CN103941166B - High-temperature gas breakdown characteristics detecting device and method under a kind of VFTO - Google Patents

Abstract

High-temperature gas breakdown characteristics detecting device and method under a kind of VFTO, this device realizes the detection of gas breakdown process when VFTO, including gas confinement chamber, heating unit, discharge cell, spectrogrph, temperature measurer, gas charge and discharge and recovery unit, voltage source, VFTO generation unit, ammeter and computer；The method is from the breakdown process of the angle detected gas of microcosmic, by the light intensity in spectrometer measurement breakdown process and wavelength, obtains the particle temperature in breakdown process, and obtains the viscosity of particle, electrical conductivity, diffusion coefficient further；And according to the feature of particle encounter under VFTO, the collision term of Boltzmann equation is corrected.

Description

High-temperature gas breakdown characteristics detecting device and method under a kind of VFTO

Technical field

The invention belongs to field of gas discharge, be specifically related to a kind of high-temperature gas breakdown characteristics detecting device and method under VFTO.

Background technology

Gas, liquid and solid dielectric breakdown characteristics under the normal condition such as direct current, industrial frequency AC has been carried out considerable research work, in recent years, the dielectric insulation performance under extreme condition and multi-form and condition gas discharge rule etc. cause domestic and international extensive concern.At super extra-high voltage GIS (GasInsulatedSwitchgear, fully closed combined electric unit), due to frequency height of restriking during isolator operation, VFTO (the VeryFastTransientOver-voltages of tens MHZ can be produced, fast transient overvoltage), the break performance of harm switch.Therefore, when for VFTO, the research of gas breakdown process is significant, but, the detection means of gas breakdown characteristics also imperfection when at present for VFTO.When VFTO, the state often right and wrong of gas breakdown process plasma are from equilibrium state, it is considered as interparticle collision process, need to describe with Non-Boltzmann distrubution function, and the very high frequency due to VFTO, in breakdown process, interparticle collision there are differences with interparticle collision under power-frequency voltage, and original Boltzmann collision model cannot be suitable for this extreme case.

Summary of the invention

For the deficiency that prior art exists, the invention provides a kind of high-temperature gas breakdown characteristics detecting device and method under VFTO.

Technical scheme:

High-temperature gas breakdown characteristics detecting device under a kind of VFTO, including:

Gas confinement chamber, heating unit, discharge cell, spectrogrph, temperature measurer, gas charge and discharge and recovery unit, voltage source, VFTO generation unit, ammeter and computer；

Described gas confinement chamber is the cylinder barrel shaped structure closed, and adopts adiabatic transparent material, for filling gas；

Described heating unit includes resistance wire and potsherd；Described resistance wire is arranged on gas confinement chamber intracavity bottom position；Described potsherd is laid on resistance wire surface；

Described discharge cell includes anode electrode plate and cathode electrode plate；Described anode electrode plate and cathode electrode plate are separately mounted on the centre position of gas confinement chamber internal chamber wall, and anode electrode plate and cathode electrode plate staggered relatively；

The probe of described spectrogrph is inserted in gas confinement chamber inner chamber and is placed between anode electrode plate and cathode electrode plate, and the outfan of spectrogrph connects an input of computer；

Described temperature measurer is arranged on gas confinement chamber inner cavity top position；

Described gas charge and discharge passes through trachea and gas confinement chamber inner space with recovery unit；

Two outfans of described voltage source connect two terminals of resistance wire respectively；

Described VFTO generation unit includes pulse trigger group, pulse generator group and VFTO combiner circuit；Described pulse trigger group includes multiple pulse trigger；Described pulse generator group includes multiple pulse generator；The input of each pulse trigger in described pulse trigger group outfans different from described computer respectively connect；The outfan of each pulse trigger in described pulse trigger group is connected with the input of each pulse generator in pulse generator group respectively；The outfan of each pulse generator in described pulse generator group connects each input of VFTO combiner circuit respectively, and the outfan of VFTO combiner circuit is connected by the link of ammeter with anode electrode plate and gas confinement chamber as the outfan of VFTO generation unit；The zero potential end of described VFTO generation unit is connected with the link of cathode electrode plate and gas confinement chamber；

Described resistance wire is for being heated the gas in gas confinement chamber；Described potsherd is for isolating between metallic vapour and the tested gas of generation during to Resistant heating；

Spacing scalable between anode electrode plate and the cathode electrode plate of described discharge cell；

Described spectrogrph is used for measuring the intensity of spectrum of gaseous plasma generation and the wavelength of spectrum and the intensity of the spectrum recorded and the wavelength of spectrum being sent to computer；

Described voltage source, for powering for resistance wire, makes resistance wire generate heat；Described temperature measurer is for measuring the temperature of heated gas；

Described gas charge and discharge and recovery unit are used for inflation and the evacuation process of gas confinement chamber；

The distribution of various particles and calculate the diffusion coefficient of particle according to the distribution function of particles various in gas breakdown process respectively in the intensity of spectrum that the gaseous plasma that described computer sends for receiving spectrogrph produces and the wavelength of spectrum the various particle temperatures calculating in plasma and gas breakdown process, the electrical conductivity of particle and the coefficient of viscosity of particle, and be used for emulating acquisition VFTO, and each pulse trigger in the VFTO of acquisition being decomposed into the nanosecond pulse signal of multiple different cycles and being sent respectively to the pulse trigger group of VFTO generation unit；

Each pulse trigger in described pulse trigger group is for controlling the output frequency of each pulse generator in pulse generator group respectively；Each pulse generator in described pulse generator group is for producing the pulse signal of required frequency respectively；

Described VFTO combiner circuit carries out amplitude adjustment for the pulse signal that each pulse signal generator in pulse signals generator group respectively produces, and is overlapped each pulse signal after amplitude adjustment processing and exporting required VFTO after phase adjusted process；

