WO1996019716A1 - Spectrometer with discharge limiting means - Google Patents
Spectrometer with discharge limiting means Download PDFInfo
- Publication number
- WO1996019716A1 WO1996019716A1 PCT/AU1995/000856 AU9500856W WO9619716A1 WO 1996019716 A1 WO1996019716 A1 WO 1996019716A1 AU 9500856 W AU9500856 W AU 9500856W WO 9619716 A1 WO9619716 A1 WO 9619716A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- inductively coupled
- coupled plasma
- spectrometer according
- shielding
- circuit
- Prior art date
Links
- 238000005070 sampling Methods 0.000 claims abstract description 27
- 238000009616 inductively coupled plasma Methods 0.000 claims abstract description 25
- 230000003287 optical effect Effects 0.000 claims abstract description 15
- 239000003990 capacitor Substances 0.000 claims description 9
- 239000002826 coolant Substances 0.000 claims description 6
- 230000006698 induction Effects 0.000 description 8
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 6
- 239000007789 gas Substances 0.000 description 5
- 230000008878 coupling Effects 0.000 description 4
- 238000010168 coupling process Methods 0.000 description 4
- 238000005859 coupling reaction Methods 0.000 description 4
- 238000001514 detection method Methods 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 229910052786 argon Inorganic materials 0.000 description 3
- 238000002354 inductively-coupled plasma atomic emission spectroscopy Methods 0.000 description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 2
- 238000007792 addition Methods 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 230000001965 increasing effect Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 229910052709 silver Inorganic materials 0.000 description 2
- 239000004332 silver Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 230000001668 ameliorated effect Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 238000001636 atomic emission spectroscopy Methods 0.000 description 1
- 238000000889 atomisation Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 238000009966 trimming Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J49/00—Particle spectrometers or separator tubes
- H01J49/02—Details
- H01J49/06—Electron- or ion-optical arrangements
- H01J49/067—Ion lenses, apertures, skimmers
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
- G01J3/28—Investigating the spectrum
- G01J3/443—Emission spectrometry
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J49/00—Particle spectrometers or separator tubes
- H01J49/02—Details
- H01J49/10—Ion sources; Ion guns
- H01J49/105—Ion sources; Ion guns using high-frequency excitation, e.g. microwave excitation, Inductively Coupled Plasma [ICP]
Definitions
- This invention relates to an inductively coupled plasma spectrometer.
- the invention is advantageously applied to an optical emission spectrometer (ICP- OES) wherein the plasma torch and the optical system of the spectrometer may be axially aligned and will be described herein in that context. Nevertheless it is to be appreciated that it is not thereby limited to such applications.
- ICP- OES optical emission spectrometer
- radio frequency (RF) energy is inductively coupled into a gas, such as for example argon, which is caused to flow through the torch to generate a plasma discharge.
- the plasma is used to atomise and excite a sample that is injected into the plasma to cause the emission of light at wave lengths which are characteristic of the atomic composition of the sample.
- the emitted light is detected and measured to obtain an analysis of the sample.
- Analytical detection limits are improved in optical emission spectrometers in which the cloud of excited atoms generated in the plasma is viewed by an optical detection system of the spectrometer axially along the central axis of the plasma torch rather than perpendicular to that axis as in some known instruments.
- an axially aligned optical system needs to be protected from the heat and contaminants in the plasma exhaust. This may be done by interposing a shield that includes a sampling or viewing port or orifice between the plasma "tail" and the entrance end of the optical system.
- a shield is best if made of a conductive metal, as this allows it to be adapted, for example by the incorporation of a cooling system, to minimise damage which may be caused to the shield or its insulating support structure by heat from the plasma or hot gases leaving the plasma.
- an object of the present invention is to provide an inductively coupled plasma spectrometer in which the problem of an electrical discharge occurring between the plasma and the sampling shield is eliminated or at least substantially ameliorated.
- a similar discharge problem can occur between the plasma and a cone containing a sampling orifice in inductively coupled plasma mass spectrometers (ICP-MS).
- ICP mass spectrometers by reducing the potential difference between the plasma and the sampling cone, for example by special induction coil arrangements as in United States Patents 5194731 and 4501965 (RE 33386) or by biasing the cone as in United States Patent 4682026.
- these are relatively costly solutions which may be commercially viable for ICP mass spectrometers in circumstances where the arcing problem is especially critical in these spectrometers.
- the present invention may offer a solution to the problem of arcing which is realisable in a simple and cost effective manner in ICP-OES as well as in ICP-MS instruments.
