EP0122403A1 - Plasma excitation system - Google Patents

Plasma excitation system Download PDF

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Publication number
EP0122403A1
EP0122403A1 EP84101792A EP84101792A EP0122403A1 EP 0122403 A1 EP0122403 A1 EP 0122403A1 EP 84101792 A EP84101792 A EP 84101792A EP 84101792 A EP84101792 A EP 84101792A EP 0122403 A1 EP0122403 A1 EP 0122403A1
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EP
European Patent Office
Prior art keywords
plasma
power
radio frequency
work coil
generator
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP84101792A
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German (de)
English (en)
French (fr)
Inventor
John Armand Bernier
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Allied Corp
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Allied Corp
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Filing date
Publication date
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Publication of EP0122403A1 publication Critical patent/EP0122403A1/en
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00—Generating plasma; Handling plasma
    • H05H1/24—Generating plasma
    • H05H1/46—Generating plasma using applied electromagnetic fields, e.g. high frequency or microwave energy

Definitions

  • the invention relates to radio-frequency (rf) power generators. More particularly, it relates to rf generators for generating and exciting an inductively coupled plasma (ICP) employed in atomic emission spectrometry.
  • ICP inductively coupled plasma
  • ICP Inductively coupled plasmas
  • a rf generator ordinarily provides power to combined tuning- work coil.
  • This coil operates both as the inductor coil in the output tuning (tank) circuit of the generator and as the plasma producing work coil.
  • the plasma is typically annular in shape, providing a tunnel region into which a sample is introduced for excitation.
  • the radiated power from the generator may be closely regulated and the AC frequency of operation kept within a specific allowed bandwidth to prevent rf interference with other devices, such as nearby communications equipment.
  • the AC frequency has been substantially fixed by use of a crystal controlled oscillator.
  • Generators with crystal controlled rf oscillators typically require additional amplifier stages to develop the output power needed to produce and sustain an ICP, and often employ special rf transmission cables, rf connectors and associated impedance matching circuitry.
  • special, complex tuning adjustment circuits have been required to compensate for resonant frequency shifts that occur in the output tuning circuits during periods of plasma ignition and plasma excitation of an analytic sample.
  • the rf power output tuning circuit becomes mismatched from the fixed oscillator frequency. This changes the power delivered into the tuning-work coil and causes fluctuations in the plasma intensity. The plasma may even extinguish.
  • complex circuits have been employed to closely regulate power output, voltage phase relations and resonant frequencies of the output tuning circuits to ensure adequate power into the plasma.
  • Radio-frequency generators which employ a free-running oscillator have generally been preferred because they are simpler and more economical than generators with fixed frequency oscillators.
  • ordinary exciter systems using such generators experience very large frequency shifts sweeping over hundreds of kilohertz, particularly during plasma ignition.
  • conventional generators with free-running oscillators exceed allowable operational bandwidths and have required bulky and costly rf shielding to prevent disruptive rf interference with other equipment.
  • the invention provides an economical and efficient radio-frequency (rf) excitor apparatus and method for producing an inductively coupled plasma to heat an analytic sample.
  • the excitor apparatus includes a radio-frequency generator means for producing electrical power of selected radio frequency.
  • the generator means has power output tuning means comprised of at least one output tuning inductor for determining the generator radio frequency.
  • a separated plasma load circuit is coupled to the generator means and is comprised of a work coil and a series connected, impedance matching capacitor.
  • the work coil is adapted to produce an inductively coupled plasma and the capacitor is adapted to substantially balance and counteract the combined inductive reactances of the work coil and plasma.
  • Control means for controlling the power input into the plasma load circuit stabilize the plasma.
  • an excitation method for producing an inductively coupled plasma to heat an analytic sample Electrical power of selected radio frequency is generated with an rf generator means having a power output tuning means.
  • the power from the generator means is directed to a plasma load circuit having a separate work coil adapted to produce the inductively coupled plasma, and the power input to the separated work coil is controlled with control means operably coupled between the plasma load circuit and the generator means.
  • the exciter apparatus of the invention is versatile and suitable for use in small, office-type laboratories where three-phase power is generally unavailable.
  • the apparatus requires only single-phase power and includes a free-running oscillator. Since the oscillator is free running, it automatically compensates for changing load impedance by shifting its frequency of oscillation to sustain maximum power transfer into the plasma.
