Abstract: A microliter-sized metastable ionization device with a cavity, a sample gas inlet, a corona gas inlet and a gas outlet. A first electrode has a hollow and disposed in the cavity and is in fluid communication with the sample gas inlet. A second electrode is in fluid communication with the corona gas inlet and is disposed around the first electrode adjacent the hollow end thereof. A gap forming means forms a corona gap between the first and second electrodes. A first power supply is connected to the first electrode and the second power supply is connected to the second electrode for generating a corona discharge across the corona gap. A collector has a hollow end portion disposed in the cavity which is in fluid communications with the gas outlet for the outgassing and detection of ionized gases. The first electrode can be a tubular member aligned concentrically with a cylindrical second electrode. The gap forming means can be in annular disc projecting radially inwardly from the cylindrical second electrode.

Abstract: A plasma monitoring and control method and system monitor and control plasma in an electronic device fabrication reactor by sensing the voltage of the radio frequency power that is directed into the plasma producing gas at the input to the plasma producing environment of the electronic device fabrication reactor. The method and system further sense the current and phase angle of the radio frequency power directed to the plasma producing gas at the input to the plasma producing environment. Full load impedance is measured and used in determining characteristics of the plasma environment, including not only discharge and sheath impedances, but also chuck and wafer impedances, primary ground path impedance, and a secondary ground path impedance associated with the plasma environment. This permits end point detection of both deposition and etch processes, as well as advanced process control for electronic device fabrication.

Abstract: The present invention relates to a method for measuring an ion flow from a plasma to a surface in contact therewith, consisting of measuring the rate of discharge of a measuring capacitor connected between a radiofrequency voltage source and a plate-shaped probe in contact with the plasma.

Abstract: A sample solution contained in a sample vessel is analyzed using a positive ion detector and a negative ion detector. The positive ion detector and the negative ion detector are supplied with the sample solution from the sample vessel, while isolating the positive ion detector and the negative ion detector from one another. Accordingly, the sample solution is not supplied from the positive ion detector to the negative ion detector, and the sample solution is not supplied from the negative ion detector to the positive ion detector. The positive ion detector and negative ion detector are preferably supplied with sample solution from the sample vessel using a bidirectional valve having an input port and first and second output ports. The input port is connected to the sample vessel, the first output port is connected to the first detector, and the second output port is connected to the second detector.

Abstract: A method and apparatus for the detection of trace constituents in inert gases. Three modes of operation of the said invention are most preferred. In the first embodiment, a dielectric barrier discharge cell receives an inert gas, excites the gas, and the gas is then allowed to mix with additional gas in which the constituent to be measured is entrained. Energy is then passed from the excited states of the inert gas to the analytes of interest creating charged analytes of interest which are then measured through the use of commercial electrometers. In a second embodiment, the dielectric barrier discharge device receives the analyte entrained within the inert gas and the gas and, in some cases, the analytes are excited. The excited species then pass on and any resulting ionized species are then detected through the use of an electrometer.

Abstract: In a discharge ionization detector, a method and apparatus are disclosed for increasing the transfer of photons and metastables from a discharge chamber to a ionization chamber, while effecting ion discrimination of the ionic current with respect to a signal cathode, thereby reducing the effect of ionic current in the signal output. Preferred embodiments of the invention include a discharge source located in a discharge chamber, means for introducing discharge gas flow into the discharge chamber, a flow guide that directs discharge gas flow between the discharge chamber and an adjacent ionization chamber, and inlet port for introducing a flow of sample gas containing an analyte into the ionization chamber and an outlet port for exhausting the sample gas and the discharge gas. A plurality of apertures in the flow guide are situated proximate the discharge source so as to promote the rapid and efficient transfer of photons and metastables from the discharge source into the ionization chamber.

Abstract: Apparatus for directly measuring the value of a component within an RF circuit (e.g., an RF matching network within a semiconductor wafer processing system). Specifically, the apparatus applies a low frequency signal (e.g., a 1 KHz) across one or more of the components within an RF circuit using a bridge circuit that is sufficiently isolated from the RF signal to accomplish accurate measurements of the component. The apparatus monitors the amplitude of the low frequency signal across the component. The amplitude of the low frequency signal is indicative of the value of the component.