- the invention provides an inductively coupled plasma spectrometer including shielding/sampling means located between a plasma torch and an optical system of the spectrometer, wherein said shielding/sampling means is associated with an enclosure for the plasma torch such that a relatively high impedance path is established for limiting flow of electrical current between said shielding/sampling means and said enclosure.
- Flow of electrical current between the shielding/sampling means should be limited below a level which would sustain a discharge. It has been shown that isolating the shielding/sampling means from the enclosure by an insulating medium does not provide the requisite high impedance as reactance of the capacitance between the shielding/sampling means and the enclosure at the frequency of the plasma RF source is typically too low.
- the high impedance path includes a circuit that is resonant at the frequency cf the RF supplied to the induction coil of the plasma torch.
- the circuit includes an inductance chosen such that it and the capacitance between the shielding/sampling means and the plasma system enclosure wiir form a parallel resonant circuit at the frequency of the RF supply.
- the circuit may also include a variable inductor or capacitor, for example a trimming capacitor, for tuning the circuit.
- the inductance includes an air-cored inductor.
- the circuit for establishing a high impedance path between the shielding/sampling means and plasma system enclosure is provided by an air-cored inductor which is also used to supply a coolant to the shielding/sampling means.
- the inductor is formed from hollow conductive tubing, for example of silver plated copper, through which a coolant such as for example water is supplied for circulation through ducting in or associated with the shielding/sampling means before it passes out of the system via a suitable outlet.
- a parallel resonant circuit as provided by the invention has a high impedance at the resonant frequency which is given by the product of the inductive reactance of the inductor and the quality factor (Q) of the tuned circuit. For example, at a frequency of between 27 to 100 MHz, which is a typical for the RF supply to the induction coil of the plasma torch, a Q in excess of 400 may be readily realised. This may establish a high impedance at the resonant frequency such as may substantially reduce a discharge current from the plasma in comparison to a spectrometer not having the parallel resonant circuit.
- FIG. 1 is a schematic diagram showing the physical location and electrical connection of a shielding/sampling cone 1 within an inductively coupled plasma optical emission spectrometer according to an embodiment of the present invention.
- the invention includes a conductive metal cone 1 having a viewing aperture 2, interposed between a plasma torch 3 and an optical system 4.
- the torch 3, cone aperture 2 and optical system 4 are aligned such that a cloud of excited atoms from a sample, as generated in the plasma torch, is viewed axially along the central axis 5 of the torch rather than perpendicularly to that axis as in conventional systems.
- This axial viewing arrangement improves analytical detection limits of ICP-OES instruments because emissions from the excited atoms are viewed more efficiently than is the case if a side view is taken.
- the optical viewing system and associated detection and analytical componentry and circuits as such are generally the same in the axial system as in the conventional perpendicular viewing system. Such systems, componentry and circuits are known in the art and are thus not described in detail herein.
- Plasma torch 3 includes inlets 6 for supplying a plasma forming gas, which is preferably argon; and an induction coil 7 for inductively coupling RF energy, preferably at a free running frequency of 40 Mhz (nominal), into the gas flowing through the torch to generate a plasma.
- a suitable RF supply (not shown) is connected to induction coil 7.
- a sample may be injected axially through an inlet 8 into the torch for atomisation in the plasma.
- an air-cored inductor 11 is also connected between the cone 1 and enclosure 9, its inductance being such that it forms a parallel resonant circuit with capacitor 10 at the frequency of the RF supply to induction coil 7.
- the parallel resonant circuit 10-11 provides a relatively high impedance path between cone 1 and enclosure 9 which acts to suppress or limit flow of electrical current from the plasma such that a discharge to cone 1 is avoided.
- a variable capacitor may be connected across the inductor 11 (in which case it may be in parallel with capacitor 10 or may replace capacitor 10) for adjusting the total capacitance to allow the circuit to be tuned to resonance.
- inductor 11 may be constructed such that its inductance is adjustable for tuning purposes. In one embodiment this may be achieved by deforming the hollow tubing from which the inductor is formed.
- a preferred construction may be to manufacture inductor 11 to provide the correct inductance to resonate with capacitor 10 at the plasma torch operating frequency.
- Cone 1 is preferably made of metal, for example nickel, and is in heat conducting relationship with a heat sink (not shown) for extracting heat from the cone.
- the heat sink may include a duct for passage of a coolant, preferably water, therethrough.
- the tubing for supply of the coolant to the heat sink associated with cone 1 may be coiled so as to form inductor 11.
- the invention offers a simple and cost effective means for suppressing arcing to the cone in that two functions may be served by one component.
