CN103235186A - Method and system for measuring arc impedance by using spectrum - Google Patents

Abstract

The invention provides a method and a system for measuring arc impedance by using a spectrum. The method comprises the following steps: acquiring at least one part of a first image formed by an arc channel on a spectrograph through a lens assembly by using the spectrograph to obtain first spectral line length, wherein the first spectral line length is correlated with the size of the at least one part of the first image; comparing the first spectral line length with a reference spectral line length to calculate the diameter of at least one part of the arc channel; and calculating the impedance of the at least one part of the arc channel by using the calculated diameter and conductivity of the at least one part of the arc channel.

Description

Utilize the method and system of spectral measurement arc impedance

Technical field

The present invention relates to the measurement of arc impedance, relate more specifically to utilize the method and system of spectral measurement arc impedance.

Background technology

The measurement of the impedance of very fast transient overvoltage (VFTO) hf electric arc has great importance for timely discovery, measurement and the solution of electric system and network failure.

In the prior art, generally calculate VFTO hf electric arc arc resistance by measuring flame current and arc voltage, particularly, utilize the resistive component of arc voltage to obtain arc channel resistance divided by flame current, as shown in Equation (1) (referring to " M.J.Kushner.Arc resistance of laser-triggered spark gaps[J] .J.Appl.Phys.58,1744 (1985) "):

$R\left(t\right)=\frac{U\left(t\right)-[L_s\left(t\right)\frac{\mathrm{di}\left(t\right)}{\mathrm{dt}}+i\left(t\right)\frac{{\mathrm{dL}}_s\left(t\right)}{\mathrm{dt}}+L_e\frac{\mathrm{di}\left(t\right)}{\mathrm{dt}}]}{i\left(t\right)}---\left(1\right)$

Wherein, R (t) is hf electric arc resistance, and U (t) is measuring voltage, and i (t) is flame current, L _eBe the stray inductance of electric arc two end electrodes, L _s(t) the arc channel inductance for successively decreasing in time.

The fast-response capacitive divider is adopted in voltage measurement; Luo-coil is adopted in current measurement; The stray inductance of electric arc two end electrodes is estimated according to the electrode profile; The arc channel inductance calculates by channel radius, can arrange according to the loop and adopt different computation models, and common model has the coaxial transmission line model, as shown in Equation (2):

$L_s=l*\ln \left(\frac{{\mathrm{\ρ}}_2}{{\mathrm{\ρ}}_1}\right)*{10}^{-7}---\left(2\right)$

Wherein, ρ ₂Be the backflow radius, arranged by the loop and determine; ρ ₁Be channel radius, by measurements by laser interferometry, as shown in Figure 1, Fig. 1 shows the principle of method of the measurement arc channel radius of prior art.The cardinal principle of the measurements by laser interferometry channel radius shown in this figure is as follows.Utilize laser instrument to produce beam of laser and from side irradiation discharge channel, receive by receiving screen at opposite side, the image that obtains as shown in Figure 1, w wherein ₁Be channel diameter, w ₂Be the transition of plasma to the peripheral gas medium.

Yet there is following shortcoming in the method:

1) introducing of measurement mechanism can influence the Electric Field Distribution in experiment gap, thereby influences formation and the arc voltage of electric arc;

2) response time of voltage and current differs from and is difficult to determine, causes the result of calculation deviation to be difficult to control;

3) calculate aisle resistance and must measure channel radius, but in the prior art, the time arc channel radius measurement that the becomes method of taking by laser interferance method or framing camera measure, cost height and error are bigger;

4) to account for the ratio of arc voltage very little for the resistive component of the voltage of hf electric arc, deducts the computing method that perceptual component of voltage obtains resistive voltage by arc voltage and can introduce significant errors, and this belongs to the ill-conditioning problem in the computing method.

Therefore, need a kind of can high precision and measure the method and system of hf electric arc impedance at low cost.

Summary of the invention

The invention provides a kind of measuring method of non-intervention type, its spectrum by the measurement arc channel calculates the diameter of arc channel, thus the impedance of calculating arc channel.The method has overcome above-mentioned shortcoming of the prior art.

