Solder the new progress of diagnostic technology of electric arc laser

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Summary: Thomson scattering method is the diagnostic method that uses gas of affirmatory electric arc and electronic temperature and electronic density extensively. Thomson scattering is the vibration that passes free electron the process in energy of field of electromagnetism of aleatoric direction radiate, free electron is oscillatory below action of incident wave electric field, and with occasionally extremely radiant form radiate gives a share incident energy. This kind of method has the advantage that can measure local temperature, and its accuracy is not premise with the existence of local thermodynamic balance. This method can be measured effectively solder electric arc is radial locally temperature; Pass the spectral line analysis of the electronic feature of Thomson scattering, still can decide electronic temperature and electronic density distributing directly. The article introduced in recent years abroad is mixed in this domain gas the new progress that electronic temperature and electronic density measure. Discussed the prospect that this technology develops in home. Keyword: Thomson scattering; Laser is diagnosed; Solder electric arc; Spectral line analyses the progress that the preface produces as industry, to get used to the processing technique requirement that raises ceaselessly, welder author also is being improved ceaselessly and perfect solder equipment and craft. The join that electric arc regards heat source as to apply at material already had history of more than 100 years. Arrive from World War II on the 60 time metaphase of the century, include laser, electron beam inside much is commonly used solder the method already came out, also aroused people to be opposite at the same time the exploration of its mechanism and understanding. Below this one setting, accelerate research to solder electric arc condition, with theory of electric arc physics guidance solders craft, raise manufacturing efficiency and product quality to having great real sense. Also developed a variety of soldering so electric arc diagnoses a method. 1 different electric arc diagnoses a method before, in the method that enrages body temperature, electron temperature and electronic density in affirmatory plasma, shooting spectral way is the most commonly used diagnostic method. However, authorities ministry is only thermodynamic evenly (LTE, local Thermodynamic Equilibrium) when existing in electric arc plasma, measure an outcome ability is effective. Think commonly, when the electron counts density to exceed 1023m-3, with respect to OK and contented LTE[1] , that is to say, those electronic density exceed the area of 1023m-3 to be able to measure the temperature that gets electric arc. However, the existence of the LTE in free combustion electric arc is open to question. In the meantime, traditional emissive spectrum method is intensity of pair of the radiate on observation direction accumulate, it cannot is opposite directly the bit more individual condition parameter in electric arc does visit a patient at home to break. The effect that consequently its measure electric arc temperature directly is not quite ideal also. Decide these parameter in plasma directly, it is especially when noninterference ambient conditions, the spectral line appearance that a kind of feasible method is scattering of plasma laser Thomson analyses a way [2] . Snyder and Bentley were measured through this method often press next free flaming dc arc, the curve of temperature of central line gas that the description gives to change along with time [3] ; Deviate of distributinging large-scale of the radial that Bentley applies this method to discover temperature of the electron in often pressing arc of free combustion argon and electronic density and axial LTE[4] . Below condition of arc of free combustion argon, the temperature that magic art of music of consumed of different learned man and other method measure is put in very big difference between the value. citing, koyabashi and Suga[5] , Hsu, Etemadi and magic art of Pfender[6] consumed music measure discovery these electric arc have the temperature peak value that exceeds 20000K. Contrary is, seeger and magic art of Tiller[7] consumed music are measured, and Gick, Quigley and Richards[8] are measured with electrostatic bougie method, below condition of same kind electric arc, they get the highest temperature of electric arc is 12000K about. And the person such as Murphy uses laser scattering method in same kind electric arc, cathode can be stood by in proof electric arc around temperature is as high as 20000K, electric arc radial is measured below the condition that can exist in LTE of Lai Yu notting comply locally neuter atom and ionic temperature [9] , the parameter that is plasma measures open up a new approach. Scattering of Thomson of principle of 2 Thomson scattering is the stretch scattering that happens between photon and free electron, it is quanta actually mechanical medium Compton scattering, just happen in feebleminded area (H ω <<mec2) . Below low scattering condition, use classical electrodynamics to be able to describe this one process very well. Its are classical image shows 1 times like the graph: When a bundle illuminate of planar electromagnetic wave arrives on a free electron when, the electron is oscillatory below the action of electromagnetic wave, do not be as a result of the acceleration of oscillatory electron 0, because of this electron meeting radiate gives electromagnetic wave, and with occasionally extremely radiant form radiate gives one fraction draws incident energy, process of this kind of radiate is Thomson scattering. Make the same score face electromagnetic wave when a bundle incident when going up to a flock of electrons in plasma, at this moment the overlay of be concerned with that scattering electromagnetic wave is wave of scattering of each motion free electron. Because the spectrum of this scattering light and plasma are medium,athletic condition of the electron has very big concern. Be based on this reason just about, thomson scattering makes the strong instrument of the collective motion in the condition parameter of diagnostic plasma and plasma. Thomson scattering method has the advantage that can measure local temperature, and the existence that its accuracy does not rely on LTE. Current, abroad's already successful applied Thomson scattering will measure parameter of microcosmic particle physics, carry the transmission of laser light beam, complementary with certain telescope, collect the spectrum that mirrors parameter of physics of microcosmic particle model or other signal, give place to need physical parameter through building imitate to add up to computation. The research of 3 Thomson scattering makes progress 3.