- a supply of argon gas may be directed to pass out of aperture 2 in cone 1 , as indicated by arrows 12, to give added protection for the optical system 4 from the plasma exhaust.
- an inductor 11 needs to have an inductance of about 440 nH for realisation of the invention. This may be formed by suitably coiling a coolant inlet tube of for example silver plated copper and of about 4 mm OD. In other instruments the inductance may range in value from about 60 to 700 nH.
- the resonant circuit can be detuned from the frequency of the plasma RF source or alternatively the quality factor (Q) of the tuned circuit may be decreased.
- the frequency of the resonant circuit may be detuned so that it lies above or below the frequency of the RF source.
- this may have the effect of reducing substantially the value of the high impedance path between cone 1 and enclosure 9.
- the resonant frequency can be decreased by switching additional tuning capacitance across inductor 11 to lower the resonant frequency.
- the value of the high impedance path between shielding/sampling cone 1 and enclosure 9 may alternatively be reduced by reducing the quality factor of the tuned circuit.
- the quality factor may be reduced by reducing the value of inductor 11 or by increasing the resistance of the resonant circuit.
- the latter may be achieved by switching a suitable resistance across inductor 11 , by temporarily connecting cone 1 to enclosure 9 or by providing another inductor mutually coupled to an inductor forming part of the cone resonant circuit which can be short circuited by an appropriate switch.
- the invention described herein is susceptible to variations, modifications and/or additions other than those specifically described and it is to be understood that the invention includes all such variations, modifications and/or additions which fall within the spirit and scope of the above description.
Abstract
Description
Claims
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE69530002T DE69530002T2 (en) | 1994-12-20 | 1995-12-19 | SPECTROMETER WITH DISCHARGE-LIMITING AGENTS |
US08/849,943 US5841531A (en) | 1994-12-20 | 1995-12-19 | Spectrometer with discharge limiting means |
AU43217/96A AU696281B2 (en) | 1994-12-20 | 1995-12-19 | Spectrometer with discharge limiting means |
EP95941976A EP0799408B1 (en) | 1994-12-20 | 1995-12-19 | Spectrometer with discharge limiting means |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AUPN0152A AUPN015294A0 (en) | 1994-12-20 | 1994-12-20 | Emission spectrometer |
AUPN0152 | 1994-12-20 | ||
AUPN047895 | 1995-01-11 | ||
AUPN0478 | 1995-01-11 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1996019716A1 true WO1996019716A1 (en) | 1996-06-27 |
Family
ID=25644831
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/AU1995/000856 WO1996019716A1 (en) | 1994-12-20 | 1995-12-19 | Spectrometer with discharge limiting means |
Country Status (4)
Country | Link |
---|---|
US (1) | US5841531A (en) |
EP (1) | EP0799408B1 (en) |
DE (1) | DE69530002T2 (en) |
WO (1) | WO1996019716A1 (en) |
Families Citing this family (17)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6122050A (en) * | 1998-02-26 | 2000-09-19 | Cornell Research Foundation, Inc. | Optical interface for a radially viewed inductively coupled argon plasma-Optical emission spectrometer |
CA2595230C (en) * | 2005-03-11 | 2016-05-03 | Perkinelmer, Inc. | Plasmas and methods of using them |
US7733482B2 (en) * | 2007-03-26 | 2010-06-08 | Ruda Harry E | System and method for determining at least one constituent in an ambient gas using a microsystem gas sensor |
JP2011522381A (en) | 2008-05-30 | 2011-07-28 | コロラド ステート ユニバーシティ リサーチ ファンデーション | Plasma-based chemical source apparatus and method of use thereof |
WO2011123124A1 (en) | 2010-03-31 | 2011-10-06 | Colorado State University Research Foundation | Liquid-gas interface plasma device |
US8994270B2 (en) | 2008-05-30 | 2015-03-31 | Colorado State University Research Foundation | System and methods for plasma application |
JP2011521735A (en) | 2008-05-30 | 2011-07-28 | コロラド ステート ユニバーシティ リサーチ ファンデーション | System, method and apparatus for generating plasma |