Adopt high-temperature gas breakdown characteristics detecting device under described VFTO to carry out the method for high-temperature gas breakdown characteristics detection under VFTO, comprise the steps:

Step 1: regulate the spacing between anode electrode plate and cathode electrode plate, reach desirable value；

Step 2: gas confinement chamber is carried out evacuation process by gas charge and discharge and recovery unit；

Step 3: gas charge and discharge and recovery unit are filled with the gas of required pressure to gas confinement indoor；

Step 4: resistance wire is powered by voltage source；

Step 5: gas confinement indoor gas temperature measured by temperature measurer；

Step 6: judge whether gas confinement indoor gas temperature reaches target temperature, is then perform step 7, no, then turn execution step 4；

Step 7: close voltage source, stops powering to resistance wire；

Step 8:VFTO generation unit antianode battery lead plate simultaneously and cathode electrode plate load VFTO；

Step 9: the intensity of spectrum that spectrometer measurement gaseous plasma produces and wavelength are also sent to computer；

Step 10: whether change according to ammeter indicated value and judge whether gas punctures under VFTO, if ammeter indicated value changes, then think that gas punctures under VFTO, turn and go to perform step 11, if ammeter indicated value does not change, then think that gas does not puncture under VFTO, turn and go to perform step 9；

Step 11: gas confinement chamber is carried out evacuation process by gas charge and discharge and recovery unit；

Step 12: the various particle temperatures that the intensity of the spectrum that computer produces according to the gaseous plasma received and band meter calculate in plasma；

Step 13: computer calculates the distribution of various particles in gas breakdown process according to the various particle temperatures in gas plasma body, obtains the distribution function of various particles in gas breakdown process；

In gas breakdown process, the distribution of various particles is obtained by Boltzmann equation (1),

$\frac{\∂f}{\∂t}+v\·\frac{\∂f}{\∂r}+\mathrm{eE}\·\frac{\∂f}{\∂p}={\▿}_p\·s---\left(1\right)$

Wherein, s is the particle current density of momentum space, individual/m³；▽_pFor the s total differential to momentum；P is the momentum of particle, and unit is kg m/s；S is s at the axial component of α_α, s_αObtained by formula (2)；α axle is X-axis, or α axle is Y-axis, or α axle is Z axis；

$s_{\mathrm{\α}}={\mathrm{\σ}}_t{u}^2\·|v-v^{\′}|\∫\∫\∫(f\frac{{\∂f}^{\′}}{{\∂p}_{\mathrm{\β}}^{\′}}-f^{\′}\frac{\∂f}{{\∂p}_{\mathrm{\β}}})\×({(v-v^{\′})}^2{\mathrm{\δ}}_{\mathrm{\α\β}}-(v_{\mathrm{\α}}-{v_{\mathrm{\α}}}^{\′})(v_{\mathrm{\β}}-{v_{\mathrm{\β}}}^{\′}))d^3{p}^{\′}---\left(2\right)$

Wherein, σ_tFor transport cross-section, formula (3) obtain；U is reduced mass,M and m' respectively two momentum collided are the quality of the particle of p and particle that momentum is p', kg；V and v' respectively momentum is the particle rapidity of p and momentum is the particle rapidity of p', m/s；F is momentum is the distribution function of the particle of p；The distribution function that f ' is particle that momentum is p'；p′_βFor momentum p' at the axial component of β；β axle is X-axis, or β axle is Y-axis, or β axle is Z axis；p_βFor momentum p at the axial component of β；δ_αβFor unit tensor；v_αFor particle rapidity that momentum is p at the axial component of α, m/s；v_α' for the axial component of particle rapidity α that momentum is p', m/s；v_βFor particle rapidity that momentum is p at the axial component of β, m/s；v_β' for the axial component of particle rapidity β that momentum is p', m/s；

${\mathrm{\σ}}_t={\mathrm{\σ}}_e+{\mathrm{\σ}}_r=\frac{2\mathrm{\π}}{k^2}\underset{l=0}{\overset{\∞}{\mathrm{\Σ}}}(2l+1)(1-{\left|S_l\right|}^2)---\left(3\right)$

Wherein, σ_eFor elastic scattering cross-section；σ_rFor inelastic scattering cross section；K is the wave number of incoming particle, determines according to formula (4)；L is angular momentum, kg m²/s；S_lFor the mould random number less than 1, S_l=1 expression is completely absent this scattering, S_l=0 represents that the particle that angular momentum is l is absorbed completely；

Wherein,For planck constant；E is the energy of scattering particles, joule；m₁Being the quality of relatively lepton in two impingment particles, unit is kg；

Step 14: computer calculates the coefficient of viscosity of the diffusion coefficient of particle, the electrical conductivity of particle and particle respectively according to the distribution function of particles various in gas breakdown process.

Beneficial effect: under the VFTO of the present invention, high-temperature gas breakdown characteristics detecting device and method have following advantage compared with prior art:

1) with in the past that the macroscopic view parameters such as the research of breakdown process simply measurement breakdown voltage is different, this device is from the breakdown process of the angle detected gas of microcosmic, by the light intensity in spectrometer measurement breakdown process and wavelength, obtain the particle temperature in breakdown process, and be applied in the research method that the present invention proposes, obtain the viscosity of particle, electrical conductivity, diffusion coefficient.

2) according to, in GIS, VFTO, the break performance of harm chopper being produced.At present almost without for the research of gas breakdown process under this extreme condition of VFTO, and the present invention can realize the detection of gas breakdown process when VFTO.

3) in gas breakdown process, between particle, there is the collision of complexity, the distribution of particle needs to describe with Non-Boltzmann distrubution, very high frequency due to VFTO, in its breakdown process different when the collision of particle and power frequency, so needing the collision term correction to Boltzmann when solving particle density distribution in breakdown process when VFTO.The collision term of Boltzmann equation, according to the feature of particle encounter under VFTO, is corrected by the present invention.