1Thomson scattering measures the application that go up to be in the method of affirmatory plasma gas and electronic temperature and electronic density in temperature, what often apply of late is method of laser Thomson scattering. From the spectrum of laser scattering light the temperature that place obtains to beg in distributinging is worth, implementation measures the kinetic temperature that particle weighs in plasma, electron temperature and electronic density to diagnose. Now, this kind of technology has expanded a variety of laser, include aeriform laser, solid laser, semiconductor laser to wait. When electronic density exceeds 1022m-3, scattering smooth spectral line distributings by the ion with central narrow place and circumjacent area is wide and symmetrical electron distributings composition. Analyse these spectral line, with respect to temperature of attainable heavy particle, electron temperature and electronic density. The heterodyne demodulation that carries Thomson scattering laser [10] , acquire ionic composition spectral line, the successful already move arc temperature that uses affirmatory low pressure, big electricity. With harmonious tape wide dye laser regards laser as the source, undertake spectral analysis with monochromator, the temperature of spectral line gas in can obtaining move arc [11] . The person such as Snyder discovers the accretion as electric current of solder fire work, after aeriform temperature rises to some to stabilize a value ceaselessly, keep changeless [12] . Document [4, 13, 14] covers to often press electron of plasma issueing heat and ionic Thomson scattering to measure an outcome respectively, point out the spectral line that often presses next passing to stimulate smooth Thomson scattering analyses a method to measure Ar plasma efflux and the electronic temperature that transfer arc, electronic temperature peak value is as high as 20000K left and right sides; Heavy particle temperature is 12000K left and right sides, 14000K left and right sides respectively in plasma efflux and move arc. Measure gotten corresponding temperature to magic art of music of score analyse consumed, by the watch 1 in can see, spectral when microtherm method crossed overmeasure to calculate temperature to be worth apparently. This produces the deviate at LTE, and this kind of deviate is by plasma the blasts off from radiate of central area linear atom of exterior area is aroused bring about. And when temperature prep above is worth certainly, the temperature value that spectral method and laser scattering method measure keeps consistent [6, 7] . These results show means of spectral below certain condition law cannot provide reliable electronic temperature to measure an outcome. Normal Align=center> expresses 1 different diagnostic method to measure temperature to be worth is relevant compare Normal Align=center> transfers arc temperature (K) Normal Align=center> plasma (K) Normal TEXT-ALIGN of temperature of Center" Align=center> electron: Center" Align=center> (K) Normal TEXT-ALIGN of Center" Align=center> ionic temperature: Center" Align=center> (K) Normal Align=center> suffers stimulate temperature Normal Align=center> (K) Normal TEXT-ALIGN of Center" Align=center> spectral law: Normal Align=center>16000[4] : ① Normal TEXT-ALIGN of law of Center" Align=center>Thomson scattering: Normal Align=center>14000[14] : Normal Align=center>12000[14] : Normal Align=center>20900 ± : Normal Align=center>22000 ± : Normal Align=center>14200 ± : Normal Align=center>12600 ± : ② of Center" Align=center>14500 [12] notes: What ① represents is to often approach next 100A freedom the each temperature value that place of the 2mm below the cathode of combustion Ar arc measures; Normal > ② represents is the Ar that often presses next 900A the each temperature value that place of 2mm of ahead of fire of plasma efflux solder measures. Snyder, Lassahn and Reynolds[14] burn in 100A freedom place of the 2mm below the cathode of Ar arc is measured so that electronic temperature is 20900 ± 1700K, ionic temperature to be 14200 ± 700K. Bentley[4] repeated electronic temperature to measure, what he uses is Thomson scattering spectrum analytic measurement technique, obtain the electronic temperature of 20400 ± 500K from inside the spectrum of scattering light, confirmed to the phenomenon that cannot satisfy LTE can appear in often pressing arc issueing argon; In the meantime, electronic temperature wants tall 4000K than ionic temperature at least. And consumed music magic art measures same electric arc, reach suffer stimulate temperature to be 16600K. The electron that Tanaka and Ushio[15] compared Thomson scattering to measure in the Ar arc of 50A and 100A, ionic temperature is worth what measure with spectral law to suffer stimulate temperature worth. They discover ionic temperature is mixed suffer stimulate temperature to differ not quite, and electronic temperature wants tower above to make an appointment with 5000K. Undertake metrical in often pressing next plasma efflux, as much can observation arrives electronic temperature is far mix than ionic temperature suffer stimulate temperature tall. Watch 1 gave out likewise the comparison between each temperature that the place of 2mm of ahead of fire of solder of Ar plasma efflux of corresponding 900A measures. Can conclude from inside these results, electronic temperature is mixed than ionic temperature suffer stimulate temperature to want thousands of tall Er article. 3.

