Ion spectrum measurement process and transit-time ion spectrometer
 Ion spectrum measurement process and transit-time ion spectrometer / 2266587Charge and mass composition is measured by accelerating ions in accelerating gap formed in vacuum chamber between input end of drift tube and plasma when negative-polarity voltage pulse of length shorter than transit time in drift tube of accelerated ions of plasma being analyzed is applied to drift tube at maximal Z/Mi ratio, where Z is ion charge in plasma; Mi is ion mass. Voltage pulse is supplied from negative-polarity accelerating-voltage pulse source whose high-voltage lead is electrically connected to drift tube and other lead, to vacuum-chamber ground. When in transit, accelerated ions are divided within drift tube into mass, charge, and energy clots and separated clots are recorded by detector. |
 Analyzer of energies of charged particles / 2294579Analyzer of charged particles energy contains sample (emitting charged particles), external electrode and internal electrode with two circular slits and detecting system. Axial and radial gradients of energy analyzer field potential are synchronized along movement route of charged particles by setting appropriate configuration of equipotential surfaces of analyzer electrodes. |
 Transit-time mass spectrometer / 2295797Proposed mass spectrometer that can be used for solving problems in organic chemistry, biochemistry, immunology, medicine, biotechnology, environment control, for evaluating composition and properties of materials in industry and scientific research has pulsed ion source, drift space with two flat braking-field wire-net capacitors and detector installed in tandem at its end is provided with second drift space formed by common electrodes of flat wire-net capacitors spaced along device axis; potential of second drift space is braking one with respect to first drift space. |
 Transit-time method for metering charge and mass composition of plasma ions / 2314594Proposed method involves immersion of drift tube into plasma followed by acceleration of ions by applying negative-polarity voltage pulse across drift tube, pulse length being shorter than its transit time within drift tube carrying analyzed plasma accelerated ions at highest Z/Mi ratio, where Z is degree of ion charge in plasma; Mi is ion mass; this is followed by separating ions with respect to their mass, charge, and energy as they are conveyed through equipotential space of drift tube, as well as measurement of ion current pulse at drift tube outlet; then second measurement similar to first one is made but for different length of negative-polarity voltage pulse supplied to drift tube; charge and mass composition of plasma ions is evaluated by subtracting results of measuring ion current pulses at outlet of drift tube obtained at different lengths of negative-polarity voltage pulses. |
 Dust impact mass spectrometer / 2326465Invention relates to the instrument engineering, automation means, and control systems, namely, to the space research area. The dust impact mass spectrometer contains a hemispheric target with one opening in the middle of its surface, which increases the probability of target impact with a micrometeorite at the same dimensions of the mass spectrometer. The accelerating gap is a limited by a hemispheric target and a hemispheric grid, located concentrically, which provides equal ion trajectory lengths, thus eliminating the measurement result dependence on the impact location and increases the measurement result reliability. The parabolic reflector focuses ions into a parallel beam directed exactly to the hemispheric target opening. |
 Mass selective device and analysis method for drift time of ions / 2327245Invention pertains to the field of dynamic mass analysis of charged particles in alternating HF fields. The mass-selective method of separating ions is based on the use of an analyser, consisting of two flat parallel electrodes with linear-discrete and anti-phased HF potential distributions on the Y axis and a flat earthed electrode, and a limiting electrode with values y≥0. The discrete electrodes are made in the form of capacitor or inductive linear HF voltage dividers. Applied to the electrodes are two anti-phased HF voltages with constant amplitude Um and frequency, ω for which a linear alternating electrical field is formed in the analyser on the X and Y axis. Ions are put into the analyser through the opening in the flat earthed electrode with initial coordinates xn>0, уn=0 and initial velocities vu, inversely proportional to the masses, m of the analysed ions. Ions on the X and Y axes have almost harmonic oscillations with the same amplitude уm and period T, proportional to mass m. During the analysis period the x coordinate of the ions changes to the opposite x(tA)=-xn, while the y coordinate becomes equal to y(tA)=0. The sorted out ions in accordance of their mass m, successively pass into the analyser and reach the registration system. |