Accompanying drawing explanation

Fig. 1 be one embodiment of the present invention VFTO under the annexation schematic diagram of high-temperature gas breakdown characteristics detecting device；

Fig. 2 be one embodiment of the present invention gas confinement chamber used by the structural representation of ring flange；

Fig. 3 is the gas charge and discharge annexation schematic diagram with recovery unit of one embodiment of the present invention: the structural representation that (a) is vacuumized part；B structural representation that () is injection section；

Fig. 4 is the circuit theory diagrams of the VFTO generation unit of one embodiment of the present invention；

Fig. 5 be one embodiment of the present invention VFTO under the flow chart of high-temperature gas breakdown characteristics detection method.

Detailed description of the invention

Below in conjunction with accompanying drawing, one embodiment of the present invention is elaborated.

High-temperature gas breakdown characteristics detecting device under the VFTO of present embodiment, as it is shown in figure 1, include: gas confinement chamber 7, heating unit, discharge cell, spectrogrph 5, temperature measurer 3, gas charge and discharge and recovery unit 1, voltage source 12, VFTO generation unit 11, ammeter 16 and computer 15；

Described gas confinement chamber 7 is the cylinder barrel shaped structure closed, and for filling gas, adopts adiabatic glass material to make, and wall thickness is about 20mm, and the barrel-shaped intracavity diameter of gas confinement chamber 7 cylinder is about 170mm, is highly about 400mm；Gas confinement chamber 7 tip position is connected with upper flange plate 6, and gas confinement chamber 7 bottom position is connected with lower flange 10；Upper flange plate 6 is identical with the structure of lower flange 10, as shown in Figure 2, open the circle groove that width is 20mm at upper flange plate 6 respectively apart from 85mm place, its center of circle apart from 85mm place, its center of circle with at lower flange 10, in two circle grooves, place rubber gasket 17 respectively.Upper flange plate 6 and lower flange 10 connect gas confinement chamber all in the way to insert and are carried out surrounding fixed by bolt 18.For hot test, rubber seal 17 adopts FFKM, has very strong high-temperature stability.

Described heating unit includes resistance wire 13 and potsherd 9；Described resistance wire 13 is for being heated the gas in gas confinement chamber, for increasing heating surface area and making gas be heated evenly, resistance wire is twisted into stock, and tiling is arranged on the surface location of gas confinement chamber intracavity bottom lower flange 10；The material of resistance wire 13 is ferrum-chromium-aluminum OCr27Al7MO2, can the maximum temperature of heated air be 1400 DEG C；The ceramic material on resistance wire 13 surface is alumina ceramic plate, and model is TO-247.Breakdown process plasma measurement is produced interference by the metallic vapour produced when avoiding resistance wire 13 to heat, tiled the potsherd 9 of a floor height heat conductivity on resistance wire 13 surface, isolates between the metallic vapour and the tested gas that produce during for resistance wire 13 is heated；Owing to the ductility of pottery is poor, for ease of installing, the diameter 4mm less of the internal diameter of gas confinement chamber 7 of potsherd 9, and relative to gas confinement chamber 7 internal diameter, 4mm is only small amount, and resistance wire is arranged in below potsherd, thus will not plasma measurement produce impact.

Described discharge cell includes anode electrode plate 14 and cathode electrode plate 8；Described anode electrode plate 14 and cathode electrode plate 8 are separately mounted on the centre position of gas confinement chamber 7 internal chamber wall, and anode electrode plate 14 and cathode electrode plate 8 staggered relatively, and the spacing scalable between anode electrode plate 14 and cathode electrode plate 8；Anode electrode plate 14 and cathode electrode plate 8 are disc plate electrode, and material is copper, and diameter is 20mm,

The probe 4 of described spectrogrph 5 is inserted in gas confinement chamber 7 inner chamber and is placed between anode electrode plate 14 and cathode electrode plate 8, it is positioned at the position of 5mm above anode electrode plate 14 and above cathode electrode plate 8, and the part that probe 4 is placed in gas confinement chamber 7 inner chamber arranges a convex lens, it is possible to increase the measurement scope of probe 4.Measured the spectral intensity when emission spectrum that gaseous plasma produces acquires gas breakdown under VFTO and spectral wavelength by spectrogrph 5, utilize light intensity ratio method to obtain the temperature of each particle in gaseous plasma.What the spectrogrph 5 in present embodiment adopted is AvaSpec-ULS2048-x-USB2 double-channel spectrometer, can record wave-length coverage is that 200-1100nm, A/D conversion adopts 16 1MHZ, and minimum response time is 0.1ms, detector adopts CCD linear array, and pixel is 2*3648.

Described temperature measurer 3 is arranged on gas confinement chamber 7 inner cavity top position, for measuring the temperature of heated gas；What the temperature measurer 3 in present embodiment adopted is fixed infrared temperature detector, and model is SCIT-2MK2A, and temperature-measuring range is 600 DEG C-2000 DEG C, and aiming mode is optical visual；It is bolted on upper flange plate 6.Owing to infrared radiation thermometer 3 can only survey the temperature of a bit, may result in measurement result and have very big error, the present invention adopts multiangular measurement, with bolt, infrared thermometer is fixed on bearing, the temperature of multiple directions can be measured, measure once every 15 degree, and measured value is averaged as the gas temperature in cavity.

Described gas charge and discharge, processes for the charge and discharge of gas, the recovery of gas and the evacuation of gas confinement chamber by trachea 2 and gas confinement chamber 7 inner space with recovery unit 1；For preventing inflation and evacuation seasonal epidemic pathogens body drain from going out, in present embodiment, gas charge and discharge and recovery unit 1 by picking out a threaded rustless steel trachea 2 and gas confinement chamber inner space on upper flange plate 6, during for testing, by the gas insufflation gas sealing chamber of certain air pressure；After experiment terminates, by gas evacuation indoor for gas confinement to prevent harmful gas from polluting.