Abstract: According to a method and an apparatus for determining absolute plasma parameters in unsymmetrical radio frequency (RF) low-pressure plasmas, a radio frequency discharge current generated in a plasma reactor is measured in the form of analog signals at a portion of the reactor acting as earth electrode, the analog signals are converted into digital signals, and the desired plasma parameters are evaluated from the digital signals by means of a mathematical algorithm. The apparatus includes a meter electrode which is insulatedly positioned in a flange or recess of the reactor wall which acts at least as part of the earth electrode. The method and apparatus may be used with respect to plasma etching in the technical field of the semiconductor technology.

Abstract: The proposed method of carrying out diagnostics on a process for the thermo-chemical treatment of steels and alloys in a glow discharge involves monitoring the ionization characteristics of the atmosphere as revealed by the intensity of the electromagnetic radiation in various frequency intervals. The proposed device for carrying out the method in question comprises a primary converter (1) in the form of an electromagnetic radiation emitter unit and contains filtering elements (5) mounted in such a way that they can be positioned in the radiation zone in front of the receiver (6) on a rotating disk (4). The disk (4) is provided with a rotation drive (7) for positioning the elements (5).

Abstract: A detection system measures very small concentrations of compounds of interest within gaseous samples. A spark discharge system induces pulsed spark discharges across a pair of electrodes within an inert gas in a gas flow chamber. Various reactions are induced by spark interaction with the flow of inert gas, and with any sample or dopant commingled with the inert gas, in the region of the pulsed spark discharge. This induces photon ionization which creates an instantaneous current flow within the gas flow chamber. Current flow is held constant for all concentrations of sample introduced into the gas flow by means of a control feedback system. The output of the control feedback system is indicative of sample concentration. The system responds linearly over approximately five orders of magnitude of sample concentration for use with the sample which will be described and low femtogram sensitivity is achieved.

Abstract: A plasma density monitor is described for determining the ion current of a plasma flowing through a conduit (14). The monitor comprises a plate (18) having a face and an orifice extending from the face through the plate. The internal surface of the orifice conforms with the internal surface of the conduit when the face is adjacent the conduit. The monitor also comprises a detector circuit (22) for sensing the ion current collected by the internal surface of the plate (18). Another embodiment monitors plasma density by determining electrical conductivity in the afterglow of a microwave induced plasma. A resonant LC circuit (50, C3) has a multi-turn coil (C3) surrounding the conduit, an RF oscillator circuit (54, 56) for driving the LC circuit, and a circuit (64, 66, 68, 70, 72, 76) for measuring the decay time of the LC circuit. Plasma flowing through the conduit alters the resistivity of the coil and the time constant of the LC circuit proportional to the electrical conductivity of the flowing plasma.

Abstract: In accordance with the method of the present invention, the radio frequency discharge current generated in a plasma reactor is measured in the form of analog signals at a portion of the reactor acting as an earth electrode. The analog signals are converted into digital signals, and plasma parameters are evaluated from the digital signals by means of a mathematical algorithm.

Abstract: This instrument can measure parameters of a plasma accurately and easily even though the plasma is exited by a high-frequency. The instrument for measuring parameters of a plasma generated in a vacuum chamber by high-frequency discharge at a given frequency comprises a wire (106) for electrically connecting a first electrode (101) arranged in a space where a plasma is produced and a terminal (110) arranged outside the vacuum chamber for taking out signals, and a first insulator (105) so arranged as to cover at least a part of the surface of the wire therewith. The absolute value of the impedance at the given frequency between the first electrode and the ground when looking into the terminal side from the first electrode is five times or more the absolute value of the impedance at the given frequency between the first electrode and the plasma in a state where no direct current flows through the first electrode.

Abstract: A method and apparatus for accurately characterizing the electron density and distribution of a confined plasma on the basis of high-frequency, broadband electromagnetic measurements is disclosed herein. The technique involves noninvasive, broadband measurement of electromagnetic transmission through a plasma. In one implementation, multivariate analysis techniques are employed to correlate features of the resultant spectra with plasma characteristics such as electron density or electron distribution. Alternately, such techniques are used to correlate the resultant spectra with parameters relating to conditions under which the plasma is generated. More specifically, the quantitative plasma characterization technique involves generating a set of broadband calibration spectra by measuring transmission of electromagnetic energy through a calibration plasma. Each broadband calibration spectrum is obtained using a different set of reference parameters being related to predefined quantitative characteristics.