According to an aspect of the present invention, a kind of method of utilizing the spectral measurement arc impedance is provided, comprise: utilize at least a portion that spectrometer catches first image that arc channel scioptics assembly forms at spectrometer to obtain the first spectral line length, the described first spectral line length is associated with the size of described at least a portion of first image; By comparing the first spectral line length and reference spectrum line length with the diameter of at least a portion of calculating arc channel; And the conductivity of at least a portion of the diameter of at least a portion of the arc channel that calculates by utilization and arc channel, the impedance of calculating at least a portion of arc channel.

According to a further aspect in the invention, also provide a kind of system that utilizes the spectral measurement arc impedance, having comprised: lens subassembly, wherein arc channel forms first image by this lens subassembly; Spectrometer, its at least a portion that is used for catching described first image is to obtain the first spectral line length, and the wherein said first spectral line length is associated with the size of described at least a portion of first image; Computing unit, it receives the data about the described first spectral line length, by comparing the first spectral line length and reference spectrum line length with the diameter of at least a portion of calculating arc channel, and the conductivity of at least a portion of the diameter of at least a portion of the arc channel that calculates by utilization and arc channel, the impedance of calculating at least a portion of arc channel.

Further feature of the present invention will become clear by the following detailed description to one exemplary embodiment with reference to the accompanying drawings.

Description of drawings

In order at length to understand the present invention, the embodiment below describing by reference to the accompanying drawings now.Similar elements is represented with similar numeral in the accompanying drawing, wherein:

Fig. 1 shows the principle of method of the measurement arc channel radius of prior art;

Fig. 2 shows the block diagram of system of the impedance of measurement arc channel of the present invention;

Fig. 3 shows the circuit diagram of the signal processing circuit among Fig. 2;

Fig. 4 shows the input and output oscillogram of the signal processing circuit among Fig. 3; With

Fig. 5 shows the process flow diagram of method of the impedance of measurement arc channel of the present invention.

Embodiment

Below with reference to accompanying drawing the preferred embodiments of the present invention are described in more detail.Note, run through following description, set forth details and understand more completely of the present invention in order to provide.But the present invention can put into practice under the situation of these details not having.In other cases, do not illustrate or describe in detail known elements to avoid unnecessarily bluring the present invention.Therefore, it is illustrative that instructions and accompanying drawing should be considered to, rather than on the meaning of restriction.

Fig. 2 shows the block diagram of system of the impedance of measurement arc channel of the present invention.According to shown in Figure 2, electric current flows into two electrode of opposite 1, produces the hf electric arc passage between two electrodes 1.Light scioptics assembly 2 imagings on spectrometer that arc channel is sent.One side of the reception image input of spectrometer has image and catches window, it typically is the slit of thin-and-long, and its long side direction is parallel to the x axle among the figure.

Spectrometer can be caught the image that enters by slit to produce the spectrum picture.Comprise a series of spectral line in the spectrum picture.The information that spectral line reflects comprises the relative intensity of wavelength and respective wavelength, and intensity represents that with the brightness of spectral line wavelength and strength information can be used for calculating electron temperature and the electron density of arc channel.For same light source, the length of each bar spectral line is identical, and the length of spectral line is proportional to the size of images through slit.Because slit is longilineal, therefore, can think that the length of spectral line is proportional to image through slit in the axial length of x.Such spectrometer is commercially available, for example the 2300I type spectrometer of Princeton instrument company.But, should be appreciated that to the invention is not restricted to this concrete spectrometer type, as long as thereby can catch above-mentioned information and realize the present invention, the instrument of any other kind or the combination of instrument all should be embodiments of the invention, belong to scope of the present invention.

Under actual conditions, because discharge channel radially is being inhomogeneous, channel center's density is big, and peripheral density is little, thereby when slit was vertical with luminous object, channel boundary was the clearest, and the error that causes is little.Therefore, preferably, make arc channel scioptics assembly imaging perpendicular to the slit of spectrometer, take the discharge spectrum image, obtain the spectral line length of this moment, be designated as l ₁Notice that as shown in the figure, when slit was vertical with luminous object, the image that photographs by spectrograph slit was located width along the x direction corresponding to arc channel in axial certain part of y, namely arc channel is at the diameter of this position.

