if NO is the target for relative calibration in the Mid-UV using the molecular branching ratio techniques.

Ajello, J. M.↗