2The analysis that Thomson scattering temperature measures 3.

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The bigger difference between the deviate electron temperature of the LTE in plasma of 1 electric arc and ionic temperature makes clear, be identical always is not between these experimental results and the academic research that heat up plasma. In academic research, think to often press next soldering normally the central area of electric arc and plasma efflux is to be in LTE to fall. The translation energy that LTE asks belongings is qualitative distributings accord with Maxwell-Boltzmann to distributing; The temperature of all material that ask to be in these distributinging to fall is same. Academic research and experimental result make clear, to 1023m-3 of electronic density prep above, the area of deviate electrode and brim is be in or receive those who be bordering on LTE, because collision of the high speed in electric arc and plasma efflux brought about the fast balance of states of matter,this is. However, a lot of scholars proved the LTE of deviate of a few area in hot plasma. citing, inside 1mm of ahead of cathode of free combustion electric arc excitation state atomicity is measured very few [16] ; This basically is the fast convection decision of the cold air that brings about by contractive action. The deviate that standing by zincous place to also can produce LTE [17] . In plasma brim area, because radiant resonance is absorbed, amount of excitation state atom is very much; And, gradient brought about bigger chroma to diffuse, this kind diffuses to be gotten more quickly than a few complex reaction much, bring about local chemistry to balance the deviate of composition then. LTE can be used at models of all hot plasma computation almost suppose, it can simplify the computation of feature of plasma of industrial electric arc. Measure in electric arc in, assume LTE comes as much basic atomicity occupies derivation. Be based on these reasons, measure electronic temperature through Thomson scattering, come the effectiveness of LTE of test and verify is very useful. As above, began temperature to survey a test in a lot of labs. 3.