  • the plasma load circuit advantageously separates and substantially isolates the plasma producing work coil from the output tuning circuit of the rf generator, and preferably is directly coupled to the rf generator to minimize coupling losses. Since the work coil is separated and substantially isolated from the rf generator tuning circuit, changes in the work coil impedance which occur during plasma ignition and the introduction of a sample into the plasma are for the most part not reflected back into the generator rf tuning circuit. As a result, the rf generator and exciter apparatus exhibit only a small frequency shift of less than about 100 KHZ even under the widely changing plasma load conditions of plasma ignition. In addition, the isolation of the work coil advantageously permits use of a longer work coil having a greater number of turns to produce a longer and broader plasma.
  • the broader plasma in turn, produces a more intense excitation of the sample which allows detection of smaller amounts of constituent elements and renders a more precise analysis.
  • full power is delivered to the work coil even when the gas present at the coil is un-ionized.
  • the complexity of plasma ignition is greatly reduced.
  • Rf power into the plasma is stable throughout the ignition sequence, and the plasma can be initiated and expanded without utilizing complex controls to regulate power input to the work coil and plasma.
  • the invention provides a more compact, efficient and economical exciter apparatus.
  • the exciter apparatus more precisely analyzes a selected sample and more efficiently delivers maximum power to ignite and sustain an ICP load. Power into the ICP is stabilized without complex power supplies, without complicated power regulation and without causing excessive shifts in the rf power frequency.
  • FIG. 1 illustrates a schematic representation of an apparatus for analyzing the constituent elements of a sample of selected material.
  • the apparatus is comprised of an exciter 1 and an analyzer means 8.
  • Exciter 1 is comprised of rf generator 2, power supply 3 and plasma torch 7.
  • Plasma torch 7 includes a torch tube 6, work coil 19 and a gas supply 31.
  • Analyzer means 8 is comprised of spectrometer 9, computer 11 and readout means 13.
  • rf generator 2 To analyze a sample, rf generator 2 generates rf power and provides it to torch 7. Work coil 19 is wound around torch tube 6 and adapted to produce an inductively coupled plasma 27 from a suitable gas, such as argon, supplied from gas source 31.
  • sampler means 5 injects an analytic sample 25 (analyte) of selected material through conduit 23 into plasma 27. The sample is heated and excited to radiate atomic emission spectra 33, which are characteristic of the constituent elements in the material.
  • spectra 33 is detected by spectrometer 9 to produce a spectrometer output signal.
  • Computer 11 processes the spectrometer output signal and provides a readout analysis of the constituent elements and quantities thereof.
  • suitable readout means would include electronic displays and hard copy printouts.
  • FIG. 2 shows a more detailed schematic block diagram of rf generator 2.
  • the rf generator is comprised of rf amplifier 29, tuning means 15 and coupling means, such as capacitor 17.
  • Power supply 3 provides power to rf amplifier 29 which is connected to power output tuning means 15.
  • Tuning means 15 is comprised of at least one tuning inductor 21 and a tuning capacitor 35. Preferably the inductor and capacitor are connected in parallel to form an electronic, parallel resonant tank circuit.
  • Coupling capacitor 17 is operably connected in series with separated work coil 19 and then operably connected to tuning inductor 21.
  • rf amplifier 29 and tuning means 15 in combination form an rf oscillator which provides the required rf power into tuning inductor 21.
  • the resonant tank circuit formed by tuning inductor 21 and capacitor 35 controls the frequency of oscillation in accordance with well-known electronic principles.
  • the component values are selected to provide oscillation at 27.12 MHz, the U.S. Industrial Band.
  • Coupling capacitor 17 is preferably a vacuum, variable capacitor.
  • Capacitor 17 couples rf power into work coil 19 and provides an impedance matching means to maximize the power delivered into the coil and into plasma 27.
  • the reactance of capacitor 17 is adjusted to balance and substantially counteract the combined reactances of coil 19 and plasma 27 to maximize the power delivered there into.
  • tuning inductor 21 and work coil 19 are constructed from tubular material, for example tubular copper, to allow passage therethrough of a suitable fluid coolant, such as water.
  • Gas source 31 provides a suitable gas, such as argon or nitrogen into torch 7.
  • a suitable gas such as argon or nitrogen into torch 7.
  • the high frequency magnetic field induced in coil 19 by rf generator 2 produces a magnetic field which ionizes the gas to produce a plasma which can reach temperatures of about 10,000°K.
  • the frequency of power and the gas flow are regulated to produce a stable, annular shaped plasma 27.
  • Annular plasma 27 advantageously forms a stable "tunnel" region into which analyte can be efficiently and reliably introduced for excitation.
  • Conventional excitor apparatus typically include a tuning inductor integral with the work coil as schematically shown in FIG. 3, generally at 38.
  • L the inductance of coil 37
  • C the capacitance of capacitor 35.
  • L' the effective equivalent inductance provided by the combination of coil 37 and the equivalent plasma circuit 28.
  • Rf generators such as those employing crystal controlled oscillators require complicated power regulators to assure delivery of adequate power to the work coil to initiate and sustain plasma 27.
  • Rf generators with free running oscillators can shift their frequency of oscillation to insure delivery of adequate power to work coil 19, but the frequency shifts can often exceed the allowable operational band widths and necessitate the use of expensive and bulky rf shielding.
  • the invention advantageously separates tuning inductor 21 from work coil 19 with an impedance matching capacitor 17.
  • the reactance of capacitor 17 is adjusted to substantially balance and counteract the combined inductive reactances of work coil 19 and plasma 27.