Abstract: A device for the selective detection of a component from a gas mixture comprises a selective prefilter for retaining the other components of the gas mixture, a measuring unit arranged downstream of the selective prefilter for the component to be detected, and a pump pumping the gas mixture. The use of a photoionization detector as a downstream measuring unit makes possible a continuous display operation.

Abstract: For measuring the charge transported in an ion or electron beam, collecting grids are provided in a cascaded manner and the galvanic currents occurring there are measured. The same surface range is measured on the collecting cascade with respect to the particle current in the vacuum. The process and apparatus have particular applicability in partial-pressure and total-pressure measuring apparatuses, e.g. mass spectrometers and Bayard-d'Alpert tubes.

Abstract: There is a method and disclosed apparatus for detecting for the presence within a gaseous atmosphere of a gas of a concentration above a preset level. The detecting apparatus comprises a sensor including a heater/anode element and a collector/cathode element disposed to define a space therebetween through which the gaseous atmosphere flows. An actuable power supply is coupled to the heater/anode element and to the collector/cathode element for applying power thereto, whereby ionization of the gas causes a current flow through the collector/cathode element of a magnitude proportional to the concentration level of the gas in the gaseous atmosphere. An actuable alarm means provides an indication of the presence of the gas above the preset level. Detecting apparatus control operates the detecting apparatus in a monitoring mode, wherein the power supply is actuated and the alarm deactuated to detect and compare the current flow with the preset level.

Abstract: A high voltage differential is applied across two separated electrodes by a oltage supply. Between these electrodes is located a sample of the solid propellant or other energetic material. The voltage differential across the electrodes generates a spark of measurable voltage, current and time duration in the sample in order to foretell at what energy level sustained ignition of the sample occurs. This spark is measured by a voltage monitor which, upon reaching a predetermined level, sends a signal to a short-circuiting network. The short-circuiting network, after a predetermined time delay, shorts the electrical path across the electrodes thereby removing the voltage differential across the sample and ending the ignition test. An operator is then able to determine visually whether or not the spark of known voltage, current and time duration has created sustained ignition of the sample material.

Abstract: A pulsed discharge photoinoization detector is set forth which comprises a plurality of closed chambers for receiving different types of carrier gas flowing there through between inlets and outlets. The carrier gases are exposed to a pair of electrodes forming a spark across each chamber and through each carrier gas. At least one component of each type of carrier gas is excited within each chamber by the spark discharges, and the resonance energies of each type of carrier gas are different. The sample to be analyzed is split and a portion is injected into each of the closed chambers where it is exposed to the excited carrier gases. Carrier gases, upon decay, serve as sources of ionizing radiation of differing energy which react with compounds within the sample gas producing ionization currents which are a function of the types of sample gas compounds and the types of carrier gases.

Abstract: An electrostatic decontamination method and decontamination device (10) is disclosed for decontaminating the surface of a semiconductor substrate. The decontamination device (10) includes particle ionizing device (24) that charges contaminating particles (26) on the surface of semiconductor substrate (16) thereby creating ionized particles. Decontamination device (10) also includes substrate biasing device (12) for creating a charge accumulation layer (14) at the top of semiconductor substrate (16) so that the charge accumulation layer (14) has the same charge sign as the ionized particles. In addition, the invention analytically characterizes particles using contaminating particle isolator (44) which contains a particle ionizing device (24) that charges contaminating particles (26) on the surface of semiconductor substrate (16) thereby creating ionized particles.

Abstract: A compact and low fuel consumption flame ionization detector includes a precisely pored metallic disk or a silicon micro-machined diffuser plate through which the sample gas tube extends a minimum distance (less than 2 mm). The oxidant flows into the detector in a direction parallel to a plane of the diffuser plate, passes into a small cavity under the diffuser, and then passes through a large number of very small holes formed in the diffuser plate before encountering the sample gas flow at the end of the gas tube. A narrow diameter collector is closely spaced to the end of the gas tube. The direction of feeding the air and the diffuser plate (which acts as a baffle) provide laminar flow and eliminate the flicker noise which would otherwise occur due to the air flow inlet being located very close to the gas tube end. The FID is vertically compact and operates at a high electric field strength, exceeding 90 V/mm.

