WO1995025951A1 - Plasma manipulator - Google Patents
Plasma manipulator Download PDFInfo
- Publication number
- WO1995025951A1 WO1995025951A1 PCT/EP1995/000447 EP9500447W WO9525951A1 WO 1995025951 A1 WO1995025951 A1 WO 1995025951A1 EP 9500447 W EP9500447 W EP 9500447W WO 9525951 A1 WO9525951 A1 WO 9525951A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- plasma
- observation
- emission
- manipulator
- analysis according
- Prior art date
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
- G01N21/71—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light thermally excited
- G01N21/73—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light thermally excited using plasma burners or torches
-
- 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
- H05H1/0006—Investigating plasma, e.g. measuring the degree of ionisation or the electron temperature
- H05H1/0012—Investigating plasma, e.g. measuring the degree of ionisation or the electron temperature using electromagnetic or particle radiation, e.g. interferometry
- H05H1/0037—Investigating plasma, e.g. measuring the degree of ionisation or the electron temperature using electromagnetic or particle radiation, e.g. interferometry by spectrometry
Definitions
- the invention relates to a device for forming the observation zone of a plasma area for optical emission spectral analysis.
- the device for plasma formation is intended to separate that area from a non-current-carrying plasma which contains an analysis sample and which at the same time ensures low intensities of the spectral background radiation with the highest possible analytical emission signal.
- the emission signals are to be stabilized against fluctuations and the ambient air is to be kept away from the light path between the observation zone of the plasma and the spectrometer used.
- Various types of plasma radiation sources for use in emission analysis are known.
- An analysis sample is usually introduced into the plasma as an aerosol with the aid of a carrier gas, evaporated, dissociated, partially ionized there and the free atoms and ions excited to produce optical emissions.
- the measurement of the emitted radiation is usually carried out in a non-current-carrying area of the plasma in order to keep influences of the sample matrix as low as possible.
- radiation sources are the disc-stabilized arc, the inductively coupled plasma (ICP) and the microwave-excited plasma.
- S / N signal-to-noise ratio
- S / N the quotient of the spectral line intensity of the species to be detected and the emission of the spectral background occurring in the relevant spectral interval.
- S / N strongly depends on the type of optical observation. For example, when observing perpendicularly to the plasma axis in ICP, one finds a distance from the excitation coil that is dependent on the analysis element under consideration and at which S / N becomes maximum (PWJM Boumans, Ed., Inductively Coupled Plasma Spectroscopy, John Wiley & Sons, New York, 1987) .
- the emission of molecules contributes to increasing the background.
- the intensities of both types of background radiation increase with the plasma temperature more than the desired light intensity.
- the optimal temperatures for different emission lines of atoms and ions used for the analysis differ considerably. Zones with different temperatures are detected both when observing the plasma perpendicularly and parallel to the axis of the plasma. This fact limits the achievable S / N.
- the object of the invention is to manipulate non-current-carrying plasmas in such a way that the background radiation is reduced and the signal-to-noise ratio of the analytical measurement is increased.
- the object is achieved in that the sub-area of the plasma which is optimal for emission measurement is masked out, the observation takes place in a volume area largely shielded from environmental influences, and the plasma composition can also be optimized by applying electrical or magnetic fields.
- the invention leads to a significant improvement in the detection capacity of the analytical method.
- a cooled orifice is attached, which in particular only allows the optical part to pass through the central part of the plasma which is optimal for the emission measurements.
- there is a chamber which allows observation of the separated plasma area perpendicular to its axis or in the axial direction.
- the path between the plasma area and the measuring device is flushed with a suitable gas, preferably the carrier gas of the plasma, to ensure optical transmission.
- a suitable gas preferably the carrier gas of the plasma
- Cooled aperture, observation chamber and connection device to the spectrometer form a plasma manipulator.
- An electrical potential applied to the inlet aperture relative to the plasma potential results in an optimization of S / N due to the influence on the electron and ion concentration.
- Electrodes or magnetic pole shoes attached within the manipulator enable the generation of electric or magnetic fields in front of or within the observation zone, which can also be used to optimize S / N by changing the charge carrier concentration in the plasma. If AC voltage is applied to the manipulator and / or the electrodes located inside, the line and background intensity are modulated in the rhythm of this AC voltage.
- the phase-dependent evaluation of the then modulated signals enables a distinction to be made between useful and interference signals and thus the optimization of S / N.