  • the plasma load appears as a substantially resistive load to the output of rf generator 2 over a large band width of frequencies.
  • the configuration minimizes changes in effective inductance seen by tuning means 15 during start-up and during the injection of sample into plasma 27.
  • the configuration minimizes the shift in the tuned frequency of tuning means 15 and the output of rf generator 2.
  • the frequency shift can be reduced by limiting the number of turns in work coil 19 to about 1 or 2 turns.
  • the fewer turns in coil 19 provides a smaller inductance and thus a smaller effective inductance change during changing plasma load conditions. As a result, less frequency shift occurs in the tuned output circuitry of the rf generator.
  • the invention allows a much greater change in the effective inductance of work coil 19 while minimizing the effect on the tuned output of the rf generator.
  • a work coil with greater number of turns can be employed without adversely affecting the rf generator output frequency.
  • the greater number of turns provides a larger and broader plasma.
  • the larger plasma in turn provides a larger heating zone which better excites an analytic sample.
  • a more intense emissions spectra is then available to the spectrometric detector.
  • the present embodiment of the invention employs a three and one-half turn work coil.
  • FIG. 4 shows a preferred free running oscillator circuit employed in the excitor apparatus of the invention.
  • High voltage enters the circuit at A2JI, is filtered by choke Ll and capacitors C3 and C5, and applied to the plates of Vl and V2 through quarter wave choke L2.
  • Electron tubes Vl and V2 are parallel connected to provide the required power output and to reduce the effective plate impedance. It is readily apparent that additional tubes could be employed to raise the power output or that the multiple tubes could be reduced to a single large tube.
  • Networks L3 and L4 are heavily damped inductances called parasitic suppressors that prevent intertube resonances in the parallel tube configuration.
  • Transformer Tl provides filament power for both tubes.
  • Capacitors C6 and C16 bypass any rf energy generated at the two filaments to ground.
  • the voltage at the plates of the tubes is coupled to a parallel resonant circuit comprised of a triple capacitor Cll, C12, C13 and an inductor L5 by way of coupling capacitor C7.
  • This resonant circuit is tuned to oscillate at a nominal 27.12 MHz.
  • a 180° out of phase voltage to power the tube grids is derived from the lower section of L21.
  • This voltage is applied in parallel to the grids of the oscillator tubes Vl and V2 by way of the grid leak capacitor combinations Cl, C2 and C9, C10.
  • Negative grid bias for tube Vl is generated by grid leak resistor Rl.
  • Negative grid bias for tube V2 is generated by grid leak resistor R3.
  • Resistors R2 and R4 provide a measurement of the individual tube grid currents monitored in the power supply unit.
  • Power is coupled to the plasma load coil from the center section of inductor L21.
  • Tuning capacitor C17 compensates for the inductance formed by the plasma work coil L19 and the plasma itself.
  • Air cooling is provided by a fan Bl, and both inductor L21 and the plasma work coil L19 are water cooled.
  • the shown circuit forms a Hartley-type oscillator, and with proper selection of the reactances of capacitor 35 and inductor 21, the circuit will oscillate at the preferred nominal frequency of 27.12 MHz.
  • a vacuum tube is able to act as an oscillator because of its ability to amplify. Since the power required by the input of an amplifier tube is much less than the amplified output, it is possible to make the amplifier supply its own input. When this is done, oscillations will be generated and the tube acts as a power converter that changes the direct current power supplied to the plate circuit into alternating current energy in the amplifier output.
  • the voltage fed back from the output and applied to the grid of the tube must be 180° out of phase with the voltage existing across the load impedance of the plate circuit of the amplifier, and must have a magnitude sufficient to produce the output power necessary to develop the required input voltage. In the Hartley circuit this is accomplished by applying to the grid a portion of the voltage developed in the resonant circuit.
  • This grid leak bias makes the oscillator self-starting and insures stable operation under the desired voltage and current relations.
  • the use of a grid leak makes the oscillator self-starting because when the plate voltage is first supplied, the grid bias is zero, making the plate current, and hence the amplification, large.
  • the transient voltage generated will start building up oscillations at the frequency of the resonant circuit. These oscillations cause the grid to draw current which biases the grid negative as a result of the grid leak resistance. This reduces the DC plate current until ultimately equilibrium is established at an amplitude such that the plate current is reduced to the point where the amplification is exactly 1.
  • the grid leak provides a stability because any decrease in the amplitude of oscillation also reduces the bias developed by the grid leak arrangement, thereby increasing the grid drive and increasing the amplitude of oscillation.
  • the rf coil containing the plasma may be regarded as the primary coil of a kind of a transformer.
  • a plasma which also has inductance, acts as the secondary winding 85 consisting of a single turn.
  • the coupling between the primary and secondary windings increases with the diameter of the plasma. Fluctuations in the energy content of the plasma affect the diameter of the plasma through temperature changes; the situation resembles that of a gas at constant pressure and changing temperature.
  • FIG. 6 illustrates how the variation of the coupling factor can give stabilization.