Obtain the information of reference light source then.At the reference light source of location arrangements one predetermined length of arc channel, for example length is the mercury lamp of 10mm.As mentioned above, because the length that take to see through the spectral line that the image of spectrograph slit obtains by spectrometer is proportional to the size of images through slit, and obtained electric arc above at certain part place along the axial width of x (namely, the diameter of arc channel), therefore for certain part by arc channel relatively along the spectral line length of the spectral line length of the axial image of x and the reference light source diameter with this part of acquisition arc channel, here make the length direction of reference light source along the x direction of principal axis, and it is imaged in the spectrograph slit, take its spectrum picture, spectral line length this moment l very ₂

Should be noted that mercury lamp herein only is example, can use other light sources, for example xenon lamp etc.The length of reference light source also can change according to concrete practice.

In addition, can be at every turn spectral line length of witness mark light source all.But can from storer, directly obtain length, spectral line length and the positional information etc. of the reference light source that has recorded.

As mentioned above, certain part by arc channel relatively is along the spectral line length of the spectral line length of the axial image of x and the reference light source diameter with this part of acquisition arc channel.When representing by formula, can provide certain a part of diameter d that following formula (3) calculates the hf electric arc passage:

$d=10*\frac{l_1}{l_2}\left(\mathrm{mm}\right)---\left(3\right)$

At last, calculate certain a part of impedance of arc channel by following formula:

$\frac{4}{\mathrm{\σ}\×\mathrm{\π}\×d^2}---\left(4\right)$

Wherein, σ is certain a part of conductivity of arc channel, and d is the diameter of this part of arc channel.

Alternatively, σ can obtain in the following manner.

At first, calculate electron temperature.Two spectral lines of the predetermined ion in the chosen spectrum picture, for example two of the monovalence fluorine ion spectral lines utilize the intensity rate method to calculate electron temperature T _e, can calculate electron temperature T by following formula _e:

$\frac{I_1}{{\mathrm{<figure-callout\; id="2"\; label="I"\; filenames="HDA00003100133000022.png"\; state="\{\{state\}\}">I</figure-callout>}}_2}=\frac{A_1{g}_1{\mathrm{\&lambda;}}_2}{A_2{\mathrm{<figure-callout\; id="2"\; label="g"\; filenames="HDA00003100133000022.png"\; state="\{\{state\}\}">g</figure-callout>}}_2{\mathrm{\&lambda;}}_1}*\exp (-\frac{E_1-{\mathrm{<figure-callout\; id="2"\; label="E"\; filenames="HDA00003100133000022.png"\; state="\{\{state\}\}">E</figure-callout>}}_2}{{\mathrm{kT}}_e})---\left(5\right)$

Wherein, k is Boltzmann constant, I ₁And I ₂Be respectively the radiation intensity of two predetermined spectral lines, A ₁And A ₂Be respectively the transition probability of two predetermined spectral lines, g ₁And g ₂Be respectively the statistical weight of two predetermined spectral lines, λ ₁And λ ₂Be respectively the radiation wavelength of two predetermined spectral lines, E ₁And E ₂It is respectively the excitation energy of two predetermined spectral lines.Can obtain electron temperature T according to following formula _eTo comprise different kinds of ions when it be known to those skilled in the art that arc discharge.Here choosing fluorine ion is to consider that the above-mentioned spectral line parameter of fluorine ion is acquisition and known easily in this area.Yet, as mentioned above, owing to may comprise different kinds of ions in the electrical discharge arc passage, so those skilled in the art can choose other ions that can measure and obtain and calculate electron temperature T _e

Calculate electron density n then _e, it is directly proportional with the spectral line halfwidth, is shown below:

n _e=C*Δλ （6）

Wherein, C is the Stark broadening factor, is constant; Can obtain electron density n according to following formula _e

For the spectral line halfwidth, preferably choose and calculate electron temperature T _eThe halfwidth of the spectral line of Shi Suoyong.Here, one that chooses in above-mentioned two spectral lines of monovalence fluorine ion is calculated halfwidth.