 Ion mobility spectrometer / 2328791Ion mobility spectrometer contains the neoformation chamber with installed ion source, drift chamber with the ion collector and aperture mesh, ejecting electrode and the mesh gate which form the ejection area, holes for supplying the mixture of the analised substance with carrier gas, and drifting gas and for outputting the drift gas and the mixture of the analised substance with carrier gas. The chamber of ion-formation with the ion source is placed out of the ejection area and connected with it via adapter with the canal for ion transportation; at that, the ion-formation chamber has the potential of the mesh gate. The adaptor canal has the conical shape, at the ion-formation chamber, which becomes slit-like at the ejection area. The planes of the slit-like canal are parallel to the mesh gate. The length of the slit-like canal is selected so as to guide the ion and carrier gas flow along the ejecting electrode and the mesh gate. The length of the slit-like canal is more or equal to the canal's width, and the canal's width is equal to or less than the distance between the mesh gate and the ejecting electrode. |
 Method and device for identification of organic compounds / 2329563Invention is related to the field of gas analysis, in particular of vapours of explosive, narcotic and poisoning substances. Method of organic compounds identification consists in measurement of volt-ampere characteristics with application of surface-ionisation source of ions, in which measurement of volt-ampere dependence is carried out in interval of voltages "thermal emitter of ions - electrode for ion current control" from U1 to U4, volt-ampere dependence section is separated from U2 to U3>U1, in which value of current of organic compounds ions quadratically depends on value of voltage "thermal emitter of ions - electrode for ion current control", at that U1 and U4 are selected based on conditions U4>U3, U1<U2, at that volt-ampere dependence is used for determination of value of organic compounds ions drift mobility and/or for determination of energy activation value of organic compounds molecules ionisation on thermal emitter surface, at that for determination of organic compounds ions drift mobility value section is used from U2 to U3 of volt-ampere characteristic, and for determination of energy activation value of organic compounds molecules ionisation section is used from U3 to U4 of volt-ampere characteristic. Device is suggested for identification of organic compounds, which contains two structurally identical surface-ionisation sources of organic compounds ions, at that inlet openings of channels of nozzles for intake of analysed air flows of the first and second sources of ions are combined into common channel of common nozzle for intake of analysed air flow. |
 Mass spectrometer for macromolecule analysis / 2332748Mass spectrometer contains holder with analysed substance, ionisator and supplier of macromolecules to mass analyser, and detector. Mass analyser is connected to holder with analysed substance, and detector is based on matrix of micromechanical cantilevers providing determination of interaction time point and point where accelerated macromolecule contacts with petal surface of micromechanical cantilever, providing macromolecule pulse transfer to micromechanical cantilever petal, and following deviation of petal by the distance determined by weight and energy of macromolecule. Thus detector is implemented within consistently optically connected emitting sources, collimating optics, micromechanical cantilever matrix, projecting optics and photodetector, while micromechanical cantilever matrix thereof is designed as detector substrate where micromechanical cantilevers are mounted, thus micromechanical cantilever is designed as part of leg, arm, reflecting layer. Micromechanical cantilever matrix is multielement. |
 Mass-sensitive selective concentrator for ion mobility spectroscopy (ims) / 2379678Invention relates to analytical instruments, particularly, to devices intended for preliminary concentration of analyzed sample and combined with analytical instrument that can be used to produce fast-operation analyzers of poisonous or explosive substance concentration in air. Proposed concentrator comprises analyzed sample fast-desorption absorbing element and acoustic transducer with its output signal depending upon mass of absorbed sample. Acoustic transducer represents a piezoelectric plate-sound conductor with two built-in interdigital electromechanical transducers (IDT), designed to excite and receive surface acoustic waves (SAW). While absorbing element represents a film made from molecular imprinting polymer applied onto said plate-sound receiver surface and consisting of two sections, i.e. small-area detecting section located on SAW propagation line, and larger-area concentrating section located outside acoustic line. Said concentrating section can comprise two additional sections to double as SAW-absorbing coatings. To this end, said additional sections are arranged on plate-sound receiver surface, on SAW propagation line outside the space between IDT. |
FIELD: charged particle spectrometry; measuring charge and mass composition.