  • L t and R represent the effective impedance constituted by the plasma work coil and the plasma.
  • the load appears to be entirely resistive.
  • Lt decreases during injection of a sample, the plasma is cooled and shrinks. The coupling factor decreases causing L t to increase.
  • a second form of compensation stabilizes the magnitude of the oscillations in the resonant circuit.
  • changing the load resistance in the resonsant circuit i.e. the plasma
  • the amplitude of the oscillations tends to decrease because the added resistance causes more energy to be consumed in the resonant circuit than is supplied from the plate voltage source. This makes the minimum plate voltage, e p (min) larger, increasing the amplitude of the plate current (ip) pulses and resulting in the resonant circuit receiving additional energy.
  • the amplitude of oscillation assumes a new equilibrium point in which the enlarged plate current impulses supply sufficient energy to the resonant circuit to stabilize the amplitude.
  • a small percentage change in ep peak-to-peak amplitude causes a much greater percentage change in ep ( m in) resulting in a boot strap effect to stabilize the amplitude.
  • the plot of e represents the grid voltage.
  • the third form of stabilization is provided by the fact that when the L t of FIG. 6 changes, the inductance of the resonant circuit changes. However, the current in the resonant circuit will remain at a maximum by slightly shifting the fundamental frequency. This insures the basic system stays "in tune" over the required operating conditions.
  • rf amplifier 29 can oscillate and deliver substantially full power to work coil 19 even when un-ionized argon gas is present in torch 7.
  • Full power is available to ignite and sustain the plasma without complex regulation of power frequency and phase relation during the ignition process.
  • small frequency shifts automatically occur to maintain the rf power delivered to the plasma.
  • the configuration advantageously produces only a very small frequency shift, and the rf output easily stays within the allowed bandwidth.
  • the maximum frequency shift is typically limited to less than about 100 KHz.
  • FIG. 5 shows a schematic diagram of a power supply employed in the invention. Control of the rf output of the rf excitor, or head unit, is accomplished by varying the high voltage output of the power supply. This is accomplished by changing the DC current in the control winding of saturable reactor Ll. Increasing the current causes the iron core of the saturable reactor to saturate allowing a greater percentage of the input power to be applied to the primary of transformer T2, thereby increasing the high voltage output.
  • Line power enters through line filter FL1 and is protected and switched by front panel circuit breaker CBl. For control purposes, this power is applied through fuse Fl to supply primary power for the filament transformer in the rf head as well as primary power for the control transformer Tl.
  • Control transformer Tl provides power for relay and plasma head control and the fan circuits as well as power for use by the regulator board.
  • Main power is switched by relay Kl which is controlled by front panel push button switches Sl and S2.
  • the front panel pilot lights indicate the presence of control power and the position of relay Kl. Power from relay Kl is controlled by saturable reactor Ll and is applied through the front panel tab select run-start switch S3 to the primary of high voltage transformer T2.
  • transformer T2 The output of transformer T2 is rectified by the voltage doubler circuit consisting of rectifiers CR1 and CR2 and capacitor bank C90-C99.
  • the output voltage is transferred to the rf exciter generator head 2 by cable Wl.
  • the return current from the rf head unit is measured through resistor 13 and overload relay K2. Overload currents cause the contact of K2 to open, thereby dropping out relay Kl which turns off the high voltage.
  • the regulator printed circuit (PC) board generates the DC currents to control the saturable reactor.
  • PC printed circuit
  • two external inputs provide input signals for use by the regulator board.
  • the first, potentiometer R6 located on the front panel provides an input to set the high voltage level of the power supply unit.
  • the second, a percentage of the output voltage is generated by a voltage divider comprised of resistors R14-R23 along with resistor R24.
  • Potentiometer R6 acting through resistor R5 and transistor Q2 controls the set point of a three terminal regulator Ql.
  • Input power for Ql is generated from the low voltage winding of Tl, full-wave rectifier CR1 and capacitor Cl.
  • the output of Ql is connected to the control winding of the saturable reactor Ll to directly control the high voltage level. Regulation of the high voltage level is accomplished by feeding back the voltage divider signal to operational amplifier Q3 by resistors R2 and R3. Since the junction of R2 and R3 are connected to the negative terminal of Q3, the output of Q3 changes inversely with changes in the high voltage level.
  • the output of Q3 is applied through Q2 to the control input of Ql closing the inverse feed back loop.
  • a connector J2 is provided to supply 110V power and interlock with the plasma torch enclosure system.
  • a terminal of connector J2 is interlocked with the plasma torch enclosure system to shut down the rf power under certain error conditions, such as low cooling water pressure, and low argon gas pressure.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Electromagnetism (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)
  • Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
  • Plasma Technology (AREA)
EP84101792A 1983-03-08 1984-02-21 Plasma excitation system Withdrawn EP0122403A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US47338683A 1983-03-08 1983-03-08
US473386 1983-03-08

