Abstract: A method for manufacturing a miniature quadrupole from a single blank includes fastening four lengthwise insulating strips into parallel slots formed in the blank. A lengthwise axial hole is cut through the blank for the guide wire used in the EDM process. The blank is machined lengthwise into four electrodes using the EDM process so that the electrodes are spaced apart in a widthwise direction and each electrode is connected to an adjacent electrode by one of the insulating strips. During the cutting, the electrodes are held in place by the insulating strips.

Abstract: A miniaturized ion source for a mass spectrometer includes a anode and a focus plate whose interior surfaces form an ionization volume for a retained gas sample. Molecules of the gas sample are ionized by electrons, and the resulting ions are concentrated and converged through an exit aperture in the focus plate to the entrance of an ion analyzer, such as a quadrupole mass filter. Preferably, at least one of the anode and the focus plate includes a curved interior surface which converges the formed ions into a focused beam for directing into the ion analyzer. In addition, the thickness of the exit aperture of the focus plate and or the setback of the focus plate relative to the anode ensures that no line of sight exists between the interior surface of the anode from which ion-forming electrons can scatter into the adjacent ion analyzer.

Abstract: A mass spectrometer gas analyzer includes an ion source for producing ions of a sample gas in a defined ion volume. An ion analyzer collects and analyzes a first portion of the produced ions to determine a partial pressure for a selected gas species within the sample gas. An oppositely disposed ion collector collects a second portion of the ions to determine a total pressure of the contained gas sample. A collecting surface of the ion collector is positioned relative to the incoming ion beam to allow collection of ion current but the surface is configured such that a substantial portion of a plurality of secondary electrons produced by ion bombardment with the ion collector are deflected away from the ionization volume. The partial pressure is thus determined by the ion analyzer without secondary electrons entering the ion analyzer.

Abstract: A dual beam ion source comprises an ion volume in an ion chamber, an ion collector, and two identical ion accelerators. One ion accelerator accelerates a first, "test" ion stream from the ion volume in a first direction and directs it to the ion collector where it can be directly measured. The second ion accelerator accelerates a second, "utilizable" ion stream from the ion volume in a second direction. By directly measuring the ion current (caused by the first, "test" ion stream) at the ion collector, either or both the total ion pressure of the gas within the ion volume, and the magnitude of the second, "utilizable" ion stream, can be calculated.

Abstract: An acoustic cell includes multiple acoustic cavities fluidly coupled together. At least two of the acoustic cavities have unequal lengths and cross sections. End segments of the acoustic cell are uniformly cylindrically shaped or conically shaped. A driver transducer at one end of the acoustic cell and a receiver transducer at another end of the acoustic cell are acoustically isolated from the acoustic cell. A pair of preferably metallic isolation diaphragms transmit acoustic signals to and from the transducers without significantly altering the phase-frequency characteristics of the acoustic signals. The acoustic cell operates as an acoustic resonator operating at frequencies lower than any possible self-resonance frequencies of the isolation diaphragms or the driver and receiver transducers. When a binary gas is flowed through the cell, a processor detects a resonant frequency of the gas within the cell to determine a composition of the gas.

Abstract: For treating a fluid sample for introduction to a mass spectrometer or other appropriate use, a composite membrane and support assembly allows analytes from a sample flow to permeate through a membrane free from the undesired background matrix. The composite membrane and support assembly comprises a semipermeable membrane, a fiber member for supporting the membrane, and a rigid perforated member for supporting the membrane and the fiber support.

Abstract: An acoustic technique is employed to identify the species of a sample of refrigerant gas and whether it contains significant contaminants. The refrigerant is admitted into a Helmholtz resonator under controlled pressure, and a drive frequency is swept across a frequency band and applied to a first transducer. A second transducer picks up the vibrations in the resonator and the output signal is compared to the drive signal. The resonant peak or center frequencies are identified and the sharpness or quality factors are measured. These measured data are compared with stored data to identify the refrigerant.

Abstract: An acoustic technique is employed to identify the species of a refrigerant gas and whether it contains significant contaminants. Air in the refrigerant can be tolerated, but must be accounted for in determining the acoustic properties of the sample. The refrigerant is admitted into a Helmholtz resonator under a controlled pressure, and a drive frequency is applied to a transducer. Another transducer picks up the vibrations in the resonator and an output signal is compared to the drive signal to find resonant peaks and sharpness factors. The change in resonant frequency with pressure is measured, and is employed to quantify the presence of air in the sample. The amount of air present determines a frequency correction, which permits unambiguous identification of the species of refrigerant and of its purity.

Abstract: A gas analyzing system that includes a vacuum chamber containing a mass spectrometer and a sampling device for introducing a gas sample into the chamber. A sorption pump is operatively connected to the chamber which is capable of maintaining the chamber at a high vacuum. The pump includes a diffusion barrier that provides smooth pumping characteristics and repeatable short term system behavior when sample pulses are introduced into the system.

Abstract: A sorption pump for high vacuum applications that is suited for use in gas analyzers such as mass spectrometers. The pump includes a housing containing a quantity of getter material and a diffusion barrier in the gas inlet to the housing. A finite period of time is required for gas molecules in the vacuum analyzer system to cross the barrier, thus providing a window during which gas pulses can be accurately analyzed.

Abstract: A miniaturized, portable sensor is provided for selectively sensing the presence of halogenated gases, particularly HFC's, within an atmosphere. The apparatus includes a ceramic element containing either a mixture of potassium silicate and either aluminum oxide or silicon dioxide which react with ions of the halogenated gas when the two are brought together forming a depletion layer on and within the ceramic. The sensor is formed with two electrodes on opposite sides of the ceramic having terminals connected into a circuit for detecting a potential difference across the depletion layer. Means are provided for detecting the potential differences and for producing a discernable signal in response thereto.