SUBSTANCE: charge and mass composition is measured by accelerating ions in accelerating gap formed in vacuum chamber between input end of drift tube and plasma when negative-polarity voltage pulse of length shorter than transit time in drift tube of accelerated ions of plasma being analyzed is applied to drift tube at maximal Z/Mi ratio, where Z is ion charge in plasma; Mi is ion mass. Voltage pulse is supplied from negative-polarity accelerating-voltage pulse source whose high-voltage lead is electrically connected to drift tube and other lead, to vacuum-chamber ground. When in transit, accelerated ions are divided within drift tube into mass, charge, and energy clots and separated clots are recorded by detector.
EFFECT: facilitated procedure.
6 cl, 1 dwg
The invention relates to the field of spectrometry of charged particles and can be used for measuring the charge and mass composition of plasma.
Known time-of-flight method for measuring the spectrum of ions [1] by their extraction from plasma, acceleration and beam shaping, short-pulse effects on the ion beam radial electric field within 100 NS and subsequent transport of the ion beam in the drift tube and it is registered by the detector.
The separation of ions according to mass, charge and energy is implemented in the specified method is not for the entire beam, the duration of which may substantially exceed 100 NS, but only for the portion of the beam, which has passed the system of rings during the presence on it of the radial electric field. Radial electric field that focuses ions of the beam on the detector small size. The detector is blocked from a direct hit unfocused beam. Thus, ions of the beam passing through the radial deviation in subsequent during transport in the drift chamber are separated by the time of their arrival at the detector, depending on their mass and energy.
Time-of-flight spectrometer that implements the above method [1], contains a source of accelerated ions, a system of concentric rings located perpendicular to the axis of movement of the ion beam, and the ion collector. On the concentration of the automatic spaced rings pulsed voltage bias so what ions, passing in the gap between the rings within the applicable impulse voltage gain momentum energy radial direction and in the subsequent focus in the area of the collector. In the absence of a bias voltage, the ion beam passes the system rings without changing the trajectories of the ions.
Thus, the total duration of the ion beam T is allocated a pulse of ions duration τ. On a span basis between the rings and the collector ions of different seragnoli and mass separated and arrive at the collector at different times.
The disadvantage of this method and spectrometer is the need to have pre-formed stream of accelerated ions. This spectrometer cannot be used to analyze the charge and mass composition of plasma.
There is also known a method of measuring the spectrum of ions [2] by extraction from plasma and ion acceleration in the accelerating gap, the subsequent injection and transport of the ion beam in the drift tube to separate it into separate clots in accordance with the charge, mass and energy composition of ions and detection of separated clusters. The acceleration of ions is performed by application of a pulse of positive polarity to the input node of the plasma flow in the spectrometer and grounded drift tube. In the accelerating gap is formed of outlawed plasma and the input end of the drift tube. The method chosen for the prototype.
The disadvantage of this method lies in the technical difficulties of its implementation. The duration of the ion beam must be small, thereby providing full accelerating voltage of the separation of ions by mass and seragnoli in the drift tube of a reasonable length (e.g., several meters). Thus, the scope of application of the method is limited only by the accelerators and ion sources nanosecond duration. The method is not applicable for the analysis of the spectrum of plasma.
Also known time-of-flight spectrometer [2]that implements this method consists of sequentially disposed in the vacuum chamber of the plasma source, the accelerating period, the drift tube and ion collector. The output aperture of the plasma source is a node of the input plasma flow in the spectrometer. Accelerating gap is formed between the output aperture of the plasma source and the entrance of the drift tube to the outlet aperture of the plasma source connected to the high voltage output of a pulse source accelerating voltage of positive polarity. The drift tube is connected to the grounded terminal of the voltage source. When applying a short duration pulse accelerating voltage of positive polarity at the output aperture of the plasma source from it are extracted and accelerated ions. Formed Jonny the beam, during its movement in the drift tube, is divided into separate bundles in accordance with the charge, mass and energy composition of the ions. By the time of arrival at the collector of the ions is determined by the mass and charge composition of the beam. The proportion of each type of ions in the total beam is determined by the ratio of the areas of the peaks of the waveform of the current collector.