Calculate conductivity then.Here utilize the Spitzer correction formula to calculate conductivity, as follows:

${\mathrm{\&sigma;}}_0=1.53*{10}^{-2}*\frac{T^{3/2}}{\ln {(1+1.4*{{\mathrm{\&Lambda;}}_m}^2)}^{1/2}}---\left(7\right)$

Wherein,

Λ _m=1.24*10 ⁷*1.05*T ^3/2/n _e ^1/2 （8）

Notice that those skilled in the art can utilize multiple other method and formula to calculate conductivity, for example the Z﹠amp of Zollweg and Liebermann etc.; L model etc., referring to " the quadrate lope woods. the Primary Study of pulsed discharge plasma electromagnetic property [D]. the .2008.06 of Institutes Of Technology Of Nanjing ".

In addition, can all measure conductivity at every turn.But can from storer, directly obtain the conductivity information that has recorded.For example, under the identical situation of discharging condition, the conductivity parameter that obtains before can directly utilizing.

So far, utilize formula (4), can calculate certain a part of impedance of arc channel.

Owing to arc discharge can be decayed as time passes, in order to measure the channel impedance that arc discharge begins moment, can make the operation of spectrometer and arc discharge synchronous by synchronous triggering.Continue below to describe synchronous trigger method and corresponding device with reference to figure 1.

As shown in Figure 1, the synchronous triggering loop of spectrometer comprises: as B-dot coil, signal processing circuit and the shielded cable of sensor.

The B-dot coil is installed near the main discharge circuit, be in the same plane with discharge circuit, the magnetic field that electric current was uprushed and produced when the main discharge circuit discharging that is used for being coupled was initial can have time-delay ground substantially in the initial moment of main discharge circuital current and produce a voltage rising signals.In one embodiment, the B-dot coil can be the single turn air core coil, for example utilizes the enameled wire coiling to form, and its output terminal is connected to the input end of signal processing circuit by shielded cable.The B-dot coil is converted into electric signal output with the magnetic field of coupling.

Be connected to the input end of signal processing circuit by the shielded cable of a weak point from the electric signal of B-dot coil output, signal processing circuit is shaped as predetermined voltage with electric signal, 4V for example, square-wave signal, and be connected to spectrometer synchronous triggering signal input end by a shielded cable, be used for triggering spectrometer action.

Signal processing circuit as shown in Figure 3, it comprises for the voltage limiting module 31 of the voltage of the described electric signal of restriction and is used for electric signal is carried out shaping with the switch module 33 of output square-wave pulse signal.Voltage limiting module 31 comprises the diode D that is connected in series ₁With diode string D _sSwitch module can be various transistor well-known to those skilled in the art, MOSFET for example, and its control utmost point is connected diode D ₁With diode string D _sBetween node, the signal after the rectification is by its output stage (for example, source electrode) output.Signal processing circuit can also comprise filtration module 32 between voltage limiting module 31 and switch module 33, it carries out filtering and filtered signal is exported to switch module 33 described electric signal.This filtration module 32 can comprise resistor R ₁With capacitor C ₁Signal processing circuit can also comprise output load part 34, and it is connected to the output stage of switch module, is used for square-wave pulse signal is outputed to spectrometer with suitable voltage.The input signal of signal processing circuit and output signal are as shown in Figure 4.

As mentioned above, arc discharge can be decayed as time passes, and therefore, the channel impedance of each time point after arc discharge begins changes.The present invention can further measure arc discharge in the channel impedance at each time point place.Be described in detail below.

The signal of signal processing circuit output is input to after the spectrometer, can be with this signal delay regular hour t, catching of spectrometer moved t time delay.This time delay t is adjustable.For example, this time delay t can carry control software winspec32 by spectrometer and provide, and range of adjustment is 0 to infinitely great.By the method, spectrometer can obtain the spectrum picture of different discharge developing stage, obtains the arc channel impedance of different discharge regimes thus.