Abstract: An improved ionizable gas or vapor detector device and method are provided which are capable in preferred forms of sampling 4.times.10.sup.-3 cubic meters or more of air sec.sup.-1 and are responsive to ionizable gas fluctuations at a rate of up to 100Hz. Use of the device of the present invention has proved to provide sensitivity to UV ionizable gas or vapor of over 500 times that of prior devices, giving detection of propylene tracer gas at concentrations of 2 parts per 1,000,000,000 and thus increasing the range from the gas source at which the device may be reliably used. Use for detection of leaks of volatile UV ionizable compounds and for monitoring processes where vapors are emitted is also provided.

Abstract: An apparatus for detecting a misfire in an internal combustion engine arranged so that a leak current caused when the insulation of an ignition plug is compensated. An ion current and the leak current can easily be discriminated from each other, whereby the ion current detection accuracy can be improved. The apparatus is provided with a biasing capacitor which is charged with a current flowing at the time of discharge through the ignition plug, a Zener diode for setting the voltage at which the capacitor is charged by this charging, a first semiconductor integrated circuit which detects the charging current flowing through the capacitor and thereafter outputs a control current through a predetermined time period, and which holds a peak value of a voltage converted from the ion current and detects the ion current by comparing the converted voltage value of the ion current and the held peak value.

Abstract: A photo-ionization detector utilizes an ultraviolet (UV) lamp and is designed for detecting and measuring the concentration of volatile gases flowing between closely spaced parallel electrodes. One of the electrodes is formed to allow photons to pass into the space between the electrodes to ionize the volatile gases between the electrodes. The detector also incorporates an improved ionization chamber.

Abstract: This invention is a method for determining when combustion cans or turbine blades are failing in gas turbine engines. It measures the specific ions emitted by hot spots of can and blade material when they have failed or are failing. The invention relies on the electromagnetic energy radiated by ions that are created as combustion gas erodes and ionizes the materials in these hot spots. Acceleration by the earth magnetic field and by acoustic and mechanical forces normally present in combustion machinery cause these charged particles to radiate identifiable electromagnetic emissions. The frequency of the radiation, being a function of the charge and mass of the particles, allows free ions in the exhaust stream to be identified. The device operates by measuring the electromagnetic spectrum and relating detected frequencies to the mass of the ions from can liner and blade materials. The device can be used in fixed installations such as power plants, ships and aircraft.

Abstract: The objective of the invention is a method for detection of alien matter contents in gas, in which method the gas and the substances contained in it are ionized in an ionization room (1). By the present methods impurities in gases cannot be determined fast and in small concentrations. In the method of the invention the ions contained in the gas are separated in a separation section (2) into positive and negative ions, of which at least the ions of either sign are led into a narrow analyzer channel (4). There, due to the capillary force, they are forced to move in the middle section of the channel, from where they are deflected by electric fields of different strength caused by different voltages (U1-U10) into an electrode located at the edge of the channel, where they cause ion current (I1-I10).

Abstract: A pulsed rare gas photoionization detector apparatus is set forth and incorporates a closed chamber for receiving a carrier gas flowing there through between inlets and outlets, and the carrier gas is exposed to a pair of electrodes forming a spark across the chamber and through the carrier gas. One component of the carrier gas is a dopant which selected from a plurality of rare gases. The sample to be analyzed is injected into the closed chamber where it commingles with the carrier gas. One reaction involves the formation of selected dopant in an excited state, which upon decay, serves as a source of ionizing radiation which reacts with sample compounds producing detectable events. These events are used to identify and quantify unknown compounds contained in the sample. The methods and apparatus are especially useful in selectively ionizing the compounds to be measured while not ionizing other constituents of the sample. This greatly enhances the signal-to-noise ratio for detecting impurity compounds.