Publications (1)

Publication Number Publication Date
EP0122403A1 true EP0122403A1 (en) 1984-10-24

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EP84101792A Withdrawn EP0122403A1 (en) 1983-03-08 1984-02-21 Plasma excitation system

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EP (1) EP0122403A1 (ja)
JP (1) JPS59171838A (ja)
ZA (1) ZA841218B (ja)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3638880A1 (de) * 1985-11-15 1987-05-27 Paar Anton Kg Verfahren und vorrichtung zum erzeugen eines hf-induzierten edelgasplasmas
EP0280044A2 (en) * 1987-01-26 1988-08-31 Mitsubishi Denki Kabushiki Kaisha Plasma apparatus
EP0281157A2 (en) * 1987-03-06 1988-09-07 The Perkin-Elmer Corporation Power system for inductively coupled plasma torch
DE4037698A1 (de) * 1990-02-26 1991-08-29 Leco Corp Mehrfrequenzaktivierungs-steuerungsschaltung fuer einen induktiv gekoppelten plasmagenerator
EP0450727A1 (en) * 1990-04-06 1991-10-09 Koninklijke Philips Electronics N.V. Plasma generator
FR2683422A1 (fr) * 1991-10-31 1993-05-07 Rc Durr Sa Generateur haute frequence pour torche a plasma.
EP0602764A1 (en) * 1992-12-17 1994-06-22 FISONS plc Inductively coupled plasma spectrometers and radio - frequency power supply therefor
US6325799B1 (en) 1997-04-24 2001-12-04 Gyrus Medical Limited Electrosurgical instrument
CN109921745A (zh) * 2019-04-02 2019-06-21 无锡旭洲智能科技有限公司 侧面输出型射频谐振发生器及杀虫杀菌装置