For preventing inflation and evacuation seasonal epidemic pathogens body drain from going out, in present embodiment, gas charge and discharge is connected with gas confinement chamber 7 by trachea 2 with recovery unit 1, and there is screw thread on trachea 2 surface, the stainless steel tube compact siro spinning technology that it and gas confinement chamber 7 upper flange plate 6 pick out；During experiment, by the gas insufflation gas sealing chamber 7 of certain air pressure, after experiment terminates, by the gas evacuation in gas confinement chamber 7 to prevent harmful gas from polluting；Gas charge and discharge and recovery unit 1 include vacuum extractor and aerating device；Vacuumized part includes gas recycling can 25, vacuometer 19, vacuum pump 24, air gauge 22, valve 20, valve 21 and valve 23, as shown in Fig. 3 (a), during gas confinement chamber 7 evacuation, valve 20, valve 21, valve 23 are opened, gas is extracted out by vacuum pump 24, and maximum vacuum is 10Pa；Injection section includes air accumulator 29, filter 28, compressor 27, air gauge 26 and valve 30, as shown in Fig. 3 (b), when gas confinement chamber 7 is inflated, the gas of air accumulator 26 is by filter 28 and compressor 27 insufflation gas sealing chamber 7, and highest pressure is 3.8Mpa；

Two outfans of described voltage source 12 connect two terminals of resistance wire 13 respectively, for powering for resistance wire 13, make resistance wire 13 generate heat, make gas before not discharging quickly reach higher temperature；What the voltage source 12 in present embodiment adopted is GQ-AD type 3000W rearrangeable switch power supply, maximum voltage 1500V, maximum current 2000A.

Described VFTO generation unit, as shown in Figure 4, including pulse trigger group 31, pulse generator group 32 and VFTO combiner circuit 33；The pulse trigger that in present embodiment, n pulse trigger in pulse trigger group 31 all adopts model to be 501003CDB (CD3), the pulse generator of the complete solid state pulse power source that n pulse generator in pulse generator group 32 all adopts model to be SPG200；

Described pulse trigger group 31 includes n pulse trigger, for controlling the output frequency of pulse generator group 32；Described pulse generator group 32 includes n pulse generator, for producing the pulse signal of certain frequency；The input of each pulse trigger in described pulse trigger group 31 outfans different from computer 15 respectively connect；The outfan of each pulse trigger in described pulse trigger group 31 is connected with the input of each pulse generator in pulse generator group 32 respectively；The outfan of each pulse generator in described pulse generator group 32 connects each input of VFTO combiner circuit 33 respectively, and the outfan of VFTO combiner circuit 33 is connected by the link of ammeter 16 with anode electrode plate 14 and gas confinement chamber 7 as the outfan of VFTO generation unit 11；The zero potential end of described VFTO generation unit 11 is connected with the link of cathode electrode plate 8 and gas confinement chamber 7；

Resistance R1 it is in series with respectively between each input and the negative input end of first order operational amplifier 34 of described VFTO combiner circuit 33, resistance R2, ..., resistance Rn, as shown in Figure 4, it is parallel with resistance Rn+1 between negative input end and its outfan of first order operational amplifier 34, the positive input terminal of first order operational amplifier 34 passes through resistance Rn+2 ground connection, the outfan of first order operational amplifier 34 connects the negative input end of second level operational amplifier 35 by resistance Rn+3, it is parallel with resistance Rn+4 between negative input end and its outfan of second level operational amplifier 35, the positive input terminal of second level operational amplifier 35 passes through resistance Rn+5 ground connection.

The VFTO that present embodiment Computer 15 simulation calculation produces when going out isolator operation in certain GIS, and this VFTO is decomposed into the nanosecond pulse signal of n different amplitudes, different frequency；nullThe frequency values of each pulse signal decomposited is set in each pulse trigger in pulse trigger group 31 by computer 15 respectively，Each pulse trigger in pulse trigger group 31 produces pulse signal respectively according to each pulse generator in set pulse signal frequency value trigger generator group 32 respectively，Pulse signal is sent to each input of VFTO combiner circuit 33 by each pulse generator in pulse generator group 32 respectively，Resistance R1 in VFTO combiner circuit 33、R2、…、The amplitude of each pulse signal received is adjusted by each pulse signal amplitude that Rn decomposites according to computer 15 respectively，Through resistance R1、R2、…、N pulse signal after Rn adjustment obtains required VFTO at VFTO combiner circuit 33 outfan out end after first order operational amplifier 34 superposition and second level operational amplifier 35 regulate phase place，Namely identical with the VFTO that computer 15 simulation calculation goes out or be close.

The frequency respectively f1 of the nanosecond pulse signal that each pulse generator in pulse generator group 32 produces respectively, f2 ..., fn, its voltage respectively u₁、u₂、…、u_n, after first order operational amplifier 34 superposition, obtain u_n+1,

$u_{n+1}=-\frac{R_{n+1}}{R_1}{u}_1-\frac{R_{n+1}}{R_2}{u}_2-...-\frac{R_{n+1}}{R_n}{u}_n---\left(5\right)$

u_n+1U is obtained after second level operational amplifier 35 regulates phase place_n+2, i.e. VFTO

$u_{n+2}=-\frac{R_{n+4}}{R_{n+3}}{u}_{n+1}=\mathrm{VFTO}---\left(6\right)$

Wherein, R_n+3、R_n+4For resistance, unit is Ω, and R_n+4=R_n+3；

The distribution of various particles and calculate the diffusion coefficient of particle according to the distribution function of particles various in gas breakdown process respectively in the intensity of spectrum that the gaseous plasma that described computer 15 sends for receiving spectrogrph 5 produces and the wavelength of spectrum the various particle temperatures calculating in gas plasma body and gas breakdown process, the electrical conductivity of particle and the coefficient of viscosity of particle, and the VFTO for producing during isolator operation in simulation calculation GIS, and the VFTO of acquisition is decomposed into multiple identical amplitude, the nanosecond pulse signal of different cycles each pulse trigger in being sent respectively to the pulse trigger group 31 of VFTO generation unit.