- a pump is advantageously used to generate the negative pressure, the pressure side of the pump being returned to the analysis plasma, in particular to the cooling gas flow, in order to achieve better utilization of the analysis plasma.
- the specific configuration of the device according to the invention and the selection of the operating parameters, such as plasma conduction, gas throughputs, distance between plasma generation device and plasma manipulator including the selected electrical potentials depend on the one hand on the samples to be analyzed and on the other hand the required detection limits.
- the plasma axis can be arranged both vertically and horizontally.
- the plasma For a high signal to noise ratio, it can be advantageous, for example, to observe the plasma with the observation device at an angle of 10 to 170 degrees, preferably between 45 and 135 degrees, against the axis of propagation, in certain applications. In other applications, it may be necessary to arrange the observation device in the direction of propagation of the plasma and thus to select a so-called end-on observation position. In this case, the conical bore of the cooled screen can also be mapped onto an intermediate screen.
- a voltage can be applied to the ICP burner tube and the aperture of the plasma manipulator. This can either modulate the plasma itself electrically, or compensate for an electrical potential that builds up between the plasma generator and the plasma manipulator.
- Geometrically favorable ratios result when an inlet screen with a thickness comparable to its diameter is present on the plasma manipulator and the observation volume has a larger diameter than the screen.
- electrodes or pole shoes are arranged between the inlet aperture and the observation volume, in particular in the area of the observation volume, as a means for generating an electrical and / or a magnetic field, particularly if a coil is present in the space area adjacent to the plasma beam formed, the plasma can be present Observation volume be formed electrically or magnetically.
- An alternating voltage can be applied to the electrodes, the signal detection in the spectrometer being synchronized with this alternating voltage and the signal to noise ratio thereby being improved in a manner known per se.
- the modulation of the plasma is chosen so that the part of the signal that is significant for the emission under consideration is changed with the modulation, while the background remains largely constant. A background correction of the signal obtained can then be carried out on the basis of the constant portion of the emission.
- the Pla ⁇ mamanipulator can a diaphragm having a pipe socket on the central Au ⁇ Deletesort • for Pla ⁇ ma ⁇ trahls Have a pump connected so that carrier gases from the plasma or purge gases from the plasma manipulator can be drawn off and reused. It is advantageous if the ICP burner tube is brought particularly close to the plasma manipulator, so that the flushing gas or the carrier gas comes into contact with the surrounding atmosphere as little as possible. In an extreme embodiment of this construction principle, the ICP burner tube (also torch tube) can be directly connected to the plasma manipulator, for example welded or screwed to it, so that the observed plasma and the purge gas cannot come into contact with the outside air at all. The suction is then advantageously carried out via an annular gap arranged in the plasma manipulator.
- the plasma torch to be observed can also be manipulated in that an inert gas flow coaxial to the plasma torch and opposite to its direction of flow emerges from the plasma manipulator, thus reducing the actually light-emitting length of the plasma torch. It can be achieved in this way that the plasma torch is funnel-shaped apart in the area in which it meets the purge gas and the temperature gradient in this area becomes particularly large. This has the consequence that when measuring elements such as. B. cadmium has only a very specific, short area of the plasma torch which has the temperature required for UV emission and is immediately followed (in the direction of spreading of the plasma) by a cold area which in essence cannot emit any disturbing UV light.
- the flow of the gas fed in countercurrent allows the length of the plasma torch observed to be set and the UV-emitting region to be selected in an element-specific manner.
- a short plasma torch would be used for elements high excitation energy are preferred, while a long plasma torch is optimal for elements of low excitation energy.
- Figure 1 a first exemplary embodiment
- FIG. 2 a second embodiment
- FIG. 3 a third exemplary embodiment
- FIG. 4 an exemplary embodiment with an almost completely shielded plasma torch.
- FIG. 1 shows a first embodiment of a simple variant of the device according to the invention. Figure 1 is explained below:
- the ICP burner tube 1 with the concentric inner aerosol feed tube is from the
- High-frequency excitation coil 2 surround. Approximately 5 to 10 mm above the excitation coil there is the axially arranged plasma manipulator 4 with the observation nozzle 3. Connections for water cooling on the manipulator 4 are omitted for the sake of clarity.
- the electrical potential of the plasma manipulator 4 relative to the excitation coil is empirically optimized with the voltage source U.
- the plasma located above the burner tube 1 is divided by the conical plasma manipulator 4 into a central beam 6 along the plasma axis 7 and a deflected beam 5.