US8222822B2 (en) | 2009-10-27 | 2012-07-17 | Tyco Healthcare Group Lp | Inductively-coupled plasma device |
AU2010349785B2 (en) | 2010-03-31 | 2014-02-27 | Colorado State University Research Foundation | Liquid-gas interface plasma device |
EP2568276B1 (en) | 2011-09-06 | 2016-11-23 | Spectro Analytical Instruments GmbH | Plasma emission transfer and modification device |
US9532826B2 (en) | 2013-03-06 | 2017-01-03 | Covidien Lp | System and method for sinus surgery |
US9555145B2 (en) | 2013-03-13 | 2017-01-31 | Covidien Lp | System and method for biofilm remediation |
JP6512307B2 (en) * | 2015-12-24 | 2019-05-15 | 株式会社島津製作所 | ICP mass spectrometer |
DE102016200517A1 (en) * | 2016-01-18 | 2017-07-20 | Robert Bosch Gmbh | Microelectronic component arrangement and corresponding production method for a microelectronic component arrangement |
GB2585327B (en) * | 2018-12-12 | 2023-02-15 | Thermo Fisher Scient Bremen Gmbh | Cooling plate for ICP-MS |
CN109950124A (en) * | 2019-04-17 | 2019-06-28 | 大连民族大学 | A kind of radio-frequency coil for eliminating inductivity coupled plasma mass spectrometry secondary discharge |
US11145501B2 (en) | 2020-02-20 | 2021-10-12 | Perkinelmer, Inc. | Thermal management for instruments including a plasma source |
Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4501965A (en) * | 1983-01-14 | 1985-02-26 | Mds Health Group Limited | Method and apparatus for sampling a plasma into a vacuum chamber |
US4682026A (en) * | 1986-04-10 | 1987-07-21 | Mds Health Group Limited | Method and apparatus having RF biasing for sampling a plasma into a vacuum chamber |
EP0252475A2 (en) * | 1986-07-07 | 1988-01-13 | Shimadzu Corporation | Inductively-coupled radio frequency plasma mass spectrometer |
US5194731A (en) * | 1990-07-24 | 1993-03-16 | Varian Associates, Inc. | Inductively coupled plasma spectroscopy |
WO1993021653A1 (en) * | 1992-04-09 | 1993-10-28 | Clemson University | Radio-frequency powered glow discharge device and method with high voltage interface |
US5334834A (en) * | 1992-04-13 | 1994-08-02 | Seiko Instruments Inc. | Inductively coupled plasma mass spectrometry device |
EP0614210A1 (en) * | 1993-03-05 | 1994-09-07 | Varian Australia Pty. Ltd. | Plasma mass spectrometry |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3123843B2 (en) * | 1992-12-17 | 2001-01-15 | 日本電子株式会社 | Sample vaporizer using plasma flame |
-
1995
- 1995-12-19 WO PCT/AU1995/000856 patent/WO1996019716A1/en active IP Right Grant
- 1995-12-19 EP EP95941976A patent/EP0799408B1/en not_active Expired - Lifetime
- 1995-12-19 US US08/849,943 patent/US5841531A/en not_active Expired - Lifetime
- 1995-12-19 DE DE69530002T patent/DE69530002T2/en not_active Expired - Lifetime
Patent Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4501965A (en) * | 1983-01-14 | 1985-02-26 | Mds Health Group Limited | Method and apparatus for sampling a plasma into a vacuum chamber |
US4682026A (en) * | 1986-04-10 | 1987-07-21 | Mds Health Group Limited | Method and apparatus having RF biasing for sampling a plasma into a vacuum chamber |
EP0252475A2 (en) * | 1986-07-07 | 1988-01-13 | Shimadzu Corporation | Inductively-coupled radio frequency plasma mass spectrometer |
US5194731A (en) * | 1990-07-24 | 1993-03-16 | Varian Associates, Inc. | Inductively coupled plasma spectroscopy |
WO1993021653A1 (en) * | 1992-04-09 | 1993-10-28 | Clemson University | Radio-frequency powered glow discharge device and method with high voltage interface |
US5334834A (en) * | 1992-04-13 | 1994-08-02 | Seiko Instruments Inc. | Inductively coupled plasma mass spectrometry device |
EP0614210A1 (en) * | 1993-03-05 | 1994-09-07 | Varian Australia Pty. Ltd. | Plasma mass spectrometry |
Non-Patent Citations (2)
Title |
---|
PATENT ABSTRACTS OF JAPAN, E-683, page 34; & JP,A,63 168 956, (YOKOGAWA ELECTRIC CORP), 12 July 1988. * |
See also references of EP0799408A4 * |
Also Published As
Publication number | Publication date |
---|---|
EP0799408A1 (en) | 1997-10-08 |
DE69530002D1 (en) | 2003-04-24 |
US5841531A (en) | 1998-11-24 |
EP0799408A4 (en) | 2000-02-23 |
DE69530002T2 (en) | 2004-01-08 |
EP0799408B1 (en) | 2003-03-19 |
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