In addition, as shown in Figure 2, the arc channel between two electrodes is along the y direction of principal axis, and the image of spectrometer is caught slit and is parallel to the x axle.What therefore spectrometer once captured is that arc channel is along the diameter of the axial part of y.Because arc channel is not uniform along the axial diameter of y, thereby it also is inhomogeneous causing impedance, and therefore, the present invention has also considered this problem, the diameter of arc channel along the axial different piece of y of having gone forward side by side a pacing amount, thereby the impedance of calculating different piece.Be described in detail below.

Come the height of minute adjustment displacement platform by the micrometer caliper on the displacement platform of supporting spectrometer, thereby can regulate the height of spectrograph slit.Repeat the step of above measurements and calculations then, to measure arc channel along the impedance at the axial diverse location of y place.

For example, utilize said method, utilize formula (7), by repeatedly measuring a plurality of Conductivity Calculation values.Utilize approximating method known in the art then, for example Lorentz match obtains arc channel along the axial conductivity of y (y).This match can realize with different computational tools, for example the product of OriginLab company " Origin8.6 ", perhaps Matlab etc.

Conductivity (y) be multiply by channel cross-sectional area get inverse in arc channel length direction upper integral, can obtain the impedance of at least a portion of corresponding hf electric arc passage constantly, as follows:

$r=\underset{y-}{\overset{y+}{\&Integral;}}\frac{4}{\mathrm{\&sigma;}\left(y\right)\&times;\mathrm{\&pi;}\&times;{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="HDA00003100133000022.png"\; state="\{\{state\}\}">d</figure-callout>}}^2}*\mathrm{dy}---\left(9\right)$

According to this equation, when y gets different values, can obtain the impedance of the different piece of arc channel.

The method of utilizing the spectral measurement arc impedance is according to an embodiment of the invention described below in conjunction with Fig. 5.Fig. 5 shows the process flow diagram of this method.

This method starts from 500.

510, utilize spectrometer to catch at least a portion of first image that arc channel scioptics assembly forms at spectrometer to obtain the first spectral line length.

520, by comparing the first spectral line length and reference spectrum line length with the diameter of at least a portion of calculating arc channel.Here the reference spectrum line length can also can utilize spectrometer measurement spectrum to obtain by reference light source being placed on the position of arc channel by directly obtaining from storer.

530, the conductivity of the diameter of at least a portion of the arc channel that calculates by utilization and at least a portion of arc channel, the impedance of calculating at least a portion of arc channel.

This method ends at step 540.

In addition, in further alternative embodiment, in order to measure arc discharge the impedance of moment taking place, can utilize the sensor sensing to cause the initial current signal of electric arc, with the operation of triggering spectrometer, thereby makes spectrometer synchronously measure arc channel.

In addition, in further alternative embodiment, for measure arc discharge take place after, the impedance of random time point before electric arc is withered away, can after with the initial current signal delay schedule time, trigger the operation of spectrometer, with the diameter of at least a portion of the arc channel that obtains the different time points place at least.

In addition, in further alternative embodiment, for the diverse location place of measuring arc channel and the impedance of different piece, can be along position that the direction that is parallel to arc channel is adjusted spectrometer with the diameter at the diverse location place that obtains arc channel at least, thereby the impedance of part of calculating the different length of arc channel.

As mentioned above, the invention provides a kind of measuring method of non-intervention type, calculate the diameter of arc channel by the arc channel emission spectrum, and utilize conductivity to calculate the impedance of arc channel.The present invention utilizes optical method for measuring to obtain reflecting the parameter of microscopic particle motion state, thereby calculates channel impedance, the problem that does not exist voltage, current measurement to introduce.And utilize the light source of known dimensions and discharge channel imaging higher to the way precision that recently obtains channel diameter, and cost is not high.Utilize technical scheme provided by the present invention, can also measure arc channel in the impedance of the specific part of the impedance of each discharge regime and/or arc channel, this provides the practicality of greater flexibility and Geng Gao for the arc channel impedance measurement.