Abstract: Generation and stabilization of glow plasma by discharge under atmospheric pressure are monitored by detection of the number of electric current pulses per one-half cycle of an alternating voltage applied to a discharge device. Alternately, or in addition, a Lissajous figure is generated showing a correlation between the applied alternating voltage and a current flow in the discharge device, and a discharge state is discriminated according to the Lissajous figure. Accurate, quick and simple monitoring of atmospheric pressure glow discharge plasma and the control thereof are thus made possible.

Abstract: A circular chamber is disclosed. Helium is introduced into the chamber to swirl in a circle to flow past a pair of spaced electrodes forming a spark in the helium. The chamber enables a sample detected by interaction with spark initiated ionization.

Abstract: An isolated detector for gas is set forth and incorporates a closed source chamber in cooperation with a sample chamber through which sample gas flows. Gas within the source chamber comprises Krypton which is excited to a metastable state by a pulsed, high voltage, direct current spark. Subsequent decay of metastable argon emits ionizing radiation which passes through a membrane window into the sample chamber thereby ionizing selected constituents within the sample gas. Charged particles resulting from the ionization of selected constituents are collected with voltage biased electrodes in the sample chamber, and the magnitude of the resulting current flow is related to the concentration of the ionized molecules or compounds. The apparatus for generating ionizing radiation requires no external source of gas, is rugged, is relatively inexpensive to manufacture and operate, and exhibits an operating life much longer than source lamps used in prior art devices.

Abstract: An apparatus for measuring ions in a gas which has a sensor around which the gas flows, the ions giving off their charge and giving rise to a current. The sensor is constructed as an electrode with a flow-favorable shape, such as a sphere. A fixed voltage is impressed on the electrode and the current produced at the electrode is measured, evaluated in a circuit and constitutes a measure for the ion count.

Abstract: An ionization gas analyzer system includes an ionization chamber including ionization electrodes contained therein. The ionization chamber contains a test gas or gas mixture. A high voltage generator is coupled to the electrodes and provides variable high voltage pulses to the ionization electrodes. An ionization voltage analyzer is coupled to the ionization chamber and receives ionization voltage information from the plurality of ionization electrodes in response to the variable high voltages pulses. The ionization voltage analyzer produces a gas code identifier in response to the plurality of ionization voltages by defining a code based on which of the ionization voltages exceed an arbitrarily established reference level ionization voltage. A single ionization electrode system can be used to determine a concentration of a particular gas.

Abstract: With a view to enabling errors in the space potential to be automatically corrected by detecting a floating potential in each of a plurality of probes and to remove the errors in measurement based on the corrected space potential to thereby realize the accurate measurement of the space potential, there is provided a triple-probe plasma measuring apparatus, which comprises: a circuit for measuring electron temperature and electron density of a plasma with use of triple probes; a circuit for detecting and holding a floating potential difference; a differential voltage adding circuit; a fixed voltage source; and a change-over switch, the apparatus being capable of determining a difference in the floating potentials at the position of said probes, and superimposing the potential difference determined on the fixed voltage.

Abstract: There is disclosed apparatus for monitoring the concentration levels of halogen gas in a gaseous atmosphere as confined in an enclosure over a relatively extended period of time. Such monitoring apparatus includes a sensor including first and second electrodes disposed to define a space therebetween through which the gaseous atmosphere flows and a voltage source for applying a voltage between the first and second electrodes whereby an ionization current flows to the first electrode. A control mechanism illustratively in the form of a programmed microcontroller monitors the ionization current collected by the first electrode as the output signal of the sensor, to determine an increase therein as would be indicative of a halogen leak. Upon determining an increase of the sensor output signal above a predetermined difference, the control mechanism removes the energization from the halogen sensor whereby the ionization current is terminated and the life of the sensor extended.

Abstract: A surface ionization detector for detecting organic molecules such as illicit drugs and non-organo-nitrate explosives includes a heated surface and a collector electrode. A sample containing trace amounts of the organic molecules in ambient air is directed over the heated surface maintained at a temperature in the range of 500.degree. C. to 800.degree. C., thereby causing the molecules to decompose into fragments. A polarization voltage between 18 V and 24 V is applied to ionize the fragments which are then collected by the collector electrode. An electrometer connected to the collector electrode measures the current and a change in the current indicates the presence of ionized fragments, and thereby indicates the presence of the organic molecules. The temperature of the heated surface and the polarization voltage are optimized for detection of particular organic molecules.