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2 numeric computation analyse relative to nuclear fusion speech, scattering of the Thomson in plasma is the measurement technique of the most reliable electron temperature. However, the very high electron density in hot plasma and very low electronic temperature specification are existing to stimulate ray radiation in these plasma to the electron heat apparently action. In all research that afore-mentioned mentioning, the electronic temperature that regards laser pulse energy as function through measuring, and go to extrapolate of result curve linear 0 pulse energy, considered this kind to heat action. Murphy[18] points out put in a lot of problems in these extrapolate computation, right in the paper of these results spread out undertake discussion, these problems when thinking to temperature is measured in the plasma that changes in temperature are inherent, and return an explanation to say palpability uses spread bundle the difficulty when stimulating beam of light to undertake metrical. In these measurement, because stimulate the low energy density of beam of light, of the electron heat action is greatly abate. 3.

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The analysis that 3 temperature measure influencing factor is a few otherer the scholar gave out the different explanation with unusually high temperature of the electron when Thomson scattering is measured. The person such as Gregori [19] was done a few measure, the electronic temperature that the result makes clear to computation reachs depends on apparently scattering angle (incident stimulate beam of light and measure the included angle between the axis) . Because be put in bigger chroma gradient,be in inside scattering limits, scattering angle can increase to the decision level of electronic temperature, at the same time gradient of this kind of chroma makes electronic temperature unusually high, the electronic temperature on plasma efflux axes has 10500K. However, the person such as Snyder, Crawford and Fincke [the collision that 20] distributings electron of ascribe of orientaton of this kind of angle spreads out, latter is right the impact of the electronic temperature that in measuring, obtains is very little. Spread out considering this kind, electronic temperature is 18000K about, ambitious still the temperature that stimulates atom and ion at sufferring. The person such as Terasaki [21] thinks the electron in helium arc distributings not to depend on scattering angle, to helium arc, the effect that collision develops is very apparent, the person such as this and Snyder, Crawford and Fincke [the result of 20] is consistent. Thomson scattering is used to survey the case of temperature of electric arc electron and electronic density outside the country giving out here, in order to offer reference. 1994, the person such as Snyder [the spectral line analysis of the electronic feature that 13] passes laser Thomson scattering, often press Ar arc certainly directly the electronic temperature of plasma and electronic density distributing. With Miller SG-100 plasma solder fire produces the plasma efflux of a research in the experiment. Throughput is 35.

4L/min. Uses laser source is tone Q Nd:Y of times frequency pulseAG laser, undertake metrical when wavelengh is 532nm. Will decide the spectrum of laser scattering with monochromator, accuse 2 dimension to enhance CCD resembling element with the door (ICCD) diode array detector will detect spectral line. The door of detector accuses through putting through the Q switch of laser sparks, the door is wide for 25ns. To reduce interference, with 1.

The lenticular focusing of 5m focal length is incident stimulate beam of light. Data is gotten when laser energy changes by limits of pulse of 50 ～ 225mJ/ . Mix with half plane Bruce is special horny polarization appearance will adjust laser energy. To obtain the strongest signal, will rotate with another half wave plane the polarization of incident laser direction, those who make is as parallel as monochromator entrance slit. The achromatic lens that uses 300mm of two diameters 40mm, focal length will collect scattering light and deliver it to monochromator. Will restrain free polarization with Glan-Thompson polarization appearance plasma setting radiate, upend direction polarization conveys in the meantime scattering is smooth. Solder fire is in upend position, scattering angle is 90º , it is plasma axes and incident laser bundle the included angle between. Graph 2 gave out the device diagram that scattering experiments. Normal > is mixed in graph 3 (a) respectively graph 3 (B) in gave out typical electron feature distributings, they are to be in Z=2mm of position of R=0mm of position of radial of solder fire ahead, axial and Z=20mm place to be measured. Below two kinds of circumstances, solder fire electric current is 900A. Cumulative inside 50 laser pulse these spectral line, compare in order to raise letter a confusion of voices (SNR, signal-to-noise Ratio) . The strong wave crest that 0 GHz is in is the ionic feature of impartible differentiate. Have these data nonlinear least square plans to close, and eliminate ion feature, get smooth spectral line so. The symmetry of spectral line shows those who distributing to electronic rate distributinging function is obedient Maxwell. Of function of reaction of buy of spectral line traditional Chinese clothes roll accumulate an influence very small, can cause electronic temperature and density to plan to add up to a value to be less than the change of 2% only. Normal > passes the electronic feature that analyses laser Thomson scattering, obtained often press Ar arc the electronic temperature of plasma efflux and electronic density distributing. These measure a result to make clear, in whole plasma apparent deviate LTE. Plane is exported to go up in solder fire, temperature of measures central line electron exceeded 20000K, and the aeriform temperature of same position is 12500K. And, as the accretion that axial is apart from, electronic temperature keeps changeless, and electronic density drops apparently. To discuss the concern of electronic temperature and density and scattering angle, 2000, the person such as Snyder [the laser wavelengh that 20] chooses 532nm and 355nm respectively, alexandrine place narrates experimental device, in often pressing Ar plasma efflux, the spectral line that the electron that passes laser Thomson scattering distributings is analysed, obtain electronic temperature and density then. Experimental result shows their effort is correct. Normal > data all are in place of 5mm of axial of ahead of 0mm of ＝ of R of plasma efflux radial, ejective face to obtain. Argon air velocity of flow is 35.