The disadvantage of this spectrometer is that the extraction of ions takes place directly from the source which is under the accelerating potential. This spectrometer is not possible to measure the charge-mass composition of the ions in the free plasma or directionally moving the plasma flow at any distance from the source.
Object of the invention is to provide a method for measuring a spectrum of ions and time-of-flight spectrometer ions with more functionality.
The technical result achieved by the invention, is the ability to measure the charge-mass ion composition of the plasma produced by any plasma source and at any distance from him.
The problem is solved in that a method of measuring the spectrum of the ions, as a prototype, provides for the acceleration of ions in the plasma transport in the drift tube for separation by mass, charge and energy with the subsequent registration of separated clusters. In contrast to proto the IPA in the proposed method, analyzed the plasma is in direct contact with the entrance of the drift tube, and acceleration of ions is performed by the feed pipe drift voltage pulse of negative polarity. The pulse duration is chosen less time-of-flight in the drift tube of accelerated ions of the analyzed plasma with the highest ratio Z/Mi, where Z is the charge of the ions in the plasma, Mi is the ion mass.
Accelerating gap is not specified the structural elements of the device, as is the case in the prototype, and is formed between the input end of the drift tube and the plasma when applying a negative accelerating potential on the drift tube. Here in plasma is formed a layer of charge separation, and accelerated in this layer at the entrance of the drift tube the ions immediately fall into the drift tube. During the drift in the pipe ions are spatially separated in accordance with their velocity Vi, which is determined from the expression
where e is the electron charge, U is the accelerating voltage.
Choosing the pulse duration of the accelerating voltage less time-of-flight-in-pipe drift of ions with the highest ratio Z/Miensure the arrival at the detector, even the fastest ions after the expiration of the accelerating voltage. Thus, none of the varieties analyzed ions misses retarding electric field existing in the duration of the voltage pulse between the exit end of the pipe the drift and the detector. By the time of arrival of ions at the detector, and the amplitude of the signal from the detector to determine the charge and mass composition of plasma ions.
In the device the problem is solved in that time-of-flight spectrometer ions as the prototype contains the drift tube and the detector successively arranged in the vacuum chamber, and a pulsed accelerating voltage source. Unlike the prototype pulse source accelerating voltage is made negative polarity and high voltage output electrically connected to the drift tube, and the other output is connected to the grounded casing of the vacuum chamber. The pulse source accelerating voltage is performed with a pulse duration of τythat satisfies the relation
where letc.the length of the pipe drift, Mi/Z-greatest ratio of the mass of the ions to seragnoli for ions of the analyzed plasma; U is the accelerating voltage.
To increase the length of the free drift of the ions with the fixed length of the drift tube entrance and exit of the drift tube, it is advisable to close the electrodes is transparent to ions, such as nets.
To improve transportation conditions of accelerated ions in the drift tube electrode is located at the inlet end of the tube drift, perform convex outward from the pipe drift. It provides the t beam focusing and reduces the ingress of the analyzed ions on the walls of the pipe.
The length of the accelerating gap, which is formed near the electrode at the entrance of the drift tube, depends on the properties of plasma, such as plasma density, a variety of ions, having directed along the pipe axis of the drift velocity of the plasma, the plasma temperature and the amplitude and duration of the accelerating voltage, and may vary from fractions of millimeters to tens of centimeters.
Given that the energy of ions at the entrance to the drift tube dynamically changes with increasing accelerating gap, to improve resolution of the spectrometer when the alleged gaps greater than 1 mm in front of the entrance electrode tube drift impose additional grounded electrode. The presence of this electrode also reduces the loss of accelerating voltage on the resistive current in the plasma.