Abstract: A photo-ionization detector utilizes an ultraviolet (UV) lamp for detecting and measuring the concentration of volatile gases flowing between closely spaced parallel electrodes. One of the electrodes is made of mesh to allow photons to pass into the space between the electrodes to ionize the volatile gases between the electrodes. The detector also incorporates an improved ionization chamber. In other embodiments, a plurality of gas discharge lamps, each generating a different photon energy, may be placed adjacent to a plurality of closely spaced electrodes, all electrodes in one ionization chamber, to detect and measure different types of volatile gases that may exist.

Abstract: A pulsed discharge helium photon ionization detector comprises an elongate cylindrical body having an axial flow path. A helium source is connected to deliver helium flowing along this path. In the helium flow path, transversely positioned, facing electrodes are located to form a spark discharged across the helium flow path wherein the spark interacts with the helium to cause photon ionization. Downstream within view of the spark, a counter flow dopant gas injection tube is positioned to deliver dopant at a reduced flow rate. The dopant is swept back along the helium flow path past a set of electrode rings spaced along the flow path. The interaction of the photon ionization with the dopant creates a base current which can be detected by an electrometer across the terminals. A sample injection tube adds an eluted GC column sample or peak which changes the base current so that eluted sample is measured.

Abstract: A spark detection apparatus is set forth and incorporates a closed chamber for receiving a carrier gas flowing therethrough between inlets and outlets, and the carrier gas is exposed to a pair of electrodes forming a spark across the chamber and through the carrier gas. One component of the carrier gas is argon. The sample to be analyzed is injected into the carrier gas. One reaction involves the formation of metastable argon which upon decay serves as a source of ionizing radiation which reacts with sample compounds producing detectable events. These events are used to identify and quantify unknown compounds contained in the sample. The methods and apparatus are especially useful in measuring pollutant compounds in atmospheric samples since the ionizing radiation emitted from the decay of metastable argon is below the ionization potential of the major constituents of air. This greatly enhances the signal-to-noise ratio for detecting impurity compounds when the detection system is used to monitor air quality.

Abstract: A pulsed discharge helium ionization detector set forth and comprises an elongate cylindrical body having an axially flow path. A helium source is connected to deliver helium flowing along this path. At some location in the helium flow path, transversely positioned, facing electrodes are located. When provided with pulses discharged across the helium flow path wherein the discharge is either monopolar or bipolar pulses, the spark interacts with the helium to create photon ionization. Downstream within view of the spark, a counter flow sample injection tube is positioned to deliver samples at a reduced flow rate. The sample is swept back along the helium flow path past a pair of electrode rings spaced along the flow path. The interaction of the photon ionization with the sample creates a current which can be detected by an electrometer across the two terminals.

Abstract: An improved corona discharge detection probe, including a corona discharge gas detector, the detector including electronic circuitry, a cathode electrode, an anode electrode spaced from the cathode electrode, and a mechanism for constraining through the probe the flow of atmospheric air to be sensed. The probe has a tip for initially receiving the flow of atmospheric air to be sensed. An external chamber is included, the external chamber being securable to the tip of the detector probe. An adsorbent material is placed within the external chamber about the detector probe such that ambient atmosphere first flows through the chamber prior to encountering the probe tip. The adsorbent material acts to adsorb water vapor in a controlled manner, such that changes in the water vapor level do not affect the detection probe circuitry and thereby eliminates false alarms.

Abstract: A plasma diagnosing apparatus for performing plasma diagnosis witch probes having a high degree of cleanliness by removing contamination caused by reactive plasma, etc., while quantitatively detecting a degree of the contamination of the probes. The disclosed apparatus avoids the disadvantages of conventional apparatuses, in which the voltage-current characteristics of the probes are deteriorated by growth of the contaminant film formed on the probes, making it difficult to measure the parameters of the plasma conditions.

Abstract: A refrigerant gas leak detector for detecting the location of leaks of refrigerant gas such as halogen has a sensing tip with a pair of electrodes across which a relatively high voltage is generated to cause a corona current to pass through the electrodes. The voltage applied across the electrodes is varied to maintain the corona current through the electrodes at a substantially constant magnitude. The leak detector includes a gas sensing circuit that detects changes in the concentration of refrigerant gas by sensing the voltage applied to the electrodes. The sensitivity of the gas sensing circuit is automatically varied based on the concentration of refrigerant gas present. The leak detector includes a signal generating circuit that causes a number of audible and visual indications to be generated based on the concentration of refrigerant gas sensed as well as other operating conditions.