4L/min, solder fire electric current is 900A. Graph 4 gave out respectively the electronic temperature of corresponding wavelengh 532nm, 355nm and electronic density graph. Can see from inside the graph, when wavelengh is 532nm, be in as scattering angle 0 ～ 80ºReduce ceaselessly inside limits, electronic temperature rises apparently, electronic density number basically has nothing to do with scattering angle; And to wavelengh 355nm character, electronic temperature or electronic density did not follow the change of scattering angle apparently and change. This shows, when laser wavelengh is 532nm, scattering angle is having decision effect apparently to electronic temperature; When scattering angle is less than 80º , follow angle reduce electronic temperature to rise. Because be when small scattering angle,this is, the stretch collision rate of electronic plasma wave is older than Landor collision rate. This makes the electronic plasma wave that the electron distributings produces resonance construction spread out. Reduce and rise what this spread out to bring about electronic temperature to follow scattering angle then. However, when wavelengh is 355nm, to all scattering angle, orchid line collision rate wants than stretch collision rate big. Accordingly, the stretch collision that can think when this one wavelengh the electron distributings is but of oversight; Electronic temperature value and scattering angle have nothing to do. The person such as Snyder also confirmed this one phenomenon in the experiment. In the meantime, corresponding wavelengh 532nm and 355nm part when passing smaller scattering angle measure data, the ration of the stretch collision effect that can reach the electron distributings is worth. Normal >5 foreground and look into Normal >Thomson scattering can measure local temperature as a result of its and the advantage that accuracy does not depend on LTE to exist, and the feature that has optical probe, already wider and wider application burns at measuring freedom electric arc and the aeriform temperature that heat up plasma, electron temperature and electronic density, scored greater success in theory and industrial application. In home, measure and diagnose solder electric arc still basically is electric arc telecommunication date detects method, high speed photographs / the method such as law of spectral like law of light intensity of law, electric arc, electric arc law, signal of electric arc sound and X ray law. And in application laser scattering measures electric arc the research of the respect such as parameter of microcosmic particle hot physics is returned at present in start level. The electric arc that needs a convention in research diagnoses method and union of laser scattering measurement technique to rise, use Thomson laser scattering to diagnose a method, build have tall when, the is based on effect of pulse laser scattering spectral diagnostic system of empty resolution, use testing instrument of advanced electric arc signal, receive the scattering signal of laser and action of electric arc photograph, carry number - modular changeover and numeric computation, solder in order to obtain the information such as density of the electronic temperature of electric arc, electron, implementation solders below position of hot to be not balance the accurate observation of each physics parameter mixes electric arc analysis, directive welder art. Normal > as telescope, detect of equipment increasingly masterly, detect as laser scattering of academic research of the technology and practice application deepen ceaselessly, home solders bound of electric arc physics also is sure to turn over a new one page that diagnose and knows electric arc. CNC Milling CNC Machining