Adopt high-temperature gas breakdown characteristics detecting device under the VFTO of present embodiment to carry out the method for high-temperature gas breakdown characteristics detection under VFTO, comprise the steps:

Step 1: regulate spacing between anode electrode plate 14 and cathode electrode plate 8 to 5mm；

Step 2: gas confinement chamber 7 is carried out evacuation process by gas charge and discharge and recovery unit 1；

Step 3: gas charge and discharge and recovery unit 1 are filled with the SF6 gas of 0.1MPa in gas confinement chamber 7；

Step 4: voltage source 12 is powered to resistance wire 13 so that it is heating；

Step 5: measured value, from the temperature of SF6 in multiple angular surveying gas confinement chamber 7, is averaged as the gas temperature in sealing chamber 7 by infrared radiation thermometer 3；

Step 6: judge whether gas temperature reaches target temperature 1000 °, is then perform step 7, no, then turn execution step 4；

Step 7: close voltage source 12, stops powering to resistance wire 13；

Step 8:VFTO generation unit 11 antianode battery lead plate 14 and cathode electrode plate 8 simultaneously load VFTO；

Step 9: spectrogrph 5 is measured the spectral intensity of plasma in SF6 gas and wavelength and is sent to computer 15；

Step 10: whether change according to ammeter 16 indicated value and judge whether SF6 gas punctures under VFTO, if ammeter 16 indicated value changes, then it is assumed that gas breakdown, if ammeter 16 indicated value does not change, then it is assumed that gas does not puncture；

Step 11: the remaining SF6 gas in gas confinement chamber 7 is carried out evacuation process by gas charge and discharge and recovery unit 1；

Step 12: the various particle temperatures that computer calculates in plasma according to spectral intensity and the band meter of the SF6 gaseous plasma generation received；

Step 13: computer 15 calculates the distribution of various particles in gas breakdown process according to the various particle temperatures in gas plasma body, obtains the distribution function of various particles in gas breakdown process；

In gas breakdown process under VFTO, particle momentum change in collision process is only small, it is possible to the process described by collision integral is processed as the diffusion in momentum space, and collision term can be write as:

$c\left(f\right)=-{\▿}_p\·s=-\frac{{\∂s}_{\mathrm{\α}}}{{\∂p}_{\mathrm{\α}}}---\left(7\right)$

Wherein, s is the particle current density of momentum space, individual/m³, represent the population in unit volume unit in momentum space；▽_pFor the s total differential to momentum；s_αFor s at the axial component of α, α axle is X-axis, or α axle is Y-axis, or α axle is Z axis；P is the momentum of particle, and unit is kg m/s；p_αFor momentum p at the axial component of α；It is that p' is at d for particle that momentum is p with momentum³The Collision Number that between particle in p', time per unit occurs is

w(p+q/2,p′-q/2；q)·f(p)·f′(p′)d³qd³Wherein, q is momentum transfer to p ' (8)；The momentum that p ' is particle, unit is kg m/s；W is w function, and w function is expressed by the momentum p and momentum p' and momentum transfer q colliding two particle；

According to detailed balance condition, the exchange of function w initiating particle and eventually end particle is symmetrical

w(p+q/2,p′-q/2；Q)=w (p+q/2, p '-q/2；-q)(9)

Consider that momentum space point P is perpendicular to the unit are of α axle, according to definition, particle current density s_αIt it is the population from left to right exceeded through this area from right to left through this area ratio the unit interval.If a particle accepts the α component of momentum in an impact equal to q_α, this collision as a result, for from left to right through the particle of this area, before collision, their this component value is positioned at from p_α-q_αTo P_α, therefore, the population through this area is from left to right

$\mathrm{\Σ}\underset{q_{\mathrm{\α}}>0}{\∫}{d}^{3}q\∫d^3{p}^{\′}\underset{p_{\mathrm{\α}}-q_{\mathrm{\α}}}{\overset{p_{\mathrm{\α}}}{\∫}}w(p+q/2,p^{\′}-q/2;q)f\left(p\right)f^{\′}\left(p^{\′}\right){\mathrm{dp}}_{\mathrm{\α}}---\left(10\right)$

Wherein, f is momentum is the distribution function of the particle of p；The distribution function that f ' is particle that momentum is p'；

Population through this area is from left to right

$\mathrm{\Σ}\underset{q_{\mathrm{\α}}>0}{\∫}{d}^{3}q\∫d^3{p}^{\′}\underset{p_{\mathrm{\α}}-q_{\mathrm{\α}}}{\overset{p_{\mathrm{\α}}}{\∫}}w(p+q/2,p^{\′}-q/2;-q)f(p+q)f^{\′}(p^{\′}-q){\mathrm{dp}}_{\mathrm{\α}}---\left(11\right)$

By formula (8) it can be seen that the w in two integrations is identical, therefore the difference of these integrations contains by the difference in long-pending expression formula

f(p)f′(p′)-f(p+q)f′(p′-q)

Owing to momentum transmission q is only small, it is possible to the power series to above-mentioned poor generated q, finally give

$s_{\mathrm{\α}}=\mathrm{\Σ}\underset{q_{\mathrm{\α}}>0}{\∫}{d}^{3}q\∫d^3{p}^{\′}\underset{p_{\mathrm{\α}}-q_{\mathrm{\α}}}{\overset{p_{\mathrm{\α}}}{\∫}}w(p,p^{\′};q)[f\left(p\right)\frac{\∂f^{\′}\left(p^{\′}\right)}{{\∂p}_{\mathrm{\β}}^{\′}}-f^{\′}\left(p^{\′}\right)\frac{\∂f\left(p\right)}{{\∂p}_{\mathrm{\β}}}]q_{\mathrm{\β}}{q}_{\mathrm{\α}}{d}^3{p}^{\′}---\left(12\right)$