Abstract: A gas leak detector that operates on the corona principle having a sensing tip with a pair of electrodes across which a high voltage is provided to generate a corona current through the electrodes. The sensing tip includes a first electrode having a conductive housing with a first end having a gas inlet formed therein and a second end and a flow passage formed therein. The flow passage has a first bore provided between the gas inlet and the second end of said conductive housing and a second bore having a diameter smaller than that of the first bore. The second bore is provided between the first bore and the gas inlet of the conductive housing and abuts the first bore to form an edge in the interior of the housing. The flow passage also has a third bore of a diameter smaller than that of the second bore provided between the second bore and the gas inlet. The gas leak detector also includes a second electrode provided in the interior of the conductive housing.

Abstract: A sample is loaded along with a carrier gas into a column. The column discharge is introduced into a chamber downstream of spaced electrodes which create a pulsed DC spark. The spark produces a spectral emission and a metastable carrier gas dispersion that then reacts with molecules of the sample to bring the sample to an excited state. The excess energy surrendered by the sample is characteristic of the species and can be measured by detector electrodes in the chamber.

Abstract: A small, light and portable sensor for detecting and quantifying a harmful high molecular weight substance present in a sample gas in trace amounts is herein disclosed. In the sensor, light and heavy ions are formed by ionizing molecules of the sample gas components in an ionization region. The heavy ions are formed through an ion-molecule reaction. The passage of ions through an ion-passage control region is controlled by directly or indirectly controlling the electric field established between a central electrode and a counter electrode The ions which pass through the control region are collected on a collector electrode. The high molecular weight substance is detected and quantified on the basis of the output from the collector electrode.

Abstract: A method and apparatus are provided for automatically compensating for gain variations, component aging and drift characteristics of an associated circuit when trying to detect a leak. In the preferred embodiment an analog to digital converter will convert an analog signal from a sensor to a digital representation. A microprocessor will read the digital representation and compute the percentage change of the difference in values of the digital representations. Wherever the percentage change is greater than a threshold value, the microprocessor will activate an alarm to inform the user.

Abstract: System and method for detection and measurement of airborne biological aerosol particles in a gaseous sample are described comprising a source of low energy radiation for irradiating the gaseous sample whereby biological particles in the sample are ionized, a detector for detecting ionized biological particles in the sample including a pair of electrically charged conducting plates disposed in parallel confronting relationship to each other with a preselected space therebetween, a source of electrical power operatively connected to the plates for applying a preselected electrical potential thereacross, and electronics for sensing collisions on the plates of ionized biological particles in the sample.

Abstract: A method of correcting first approximation data obtained from a conventional electrozone particle sensing apparatus includes steps for calculating factors for correcting for binary and tertiary coincidences, from the raw data and from physical characteristics of the sensing equipment, to yield an accurate measure of particle distribution within the sample.

Abstract: In a method and a device for measuring the concentration of particles present in a gas, in which a gas stream is guided past a UV light source, the particles are ionized and filtered out and the resulting ionic current is measured, the gas flow required is produced by thermal convection using an internal or external heat source. A suitable internal heat source in this context is, for example, the UV lamp (2) itself, which heats the gas via a radiation absorber (5). The elimination of a mechanical pump reduces the space requirement, power consumption and susceptibility to faults of the measuring arrangement.

Abstract: Molecular ionization detection and analysis including processes and apparatus for photoionizing trace constituents in a carrier gas or effluent from a chromatograph in a manner that substantially increases the effective sensitivity. The invention uses a pulsed gas valve to introduce a high density gas sample into a vacuum system where the trace constituents in the jet are photoionized by an intense vacuum ultraviolet [VUV] pulse from a flashlamp. The ions are extracted from the beam under free molecular flow conditions. This source may be used with the ion energy analyzer to eliminate any interference due to background gases in the vacuum system and to provide mass analysis of the eluting trace constituents.