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP6048068B2 (ja) * 2012-10-25 2016-12-21 株式会社島津製作所 プラズマ用高周波電源及びそれを用いたｉｃｐ発光分光分析装置

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3467471A (en) * 1963-10-21 1969-09-16 Albright & Wilson Mfg Ltd Plasma light source for spectroscopic investigation
US3958883A (en) * 1974-07-10 1976-05-25 Baird-Atomic, Inc. Radio frequency induced plasma excitation of optical emission spectroscopic samples

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5292500A (en) * 1976-01-29 1977-08-03 Yousuke Saida Alarm

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3467471A (en) * 1963-10-21 1969-09-16 Albright & Wilson Mfg Ltd Plasma light source for spectroscopic investigation
US3958883A (en) * 1974-07-10 1976-05-25 Baird-Atomic, Inc. Radio frequency induced plasma excitation of optical emission spectroscopic samples

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
ANALYTICA CHIMICA ACTA, no. 74, 1975, Amsterdam S. GREENFIELD et al. "Automatic multi-sample simultaneous multi-element analysis with a H.F. plasma torch and direct reading spectrometer", pages 225-245 *
PHILIPS TECHNISCHE RUNDSCHAU, vol. 33, no. 2, 1973/74 P.W.J.M. BOUMANS et al. "Eine stabilisierte HF-Argonplasmafackel für Emissionsspektroskopie", pages 51-61 *

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3638880A1 (de) * 1985-11-15 1987-05-27 Paar Anton Kg Verfahren und vorrichtung zum erzeugen eines hf-induzierten edelgasplasmas
EP0674471A1 (en) * 1987-01-26 1995-09-27 Mitsubishi Denki Kabushiki Kaisha Plasma apparatus
EP0280044A3 (en) * 1987-01-26 1991-10-23 Mitsubishi Denki Kabushiki Kaisha Plasma apparatus
EP0280044A2 (en) * 1987-01-26 1988-08-31 Mitsubishi Denki Kabushiki Kaisha Plasma apparatus
EP0281157A2 (en) * 1987-03-06 1988-09-07 The Perkin-Elmer Corporation Power system for inductively coupled plasma torch
EP0281157A3 (en) * 1987-03-06 1990-03-28 The Perkin-Elmer Corporation Power system for inductively coupled plasma torch
DE4037698A1 (de) * 1990-02-26 1991-08-29 Leco Corp Mehrfrequenzaktivierungs-steuerungsschaltung fuer einen induktiv gekoppelten plasmagenerator
EP0450727A1 (en) * 1990-04-06 1991-10-09 Koninklijke Philips Electronics N.V. Plasma generator
FR2683422A1 (fr) * 1991-10-31 1993-05-07 Rc Durr Sa Generateur haute frequence pour torche a plasma.
EP0602764A1 (en) * 1992-12-17 1994-06-22 FISONS plc Inductively coupled plasma spectrometers and radio - frequency power supply therefor
US6325799B1 (en) 1997-04-24 2001-12-04 Gyrus Medical Limited Electrosurgical instrument
CN109921745A (zh) * 2019-04-02 2019-06-21 无锡旭洲智能科技有限公司 侧面输出型射频谐振发生器及杀虫杀菌装置
CN109921745B (zh) * 2019-04-02 2023-07-18 无锡旭洲智能科技有限公司 侧面输出型射频谐振发生器及杀虫杀菌装置

Also Published As

Publication number Publication date
ZA841218B (en) 1984-09-26
JPS59171838A (ja) 1984-09-28

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