Wherein, p '_βFor momentum p' at the axial component of β；β axle is X-axis, or β axle is Y-axis, or β axle is Z axis；p_βFor momentum p at the axial component of β；

Introduce collision cross-section and replace function w

wd³Q=| v-v ' | d σ (13)

Therefore often class particle has following form at the momentum flow density of momentum space

$s_{\mathrm{\α}}=\mathrm{\Σ}\∫[f\left(p\right)\frac{\∂f^{\′}\left(p^{\′}\right)}{{\∂p}_{\mathrm{\β}}^{\′}}-f^{\′}\left(p^{\′}\right)\frac{\∂f\left(p\right)}{{\∂p}_{\mathrm{\β}}}]B_{\mathrm{\α\β}}{d}^3{p}^{\′}---\left(14\right)$

$B_{\mathrm{\α\β}}=\frac{1}{2}\∫q_{\mathrm{\α}}{q}_{\mathrm{\β}}|v-v^{\′}|\mathrm{d\σ}---\left(15\right)$

Wherein, B_αβFor the amount of particle encounter, it it is a tensor；q_αFor the axial momentum transfer of α；q_βFor the axial momentum transfer of β；V and v' respectively momentum is the particle rapidity of p and momentum is the particle rapidity of p', m/s；Low-angle is offset, B_αβ(v_β-v_β')=0, therefore

$B_{\mathrm{\α\β}}=\frac{1}{2}B[{\mathrm{\δ}}_{\mathrm{\α\β}}-\frac{(v_{\mathrm{\α}}-v_{\mathrm{\α}}^{\′})(v_{\mathrm{\β}}-v_{\mathrm{\β}}^{\′})}{{(v-v^{\′})}^2}]---\left(16\right)$

B=B_αα=u²|v-v′|³σ_t

Wherein, B_ααFor B_αβScalar form；

In gas breakdown process, the distribution of various particles is obtained by Boltzmann equation (1),

$\frac{\∂f}{\∂t}+v\·\frac{\∂f}{\∂r}+\mathrm{eE}\·\frac{\∂f}{\∂p}={\▿}_p\·s---\left(1\right)$

Wherein, s is the particle current density of momentum space, individual/m³；▽_pFor the s total differential to momentum；P is the momentum of particle, and unit is kg m/s；S is s at the axial component of α_α, s_αObtained by formula (2)；α axle is X-axis, or α axle is Y-axis, or α axle is Z axis；

$s_{\mathrm{\α}}={\mathrm{\σ}}_t{u}^2\·|v-v^{\′}|\∫\∫\∫(f\frac{{\∂f}^{\′}}{{\∂p}_{\mathrm{\β}}^{\′}}-f^{\′}\frac{\∂f}{{\∂p}_{\mathrm{\β}}})\×({(v-v^{\′})}^2{\mathrm{\δ}}_{\mathrm{\α\β}}-(v_{\mathrm{\α}}-{v_{\mathrm{\α}}}^{\′})(v_{\mathrm{\β}}-{v_{\mathrm{\β}}}^{\′}))d^3{p}^{\′}---\left(2\right)$

Wherein, σ_tFor transport cross-section, formula (3) obtain；U is reduced mass,M and m' respectively two momentum collided are the quality of the particle of p and particle that momentum is p', kg；V and v' respectively momentum is the particle rapidity of p and momentum is the particle rapidity of p', m/s；F is momentum is the distribution function of the particle of p；The distribution function that f ' is particle that momentum is p'；p′_βFor momentum p' at the axial component of β；β axle is X-axis, or β axle is Y-axis, or β axle is Z axis；p_βFor momentum p at the axial component of β；δ_αβFor unit tensor；v_αFor particle rapidity that momentum is p at the axial component of α, m/s；v_α' for the axial component of particle rapidity α that momentum is p', m/s；v_βFor particle rapidity that momentum is p at the axial component of β, m/s；v_β' for the axial component of particle rapidity β that momentum is p', m/s；

${\mathrm{\σ}}_t={\mathrm{\σ}}_e+{\mathrm{\σ}}_r=\frac{2\mathrm{\π}}{k^2}\underset{l=0}{\overset{\∞}{\mathrm{\Σ}}}(2l+1)(1-{\left|S_l\right|}^2)---\left(3\right)$

Wherein, σ_eFor elastic scattering cross-section；σ_rFor inelastic scattering cross section；K is the wave number of incoming particle, determines according to formula (4)；L is angular momentum, kg m²/s；S_lFor the mould random number less than 1, S_l=1 expression is completely absent this scattering, S_l=0 represents that the particle that angular momentum is l is absorbed completely；

Wherein,For planck constant；E is the energy of scattering particles, joule；m₁Being the quality of relatively lepton in two impingment particles, unit is kg；

The concrete operations mode solving formula (1) Boltzmann equation is: zoning is divided into macroscopic view little (can replace with a bit), the fritter of microcosmic big (comprising abundant particle), plasma in each fritter is balance, can represent with same distribution function, it is linearly unbalanced between fritter and fritter, if

F=f⁰(1+h) (17) wherein, f⁰For local ANALOGY OF BOLTZMANN DISTRIBUTION；H is change；

Formula (17) is brought into formula (1) obtain

$[\frac{\∂}{\∂t}+v\·\frac{\∂}{\∂r}+\mathrm{eE}\·\frac{\∂}{\∂p}](f^0+f^{0}h)=f^0{\▿}_p\·s\·h---\left(18\right)$

When momentum change is only small

$f^0=n\left(r\right){\left[2\mathrm{\π}{k}_{B}t(r,t)\right]}^{-\frac{3}{2}}\exp [-\frac{m{|v-u\left(r\right)|}^2}{{2\mathrm{mk}}_{B}T(r,t)}]---\left(19\right)$

Wherein, u (r)=<v>, for the average speed of localized particle, unit is m/s；k_BFor Planck's constant；(r, t) is local temperature to T, and unit is K, and it is relevant with particles spatial position r and time t, and its value can be obtained by the detecting device in the present invention；The distribution function of each particle is obtained by solving equation (18).