Abstract: An AT-cut quartz crystal for a quartz crystal microbalance has a buffer layer sandwiched between an adhesion layer and an electrode layer on the front or deposition side of the crystal. The buffer layer can be a zinc layer of 6000 .ANG. sandwiched between a titanium or chromium adhesion layer of 100 to 160 .ANG. and a gold, silver, or aluminum outer electrode layer of about 2000 .ANG.. The zinc layer has a relatively low bulk modulus, and absorbs stress imposed by the deposited layer. The buffer layer prolongs useful crystal life, particularly when depositing dielectric materials. The crystal should have a modest surface roughness as keying-in structure.

Abstract: A molecular spectrometer is provided that performs Fourier analysis utilizing the discrete Fourier Transform on a digitized time domain waveform that relates to the composition of a sample. Digitized reference waveforms are employed to permit the instrument to limit its analysis to frequencies of interest and thereby increase the rapidity of the analysis. Data at differing frequencies can be resolved at independent resolutions, and the instrument can analyze spectroscopic data in real time.

Abstract: An exposure control circuit captures an X-ray generator exposure time for a master exposure and replicates that time for subsequent exposures in a series. In one preferred circuit an read counter bank counts down clock pulses during the master exposure time, and then this count is held and is used by a write counter bank which counts up during subsequent exposures. A control circuit controls loading an enabling functions of the read and write counters. For the subsequent exposures, an output relay circuit terminates the X-ray generator exposure when the write counter bank reaches a predetermined count. This arrangement is used favorably with digital subtractive angiography (DSA).

Abstract: A monitoring circuit monitors a piezoelectric crystal for changes in its resonant frequency as a film of material is vacuum deposited on it, e.g. to control a source of vapors of the material. A controllable frequency generator generates a drive signal of a accurately known frequency and phase within a band of RF frequencies that includes the resonant frequency of the crystal. The RF signal is applied through a duplexing circuit to the crystal, and a response signal is applied through the duplexing circuit to a signal amplifier and limiter circuit to a phase detector. The phase detector is also supplied with the RF drive signal, and has a phase output signal which is zero when the crystal is at resonance, and is negative or positive when the applied RF signal is below or above resonance, respectively.

Abstract: The thickness and rate of growth of a deposited film is monitored using a piezoelectric crystal sensor such as an AT-cut plano-convex crystal. The frequencies of the fundamental frequency and another resonance mode are measured prior to deposition, and the change of these two frequencies is monitored during deposition. The areal mass density of the deposited material is determined from these two resonance frequencies for the uncoated quartz crystal and for the crystal during deposition. A frequency generator provides accurate sweeps of frequency which are applied to the crystal, and the crystal response is supplied to a phase detector to identify the positions of the resonance frequencies. The acoustic impedance ratio Z of the deposited material relative to the fresh crystal is computed from the resonance frequencies for the coated and uncoated crystal, by applying the modal equations for AT-cut plano-convex quartz crystal and Lu-Lewis relation.

Abstract: A sensor for selectively sensing the presence of halogenated gases, particularly HFC's, within an atmosphere. The apparatus includes a ceramic element containing either a mixture of alkali metal silicates and aluminum oxide or aluminosilicate which react with ions of the halogenated gas when the two are brought together forming a depletion layer on and within the ceramic. A preferred ceramic composition is a mixture of potassium slicate and either one of silicon dioxide or aluminum oxide. The sensor is formed with two electrodes on opposite sides of the ceramic having terminals connected into a circuit for detecting a potential difference across the depletion layer. Means are provided for detecting the potential differences and for producing a discernable signal in response thereto.

Abstract: A multiple crystal head has aluminum rotary carousel within an aluminum body, and number of crystals disposed about the axis of the carousel. A water line coil is clamped to the aluminum body by a stainless steel clamp plate, and a beryllium copper finger spring provides thermal contact between the carousel and the body so that any heat from the deposition process is quickly removed by the water coil. A space is maintained between the front of the carousel and the proximal side of the body front face so that there is no scraping when the carousel rotates. A removable stainless steel heat shield over the body provides good thermal isolation and prevents deposits from reaching the aluminum body or other parts behind the shield. A pneumatic bellows and a pawl and ratchet assembly rotate the carousel to bring the various crystals into the active, monitoring position.

Abstract: A radiation therapy imager provides images of a patient while being treated while on a radiation therapy machine for purposes of verification and monitoring of position and alignment, and for shaping of the radiation field. The radiation therapy imager has a video camera mounted on the gantry of the radiation therapy machine and positioned diametrically opposite the treatment head. An elongated light box is disposed over the camera to exclude ambient light from the camera and a fluoroscopic plate is positioned at the distal end of the light box, i.e., the end remote of the camera. The plate is aligned with and facing the head to produce a fluoroscopic image in response to the treatment radiation that is applied from the head through the patient. A mirror in the light box is oriented to reflect the image to the camera to permit monitoring on a viewing screen. The light box can be retracted from under the treatment table either by telescoping the light box down or by swinging the light box to one side.

Abstract: An optical partical pressure gas analyzer employs an electron beam to excite the outer electrons of gas atoms or molecules, and one or more photomultiplier tubes or other similar detectors to detect wavelengths of photons characteristic of the decay of the outer electrons of one or more species of gas molecules. The photomultiplier tubes have a viewing direction substantially at right angles to the electron beam. A Faraday trap or similar device is employed to minimize secondary electron generation. This-film interference filters are favorably employed to pass a specific characteristic wavelength of the desired species, and to reject other wavelengths. An electromechanical filter changer permits each photomultiplier tube to analyze and identify many gaseous species in the low pressure mixture.