Claims (20)

1. method of utilizing the spectral measurement arc impedance comprises:

Utilize at least a portion that spectrometer catches first image that arc channel scioptics assembly forms at spectrometer to obtain the first spectral line length, the described first spectral line length is associated with the size of described at least a portion of first image;

By comparing the first spectral line length and reference spectrum line length with the diameter of at least a portion of calculating arc channel; And

The conductivity of the diameter of at least a portion of the arc channel that calculates by utilization and at least a portion of arc channel, the impedance of calculating at least a portion of arc channel.

2. the method for claim 1, wherein said first image is caught the long side direction of window perpendicular to the image on the spectrometer.

3. the method for claim 1, wherein said reference spectrum line length obtains at second image that spectrometer forms by utilizing spectrometer to catch reference light source scioptics assembly, and wherein the image that is positioned on the spectrometer of second image is caught window.

4. the method for claim 1 also comprises:

The position of adjusting spectrometer along the direction that is parallel to arc channel is with the diameter at the diverse location place that obtains arc channel at least.

5. the method for claim 1 also comprises:

Utilization causes that the initial current signal of described electric arc triggers the operation of spectrometer.

6. as claim 4 or 5 described methods, also comprise:

After with the initial current signal delay schedule time, trigger the operation of spectrometer, with the diameter of at least a portion of the arc channel that obtains the different time points place at least.

7. the method for claim 1, the impedance of wherein calculating at least a portion of arc channel by following formula:

$\frac{4}{\mathrm{\&sigma;}\&times;\mathrm{\&pi;}\&times;d^2}$

Wherein, σ is the conductivity of at least a portion of arc channel, and d is the diameter of at least a portion of arc channel.

8. method as claimed in claim 7, wherein calculate the conductivity of at least a portion of arc channel by following formula:

$\mathrm{\&sigma;}=1.53*{10}^{-2}*\frac{T^{3/2}}{\ln {(1+1.4*{{\mathrm{\&Lambda;}}_m}^2)}^{1/2}}$

Λ wherein _m=1.24*107*1.05*T ^3/2/ n _e ^1/2, T is the electron temperature of arc channel, n _eElectron density for arc channel.

9. method as claimed in claim 8 is wherein passed through to use two predetermined spectral lines being scheduled to ion, utilizes following formula to calculate electron temperature T:

$\frac{I_1}{I_2}=\frac{A_1{g}_1{\mathrm{\&lambda;}}_2}{A_2{g}_2{\mathrm{\&lambda;}}_1}*\exp (-\frac{E_1-E_2}{\mathrm{kT}})$

Wherein, k is Boltzmann constant, I ₁And I ₂Be respectively the radiation intensity of two predetermined spectral lines, A ₁And A ₂Be respectively the transition probability of two predetermined spectral lines, g ₁And g ₂Be respectively the statistical weight of two predetermined spectral lines, λ ₁And λ ₂Be respectively the radiation wavelength of two predetermined spectral lines, E ₁And E ₂Be respectively the excitation energy of two predetermined spectral lines, and

Calculate the electron density n of arc channel by following formula _e:

n _e=C*Δλ

Wherein C is the stark broadening factor, and Δ λ is the spectral line halfwidth.

10. method as claimed in claim 8 or 9 also comprises:

Obtain the conductivity of arc channel along the function (σ (y)) of the direction of arc channel by the Lorentz approximating method; And

Calculate the impedance of at least a portion of arc channel by following formula:

$r=\underset{y-}{\overset{y+}{\&Integral;}}\frac{4}{\mathrm{\&sigma;}\left(y\right)\&times;\mathrm{\&pi;}\&times;d^2}*\mathrm{dy}.$

11. a system that utilizes the spectral measurement arc impedance comprises:

Lens subassembly, wherein arc channel forms first image by this lens subassembly;

Spectrometer, its at least a portion that is used for catching described first image is to obtain the first spectral line length, and the wherein said first spectral line length is associated with the size of described at least a portion of first image;

Computing unit, it receives the data about the described first spectral line length, by comparing the first spectral line length and reference spectrum line length with the diameter of at least a portion of calculating arc channel, and the conductivity of at least a portion of the diameter of at least a portion of the arc channel that calculates by utilization and arc channel, the impedance of calculating at least a portion of arc channel.