Step 14: computer calculates the coefficient of viscosity of the diffusion coefficient of particle, the electrical conductivity of particle and particle respectively according to the distribution function of particles various in gas breakdown process.

Diffusion coefficient D, conductivityσ and coefficient of viscosity η are obtained by formula (20), formula (21) and formula (22)

$D=-\frac{1}{n}{\&Integral;\&Integral;\&Integral;d}^3{\mathrm{vfv}}_x\frac{1}{{\&dtri;}_p\&CenterDot;s}{v}_x---\left(20\right)$

$\mathrm{\&sigma;}=-\frac{e^2}{{2m}_2{k}_{B}T(r,t)}{\&Integral;\&Integral;\&Integral;d}^3{\mathrm{vfv}}_x\frac{1}{{\&dtri;}_p\&CenterDot;s}{v}_x---\left(21\right)$

$\mathrm{\&eta;}=-\frac{m_2}{k_{B}T(r,t)}{\&Integral;\&Integral;\&Integral;d}^3{\mathrm{vfv}}_x{v}_y\frac{1}{{\&dtri;}_p\&CenterDot;s^T}{v}_x{v}_y---\left(22\right)$

Wherein, n is population density, individual/m³；v_xFor the particle velocity component in X-direction, m/s；v_yFor the particle velocity component in Y direction, m/s；E is electronic band electricity, coulomb；m₂For the quality of all kinds of particles, Kg.

In SF6 gas step 13 obtained, the distribution of each particle is brought formula (20), formula (21) and formula (22) into and is obtained diffusion coefficient D, conductivityσ and coefficient of viscosity η.

Claims (10)

1. high-temperature gas breakdown characteristics detecting device under a VFTO, it is characterised in that: including:

Gas confinement chamber, heating unit, discharge cell, spectrogrph, temperature measurer, gas charge and discharge and recovery unit, voltage source, VFTO generation unit, ammeter and computer；

Described gas confinement chamber is the cylinder barrel shaped structure closed, and adopts adiabatic transparent material, for filling gas；

Described heating unit includes resistance wire and potsherd；Described resistance wire is arranged on gas confinement chamber intracavity bottom position；Described potsherd is laid on resistance wire surface；

Described discharge cell includes anode electrode plate and cathode electrode plate；Described anode electrode plate and cathode electrode plate are separately mounted on the centre position of gas confinement chamber internal chamber wall, and anode electrode plate and cathode electrode plate staggered relatively；

The probe of described spectrogrph is inserted in gas confinement chamber inner chamber and is placed between anode electrode plate and cathode electrode plate, and the outfan of spectrogrph connects an input of computer；

Described temperature measurer is arranged on gas confinement chamber inner cavity top position；

Described gas charge and discharge passes through trachea and gas confinement chamber inner space with recovery unit；

Two outfans of described voltage source connect two terminals of resistance wire respectively；

Described VFTO generation unit includes pulse trigger group, pulse generator group and VFTO combiner circuit；Described pulse trigger group includes multiple pulse trigger；Described pulse generator group includes multiple pulse generator；The input of each pulse trigger in described pulse trigger group outfans different from described computer respectively connect；The outfan of each pulse trigger in described pulse trigger group is connected with the input of each pulse generator in pulse generator group respectively；The outfan of each pulse generator in described pulse generator group connects each input of VFTO combiner circuit respectively, and the outfan of VFTO combiner circuit is connected by the link of ammeter with anode electrode plate and gas confinement chamber as the outfan of VFTO generation unit；The zero potential end of described VFTO generation unit is connected with the link of cathode electrode plate and gas confinement chamber.

2. high-temperature gas breakdown characteristics detecting device under VFTO according to claim 1, it is characterised in that: described resistance wire is for being heated the gas in gas confinement chamber；Described potsherd is for isolating between metallic vapour and the tested gas of generation during to Resistant heating.

3. high-temperature gas breakdown characteristics detecting device under VFTO according to claim 1, it is characterised in that: the spacing scalable between anode electrode plate and the cathode electrode plate of described discharge cell.

4. high-temperature gas breakdown characteristics detecting device under VFTO according to claim 1, it is characterised in that: described spectrogrph is used for measuring the intensity of spectrum of gaseous plasma generation and the wavelength of spectrum and the intensity of the spectrum recorded and the wavelength of spectrum being sent to computer.

5. high-temperature gas breakdown characteristics detecting device under VFTO according to claim 1, it is characterised in that: described voltage source, for powering for resistance wire, makes resistance wire generate heat；Described temperature measurer is for measuring the temperature of heated gas.

6. high-temperature gas breakdown characteristics detecting device under VFTO according to claim 1, it is characterised in that: described gas charge and discharge and recovery unit are used for inflation and the evacuation process of gas confinement chamber.

7. high-temperature gas breakdown characteristics detecting device under VFTO according to claim 1, it is characterised in that:

The distribution of various particles and calculate the diffusion coefficient of particle according to the distribution function of particles various in gas breakdown process respectively in the intensity of spectrum that the gaseous plasma that described computer sends for receiving spectrogrph produces and the wavelength of spectrum the various particle temperatures calculating in plasma and gas breakdown process, the electrical conductivity of particle and the coefficient of viscosity of particle, and be used for emulating acquisition VFTO, and each pulse trigger in the VFTO of acquisition being decomposed into the nanosecond pulse signal of multiple different cycles and being sent respectively to the pulse trigger group of VFTO generation unit.

