Abstract: A method and gas analysis system for a mass spectrometer including an ion pump for creating an internal vacuum within said mass spectrometer, an ionization chamber, an inlet passage through which a gas sample is introduced into the ionization chamber, valve means associated with the inlet passage for controlling the volume of gas sample introduced into the ionization chamber, a filament for introducing electrons into the ionization chamber whereby the electrons bombard the gas sample thus forming ions, an extractor plate positioned adjacent the ionization chamber and biased such that a proportion of ions and electrons are allowed to pass through the extractor plate, a quadrupole filter into which the ions and electrons are directed by the extractor plate, the quadrupole filter operative to permit a stream of ions with a pre-selected mass-to-charge ratio to pass through the filter and ions other than those having the pre-selected mass-to-charge ratio being separated from the stream of ions, means for directing

Abstract: A frequency to voltage converter including input terminals for receiving a stream of pulses with either fixed or variable time intervals between pulses, means for producing a voltage that varies as an inverse function of the time interval between the pulses applied thereto, first means responsive to the pulses of the stream of pulses for sampling the voltage output of the voltage producing means, and second means responsive to the pulses of the stream of pulses for applying input pulses to the voltage producing means subsequent to the sampling of the voltage output thereof by the first means whereby each sample voltage output of the sampling means is proportional to a frequency corresponding to a time interval between sequentially applied pulses.

Abstract: In an interlaced pulse-echo and range-gated Doppler system, an ultrasound transmitter generates a train of constant repetition rate echo pulse interlaced with a Doppler pulse train of plural bursts. The time duration between each burst and the preceding range gate opening is held constant while the time to the successive range gate opening is automatically varied to provide a continuously variable PRF tracking of the console range gate depth setting. The power of the transmitted signal is internally varied in the same sense and the cutoff frequency of the receiver low pass tracking filters is varied in the opposite sense to optimize signal-to-noise ratio at various tissue inspection depths. Selectable turnable high pass filters normalized to low velocity roll-off eliminate artifact for peripheral or central vascular probes. The detection system operates in quadrature and includes a synchronous demodulator and a peak detector, and a level detector operative on peak detected signals.

Abstract: A method and inlet control system for controlling a gas flow sample to an evacuated chamber such as found in a mass spectrometer, is disclosed. The system utilizes a short inlet passage having an effective opening determined by a tapered diamond or steel tip needle adjacent to the inlet passage. The needle is positionally adjusted with respect to the inlet passage by being mounted on a piezoelectric crystal which is flexed by coupling thereto an electric potential derived by sensing the ions at the ionization chamber of a mass spectrometer, for example, and developing therefrom an electric signal indicative of the total pressure within the ionization chamber. The signal coupled to the piezoelectric crystal is preferably a pulse-width modulated signal with the needle maintaining the inlet passage closed except during the time that the piezoelectric crystal is flexed due to a received pulse.