12. system as claimed in claim 11, wherein said first image is caught the long side direction of window perpendicular to the image on the spectrometer.

13. system as claimed in claim 11 also comprises:

Reference light source,

Wherein by utilizing spectrometer to catch second image that reference light source scioptics assembly forms at spectrometer to obtain described reference spectrum line length, wherein the image that is positioned on the spectrometer of second image is caught window.

14. system as claimed in claim 11 also comprises:

The spectrometer position regulator, it adjusts the position of spectrometer along the direction that is parallel to arc channel, thereby obtains the diameter at the diverse location place of arc channel.

15. system as claimed in claim 11 also comprises:

Sensor, it is used for the initial current signal that sensing causes described electric arc; And

Signal processing circuit, it is for the treatment of the current signal of institute's sensing and output to spectrometer, thereby triggers the operation of spectrometer.

16. system as claimed in claim 15, wherein said signal processing circuit comprises:

The voltage limiting module, it limits the voltage of described current signal;

Filtration module, it carries out filtering to described current signal;

Switch module, it carries out shaping to described filtered current signal; With

Output unit, the signal behind its output Shaping.

17. as claim 14 or 15 described systems, also comprise:

The time delay unit, it is connected between described signal processing unit and the described spectrometer, is used for triggering with the initial current signal delay schedule time after the operation of spectrometer, with the diameter of at least a portion of the arc channel at acquisition different time points place.

18. system as claimed in claim 11, wherein computing unit calculates the impedance of at least a portion of arc channel by following formula:

$\frac{4}{\mathrm{\&sigma;}\&times;\mathrm{\&pi;}\&times;d^2}$

Wherein, σ is the conductivity of at least a portion of arc channel, and d is the diameter of at least a portion of arc channel.

19. system as claimed in claim 18, wherein computing unit calculates the conductivity of at least a portion of arc channel by following formula:

$\mathrm{\&sigma;}=1.53*{10}^{-2}*\frac{T^{3/2}}{\ln {(1+1.4*{{\mathrm{\&Lambda;}}_m}^2)}^{1/2}}$

Λ wherein _m=1.24*10 ⁷* 1.05*T ^3/2/ n _e ^1/2, T is the electron temperature of arc channel, n _eBe the electron density of arc channel,

Wherein by using two predetermined spectral lines of predetermined ion, utilize following formula to calculate electron temperature T:

$\frac{I_1}{I_2}=\frac{A_1{g}_1{\mathrm{\&lambda;}}_2}{A_2{g}_2{\mathrm{\&lambda;}}_1}*\exp (-\frac{E_1-E_2}{\mathrm{kT}})$

Wherein, k is Boltzmann constant, I ₁And I ₂Be respectively the radiation intensity of two predetermined spectral lines, A ₁And A ₂Be respectively the transition probability of two predetermined spectral lines, g ₁And g ₂Be respectively the statistical weight of two predetermined spectral lines, λ ₁And λ ₂Be respectively the radiation wavelength of two predetermined spectral lines, E ₁And E ₂Be respectively the excitation energy of two predetermined spectral lines, and

Calculate the electron density n of arc channel by following formula _e:

n _e=C*Δλ

Wherein C is the stark broadening factor, and Δ λ is the spectral line halfwidth.

20. system as claimed in claim 19, wherein computing unit obtains the conductivity of arc channel along the function (σ (y)) of the direction of arc channel by the Lorentz approximating method, and the impedance of calculating at least a portion of arc channel by following formula:

$r=\underset{y-}{\overset{y+}{\&Integral;}}\frac{4}{\mathrm{\&sigma;}\left(y\right)\&times;\mathrm{\&pi;}\&times;d^2}*\mathrm{dy}.$

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