- the central beam 6 has an approximate diameter between 2 and 6 mm, corresponding to the aperture of the plasma manipulator 4.
- the emission radiation of the central beam 6 passes through the observation nozzle 3 into an optical spectrometer, which is omitted for the sake of clarity.
- an optical spectrometer For measurements in the ultraviolet spectral range, it is advisable to purge the observation port 3 from the spectrometer with the plasma carrier gas.
- the central bore of the plasma manipulator is selected in such a way that the central region of the plasma containing the atoms to be detected is let through in accordance with the dimensions of the ICP burner and the outer annular region of higher temperature and stronger background emission is kept away from the observation zone. This increases the S / N of this arrangement compared to the usual free plasma torch.
- FIG. 2 shows a second variant of the plasma manipulator.
- the observation volume in the plasma manipulator 4 here is expanded compared to the inlet aperture 8 and enables the introduction of deflection electrodes 9 and 10.
- the latter as shown in FIG. 2, can be attached both directly in front of the observation volume and to the side thereof.
- a voltage applied to the electrodes 9 and 10 removes charge carriers from the plasma beam and thereby reduces the charge Underground emission, while the atomic emission initially remains unchanged.
- the outlet orifice 11 prevents atmospheric constituents from entering the observation zone.
- a connector 12 for connecting a pump can also be inserted into this diaphragm.
- the observation port 3 is expediently closed off in an gastight manner with respect to the spectrometer by means of an optical window 13.
- connection of a pump to the nozzle 3 creates a negative pressure in the plasma manipulator and an increase in the emission signal due to the increased throughput of the central plasma beam.
- a means for generating a magnetic field in particular a coil, can also be attached at this point or in the direction of flow behind it.
- the coil is preferably arranged on a magnetic core (yoke), the coil being outside the plasma manipulator.
- the pressure side of the pump is returned to the analysis plasma in all three embodiments, in particular to the cooling gas flow.
- FIG. 3 Another variant of the invention is shown in FIG. 3.
- the axis of the observation port 3 coincides with the axis 7 of the Analyze plasmas together.
- an imaging lens can also be used to optimize the transfer of light from the cooled aperture to the spectrometer.
- a flushing gas supply 14 is provided on the side of the plasma manipulator 4, so that the flushing gas emerging from the orifice 8 prevents the central part of the analysis plasma from penetrating.
- the central bundle 15 of the optical emission of the plasma reaches the observation device.
- the variant according to FIG. 3 represents an arrangement which is easy to implement and which is at the same time particularly suitable for samples with matrix, since no parts of the plate can get onto the screen 8 or into the plasma manipulator 4.
- the above-mentioned recycling of a part of the plasma gas is expedient, in that the gas is sucked off by means of a pump via a groove concentric with the orifice 8 and a separate bore in the plasma manipulator 4 and fed to the plasma burner 1.
- this part of the device has been omitted in FIG. 3.
- FIG. 1 A further embodiment of the plasma manipulator according to the invention is shown in FIG. 1
- the ICP burner tube 1 can be brought up to the plasma manipulator 4 for example, they also bear directly against the plasma manipulator 4.
- An inert gas for example argon, flows through the nozzle 3 towards the plasma torch which flows from bottom to top in FIG.
- the inert gas flow exits through the opening of the diaphragm 8 and hits the carrier gas flow of the plasma torch concentrically there.
- the plasma torch is pressed together in a funnel shape and enters a suction device 16 in the form of an annular gap. Both the inert gas and the carrier gas of the plasma torch and the aerosol residues are sucked out through the annular gap.
- the cooled gas can then be cleaned and used again as the carrier gas. Because the ICP burner tube 1 essentially encloses the orifice 8 and the annular gap 16, the plasma flame can practically no longer come into contact with the surrounding atmosphere, so that disturbing interferences are excluded here.
- the thermal energy of the plasma torch is preferably dissipated by water cooling of the plasma manipulator 4.
- the spectrometer input can thus be arranged in the axis of the plasma torch, ie, centrally in the nozzle 3. This enables a so-called end-on observation of the central part of the ICP plasma.
- a particularly good selectivity for the individual elements to be considered results from the fact that the length of the plasma torch, more precisely, the central part of the plasma torch can be adjusted by the countercurrent which emerges from the orifice 8 and thus only that part of the plasma torch can be viewed that contains the emissions of interest.