8. high-temperature gas breakdown characteristics detecting device under VFTO according to claim 1, it is characterised in that:

Each pulse trigger in described pulse trigger group is for controlling the output frequency of each pulse generator in pulse generator group respectively；Each pulse generator in described pulse generator group is for producing the pulse signal of required frequency respectively.

9. high-temperature gas breakdown characteristics detecting device under VFTO according to claim 1, it is characterised in that:

The pulse that described VFTO combiner circuit produces for each pulse signal generator in pulse signals generator group respectively

Signal carries out amplitude adjustment, and is overlapped each pulse signal after amplitude adjustment processing and exporting required VFTO after phase adjusted process.

10. adopt high-temperature gas breakdown characteristics detecting device under the VFTO described in claim 1 to carry out the method for high-temperature gas breakdown characteristics detection under VFTO, it is characterised in that: comprise the steps:

Step 1: regulate the spacing between anode electrode plate and cathode electrode plate, reach desirable value；

Step 2: gas confinement chamber is carried out evacuation process by gas charge and discharge and recovery unit；

Step 3: gas charge and discharge and recovery unit are filled with the gas of required pressure to gas confinement indoor；

Step 4: resistance wire is powered by voltage source；

Step 5: gas confinement indoor gas temperature measured by temperature measurer；

Step 6: judge whether gas confinement indoor gas temperature reaches target temperature, is then perform step 7, no, then turn execution step 4；

Step 7: close voltage source, stops powering to resistance wire；

Step 8:VFTO generation unit antianode battery lead plate simultaneously and cathode electrode plate load VFTO；

Step 9: the intensity of spectrum that spectrometer measurement gaseous plasma produces and wavelength are also sent to computer；

Step 10: whether change according to ammeter indicated value and judge whether gas punctures under VFTO, if ammeter indicated value changes, then think that gas punctures under VFTO, turn and go to perform step 11, if ammeter indicated value does not change, then think that gas does not puncture under VFTO, turn and go to perform step 9；

Step 11: gas confinement chamber is carried out evacuation process by gas charge and discharge and recovery unit；

Step 12: the various particle temperatures that the intensity of the spectrum that computer produces according to the gaseous plasma received and band meter calculate in plasma；

Step 13: computer calculates the distribution of various particles in gas breakdown process according to the various particle temperatures in gas plasma body, obtains the distribution function of various particles in gas breakdown process；

In gas breakdown process, the distribution of various particles is obtained by Boltzmann equation (1),

$\frac{\&part;f}{\&part;t}+v\&CenterDot;\frac{\&part;f}{\&part;r}+eE\&CenterDot;\frac{\&part;f}{\&part;p}={\&dtri;}_p\&CenterDot;s---\left(1\right)$

Wherein, s is the particle current density of momentum space, and unit is individual/m³；T is the time, and unit is the second；R is the position of particle, and unit is rice；▽_pFor the s total differential to momentum；P is the momentum of particle, and unit is kg m/s；S is s at the axial component of α_α, s_αObtained by formula (2)；α axle is X-axis, or α axle is Y-axis, or α axle is Z axis；

$s_{\mathrm{\&alpha;}}={\mathrm{\&sigma;}}_t{u}^2\&CenterDot;\left|v-v^{\&prime;}\right|\&Integral;\&Integral;\&Integral;(f\frac{\&part;f^{\&prime;}}{\&part;p_{\mathrm{\&beta;}}^{\&prime;}}-f^{\&prime;}\frac{\&part;f}{\&part;p_{\mathrm{\&beta;}}})\&times;({\left(v-v^{\&prime;}\right)}^2{\mathrm{\&delta;}}_{\mathrm{\&alpha;}\mathrm{\&beta;}}-(v_{\mathrm{\&alpha;}}-{v_{\mathrm{\&alpha;}}}^{\&prime;}\left)\right(v_{\mathrm{\&beta;}}-{v_{\mathrm{\&beta;}}}^{\&prime;}\left)\right)d^3{p}^{\&prime;}---\left(2\right)$

Wherein, σ_tFor transport cross-section, formula (3) obtain；U is reduced mass,M and m' respectively two momentum collided are the quality of the particle of p and particle that momentum is p', and unit is kg；V and v' respectively momentum is the particle rapidity of p and momentum is the particle rapidity of p', and unit is m/s；F is momentum is the distribution function of the particle of p；The distribution function that f ' is particle that momentum is p'；p′_βFor momentum p' at the axial component of β；β axle is X-axis, or β axle is Y-axis, or β axle is Z axis；p_βFor momentum p at the axial component of β；δ_αβFor unit tensor；v_αFor particle rapidity that momentum is p at the axial component of α, unit is m/s；v_α' for the axial component of particle rapidity α that momentum is p', unit is m/s；v_βFor particle rapidity that momentum is p at the axial component of β, unit is m/s；v_β' for the axial component of particle rapidity β that momentum is p', unit is m/s；

${\mathrm{\&sigma;}}_t={\mathrm{\&sigma;}}_e+{\mathrm{\&sigma;}}_r=\frac{2\mathrm{\&pi;}}{k^2}\underset{l=0}{\overset{\mathrm{\&infin;}}{\&Sigma;}}(2l+1)(1-|S_l{|}^2)---\left(3\right)$

Wherein, σ_eFor elastic scattering cross-section；σ_rFor inelastic scattering cross section；K is the wave number of incoming particle, determines according to formula (4)；L is angular momentum, and unit is kg m²/s；S_lFor the mould random number less than 1, S_l=1 expression is completely absent this scattering, S_l=0 represents that the particle that angular momentum is l is absorbed completely；

Wherein,For planck constant；E is the energy of scattering particles, and unit is joule；m₁Being the quality of relatively lepton in two impingment particles, unit is kg；

Step 14: computer calculates the coefficient of viscosity of the diffusion coefficient of particle, the electrical conductivity of particle and particle respectively according to the distribution function of particles various in gas breakdown process.