To increase the efficiency of transport of ions in the pipe when accelerating gap, fixed two electrodes, the input electrode of tube drift, and more grounded electrode is performed convex outward from the pipe drift.
Plasma, the charge and mass which is required to measure a given spectrometer, ions can be created by any method including vacuum-arc discharge, RF and microwave discharges, various gas plasma sources, the laser radiation.
The invention is illustrated in the drawing, which presents the Jena schematic diagram of the TOF spectrometer ions.
Time-of-flight spectrometer is installed in the vacuum chamber 1 and consists of a drift tube 2, made of metal, the input and the output of which is closed by the electrodes 3 and 4 are transparent to ions, such as metal mesh, electrically connected with the drift tube 2. Before entering the drift tube 2 near the electrode 3 is grounded electrode 5, transparent to ions, such as metal mesh. The electrode 3, installed at the entrance of the drift tube 2 and the grounded electrode 5 form the accelerating gap and can take the form of a plane or shape, convex outwards from the pipe drift 2. The convex shape allows focusing of the generated ion beam. In another embodiment, in the absence of the grounded electrode 5, the accelerating gap is formed by the electrode 3, installed at the inlet of the drift tube 2 and the plasma 6, with an electrical contact with the grounded casing of the vacuum chamber 1. Opposite electrode 4 located at the exit of the drift tube 2, with the vacuum gap is installed detector 7 charged particles. The detector 7 is electrically connected with a measuring current of charged particles. Pulsed accelerating voltage source of negative polarity, which is the voltage impulse generator 8 connected to the high voltage output to the pipe drift 2. The second output of the generator is grounded to the camera 1 and the electronic is rejeski connected to the grounded electrode 5.
The device operates as follows. Consider the operation of the device on the example of forming the metal plasma vacuum arc evaporator operating in a continuous mode. Metal plasma comes from a source in the vacuum chamber 1, filling its volume. Analyzed the plasma moves along the axis of the drift tube and is in contact with the entrance of the drift tube. From the high-voltage impulse generator 8 negative polarity serves pulse voltage amplitude U and the duration τ between the drift tube 2 and the vacuum chamber 1.
When the bias potential of the drift tube 2 between the plasma 6 and the electrode 3 and between the electrode 4 mounted on the outlet of the drift tube and the detector 7, separated from the drift tube 2 by a vacuum gap, there is a potential difference. The appearance of a potential difference between the electrode 3 and the plasma 6 leads to charge separation in the plasma and accelerate ions from the plasma to the electrode 3, and electrons in the opposite direction. Accelerated ions pass through the electrode 3 and are in an equipotential space of the drift tube 2. In the drift tube 2 the charge of the ion beam is neutralized by the electrons present in the pipe plasma. Ions of the beam drift in the drift tube 2 with velocities determined by the ion energy and mass.
At the same time with the appearance of bias potential on the drift tube 2 between e what STRADOM 4 and the detector 7 particles also occurs a potential difference. In the gap between the electrode 4 and the detector 7 is accelerated ions in the direction of the drift tube 2 and the acceleration of electrons toward the detector 7 of charged particles. Given that the velocity of the electrons on the orders of magnitudes more speed even hydrogen ions, the electrons reach the collector in a very short time (a few nanoseconds). In this regard, the beginning of the signal electron current from the collector serves as a temporary reference for the determination of mass and charge composition of the ions in the spectrometer of this type.
The pulse duration of the high voltage bias from a high voltage pulsed generator 8 choose one of the following conditions.