- the plasma torch can be kept very short, so that only the hotter part is analyzed, while for the analysis of sodium the plasma torch can be kept longer, so that the cooler areas can be viewed optically with the sodium emission lines.
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- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Engineering & Computer Science (AREA)
- Spectroscopy & Molecular Physics (AREA)
- General Health & Medical Sciences (AREA)
- Plasma & Fusion (AREA)
- Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
- Toxicology (AREA)
- Electromagnetism (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)
- Plasma Technology (AREA)
- Crystals, And After-Treatments Of Crystals (AREA)
Abstract
Description
Claims
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08/549,851 US5731872A (en) | 1994-03-18 | 1995-02-08 | Plasma manipulator |
AT95909686T ATE211821T1 (de) | 1994-03-18 | 1995-02-08 | Plasma manipulator |
AU18489/95A AU1848995A (en) | 1994-03-18 | 1995-02-08 | Plasma manipulator |
DE59509986T DE59509986D1 (en) | 1994-03-18 | 1995-02-08 | Plasma manipulator |
EP95909686A EP0699300B1 (de) | 1994-03-18 | 1995-02-08 | Plasma manipulator |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DEP4409237.7 | 1994-03-18 | ||
DE4409237 | 1994-03-18 | ||
DE4419423A DE4419423A1 (de) | 1994-03-18 | 1994-06-03 | Plasma-Manipulator |
DEP4419423.4 | 1994-06-03 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1995025951A1 true WO1995025951A1 (de) | 1995-09-28 |
Family
ID=25934831
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/EP1995/000447 WO1995025951A1 (de) | 1994-03-18 | 1995-02-08 | Plasma manipulator |
Country Status (5)
Country | Link |
---|---|
US (1) | US5731872A (de) |
EP (1) | EP0699300B1 (de) |
AT (1) | ATE211821T1 (de) |
AU (1) | AU1848995A (de) |
WO (1) | WO1995025951A1 (de) |
Families Citing this family (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US9997325B2 (en) * | 2008-07-17 | 2018-06-12 | Verity Instruments, Inc. | Electron beam exciter for use in chemical analysis in processing systems |
WO2010056921A2 (en) * | 2008-11-14 | 2010-05-20 | Project Frog, Inc. | Smart multifunctioning building panel |
EP2568276B1 (de) | 2011-09-06 | 2016-11-23 | Spectro Analytical Instruments GmbH | Plasmaemissionsübertragungs- und -modifizierungsvorrichtung |
JP6339816B2 (ja) * | 2014-02-10 | 2018-06-06 | 株式会社Fuji | プラズマ処理判断システム |
US10327319B1 (en) * | 2016-05-25 | 2019-06-18 | Perkinelmer Health Sciences, Inc. | Counterflow sample introduction and devices, systems and methods using it |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0051152A1 (de) * | 1980-10-31 | 1982-05-12 | The Perkin-Elmer Corporation | Optische Kupplungseinrichtung |
US4902099A (en) * | 1987-12-18 | 1990-02-20 | Hitachi, Ltd. | Trace element spectrometry with plasma source |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5483337A (en) * | 1994-10-19 | 1996-01-09 | Barnard; Thomas W. | Spectrometer with selectable radiation from induction plasma light source |
-
1995
- 1995-02-08 AU AU18489/95A patent/AU1848995A/en not_active Abandoned
- 1995-02-08 EP EP95909686A patent/EP0699300B1/de not_active Expired - Lifetime
- 1995-02-08 US US08/549,851 patent/US5731872A/en not_active Expired - Lifetime
- 1995-02-08 WO PCT/EP1995/000447 patent/WO1995025951A1/de active IP Right Grant
- 1995-02-08 AT AT95909686T patent/ATE211821T1/de not_active IP Right Cessation
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0051152A1 (de) * | 1980-10-31 | 1982-05-12 | The Perkin-Elmer Corporation | Optische Kupplungseinrichtung |
US4902099A (en) * | 1987-12-18 | 1990-02-20 | Hitachi, Ltd. | Trace element spectrometry with plasma source |
Also Published As
Publication number | Publication date |
---|---|
US5731872A (en) | 1998-03-24 |
AU1848995A (en) | 1995-10-09 |
ATE211821T1 (de) | 2002-01-15 |
EP0699300A1 (de) | 1996-03-06 |
EP0699300B1 (de) | 2002-01-09 |
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