The minimum pulse width of the offset is determined by the processes of formation of the accelerating gap between the electrode 3 and 6 or plasma between the electrodes 3 and 5. First, when applying a potential bias from the high voltage pulsed generator 8 to the drift tube 2, the accelerating gap is formed due to the displacement of the plasma electrons. This process shall not exceed a few nanoseconds. The concentration of ions formed around the gap will be the same and correspond to the initial concentration of the plasma. When ions located at different distances from the electrode 3, installed at the entrance of the drift tube 2, is accelerated in the gap will receive a different energy. At least accelerated the I ions will be redistribution of ions in the accelerating gap. Stabilization of the emission boundaries will occur either when the width of the accelerating period will be equal to the value defined by the second law of three, or if the emission boundary of the plasma will come to the electrode 5. Depending on the plasma parameters and the magnitude of the accelerating voltage stabilization time of emission of the border can be from several tens to several hundreds of nanoseconds. The pulse width of the voltage impulse generator 8, it is advisable to choose such that it exceeded the stabilization time of emission of the border τc. An essential condition for the duration of the pulse accelerating voltage is drift all accelerated ions analyzed plasma, including the fastest having the largest ratio Z/Mi, for the duration of the accelerating voltage, inside the drift tube. This means that the accelerated ions will not get in their inhibitory electric field between the electrode 4 mounted on the outlet of the drift tube 2 and the detector 7. The maximum energy E of the ions within the drift tube, is determined by their charge and accelerating voltage
E=ZeU
The largest drift velocity is the ion with the highest ratio Z/Mi. The time drift of these ions τothersis determined by the expression
Thus, the duration of the pulse is Lisa accelerating voltage τ ychoose from the condition
τy<τothers.
Ions with a smaller ratio Z/Mi will move slower and will detector, when there clearly will be no electric field in the gap between the electrode 4 and the detector 7.
The ions on the detector 7 come at different times, which is reflected, for example, an oscilloscope. In the future, the waveform determine the mass and charge of the ion composition and the percentage of individual component ions in the plasma.
A sample implementation of time-of-flight spectrometer. Vacuum arc evaporator operates with a cathode made of titanium. Plasma concentrations of 6 near electrode 3 is (1·109-1010) ion/cm3. The drift tube 2 with a diameter of 100 mm has a length of 600 mm titanium Ions with a charge of 1, 2, 3, and 4 well-separated at pulse duration of 500 NS and accelerating negative potential with high-voltage impulse generator 8 amplitude 1000 C.
Sources of information
1. I.G.Brown, J.E.Galvin, R.A.MacGill, R.T.Wright. Improved time-of-flight ion charge state diagnostic./Rev. Sci. Instmm. 58(9), September, 1987, p.1589-1591.
2. S.P.Gorbunov, V.P.Krasov, I.A.Krinberg, V.L.Papemy. Source of metal ions with a variable velocity./6thInternational Conference on Modification of Materials with Particle Beams and Plasma Flows. 23-28 September 2002, Tomsk, Russia, page 67-70.
1. Method of measurement of plasma ions by accelerating the ions, their transport in the drift tube for separation by mass, charge and energy is AI and the subsequent registration of the divided clumps characterized in that the analyzed plasma is in direct contact with the entrance of the drift tube, the acceleration of ions in the plasma is produced by applying to the drift tube voltage pulse of negative polarity, duration, less time-of-flight in the drift tube of accelerated ions of the analyzed plasma with the highest ratio Z/Miwhere Z is the charge of the ions in the plasma, Mi- mass ions.
2. Time-of-flight spectrometer ion plasma containing a vacuum chamber, in which are positioned successively pipe drift and the ion detector, and pulse accelerating voltage source, characterized in that the detected plasma is in contact with the entrance of the drift tube, the pulse source accelerating voltage is performed with a negative polarity and the high-voltage terminal electrically connected to the drift tube, the other output is connected with the grounded casing of the vacuum chamber.
3. Time-of-flight spectrometer according to claim 2, characterized in that the input and output ends of the drift tube installed electrodes, transparent to ions and electrically connected with the pipe drift.
4. Time-of-flight spectrometer according to claim 3, characterized in that the electrode is located at the inlet end of the drift tube, is made convex outward from the pipe drift.
5. Time-of-flight spectrometer according to any one of claim 2 to 4, characterized in that is contains more grounded electrode, located in front of the entrance end of the tube drift.
6. Time-of-flight spectrometer according to claim 5, wherein the grounded electrode is made convex outward from the pipe drift.