CN101221245A - Correlated measuring method for ion average velocity of orienting plasma beam - Google Patents

Abstract

The invention discloses a related measurement method of the ion average speed of a directional plasma beam, which relates to a method for measuring the ion average speed of a directional plasma beam with density fluctuation property and aims at solving the problems that existing measurement methods have bigger error and more complex measurement process and cannot acquire the property of ion average speed change in the microsecond magnitude. The method of the invention consists of the following steps: step one, a steady plasma engine is started and adjusted to a state of stable discharging; step two, a positive bias power source is adjusted to lead the voltage loaded on two probes to be respectively in an electronic saturation region of electric current; step three, an oscillograph is started and adjusted to display a low-frequency oscillator signal clearly; step four, the data signal of the two probes in a same time section is recorded when the steady plasma engine works in a steady state; step five, the time difference when the relativity of the two probe signals is strongest is searched; step six, the ion average speed of the directional plasma beam is computed according to the formula that Vi equals to the result of L divided by Delta Tau.

Description

The relevant measurement method of directional plasma beam ion average velocity

Technical field

The present invention relates to the method that a kind of measurement has the directional plasma beam ion average velocity of density fluctuation characteristic.

Background technology

The directional plasma bundle has been widely used in fields such as etching processing and space flight propelling, and the average jet velocity of ion is one of important measurement index of directional plasma, but its measurement is a difficult problem, especially its dynamic perfromance always.

Steady-state plasma engine (SPT) is a kind of of electric propulsion device, is widely used in fields such as high rail satellite pose maintenance, track transfer, survey of deep space.It is working medium from inert gas that SPT adds the thermoelectron incoming call by electric field, and formed plasma is quickened ejection by electric field again, forms high speed directional plasma jet, and its specific impulse (being the average spouting velocity of ion with respect to device) can reach more than the 2000s.Specific impulse is the physical quantity that must measure as an angle of rake important indicator.

Traditional specific impulse is measured generally two kinds: the first adopts that thrust is counter to be pushed away, formed thrust when at first measuring the work of directional plasma bundle, and then counter the pushing away of formula below utilizing obtains specific impulse:

$I=\frac{F}{\stackrel{\·}{m}}$

Wherein F is a motor power,

Be the mass rate of Working medium gas, adopt this method, its measuring accuracy will depend critically upon thrust F and gas mass flow

Accurate measurement, but the thrust of SPT has only tens to tens milli oxen, also only several milligrams of mass rates, this makes their measurement all very difficult, also can there be very big error in the specific impulse of calculating gained in view of the above naturally; The secondth, the multiple-grid sonde method adopts the multiple-grid probe can obtain ion energy distribution function, so just can utilize the method for integration to obtain ion average velocity, but in fact the measuring process of ion energy distribution function is very loaded down with trivial details, and measuring accuracy neither be very high.The more important thing is and adopt above these two kinds of methods can not obtain the variation characteristic of the ion average velocity of microsecond magnitude at all, and this dynamic perfromance plays very significant effects to the various physical mechanisms of studying SPT inside.

Summary of the invention

The present invention is big for the error that solves the existing method of measuring the average jet velocity of ion and exist, measuring process is more loaded down with trivial details, precision is lower, can not obtain the problem of variation characteristic of the ion average velocity of microsecond magnitude, and a kind of relevant measurement method of directional plasma beam ion average velocity is provided.Finish the device that this method adopts following structure, this device is by steady-state plasma engine 1, positive bias power supply 2, oscillograph 3, the first probe 4-1, the second probe 4-2, the first resistance 5-1, the second resistance 5-2 and power supply 6 are formed, the first probe 4-1 and the second probe 4-2 are separately positioned in the plume district of steady-state plasma engine 1, the left and right sides central point of the upper surface of the first probe 4-1 and the second probe 4-2 all is positioned on the central axis up and down of steady-state plasma engine 1, first end of the output terminal of the first probe 4-1 and the first resistance 5-1 all is connected with the first input end of oscillograph 3, first end of the output terminal of the second probe 4-2 and the second resistance 5-2 all is connected with second input end of oscillograph 3, second end of the first resistance 5-1, second end of the second resistance 5-2 all is connected with the positive terminal of positive bias power supply 2 with the power input of oscillograph 3, the positive terminal of power supply 6 is connected with the positive terminal of steady-state plasma engine 1, and the negative pole end of power supply 6 and positive bias power supply 2 all is connected with the cathode compensation device 1-1 of steady-state plasma engine 1;

Method of the present invention is realized by following steps:

Step 1, start steady-state plasma engine 1 and be adjusted to the duty of stable discharging;

The voltage that step 2, adjustment positive bias power supply make the first probe 4-1 and the second probe 4-2 go up loading all is in the electronic current saturation region respectively;

Step 3, startup oscillograph 3 are also regulated displaying ratio and sweep time, make on the oscillograph 3 and can demonstrate oscillating signal clearly;

Step 4, record are also preserved the steady-state plasma engine 1 first probe 4-1 and second probe 4-2 data-signal on the section at one time under steady-working state;

Step 5, according to the The data correlation method of preserving in the step 4 calculate the first probe 4-1 and the second probe 4-2 the mistiming Δ τ of the number of accepting and believing correlativity when the strongest;

Step 6, calculate the ion average velocity of directional plasma bundle according to formula Vi=L/ Δ τ, wherein Vi represents the ion average velocity of directional plasma bundle, L represents the distance between the left and right sides central point of upper surface of the first probe 4-1 and the second probe 4-2, the mistiming when Δ τ represents that two signal correlations are the strongest between the signal.

The invention has the beneficial effects as follows: the measuring process of this method is simple, measuring result error is less, the Measuring Time yardstick can reach micron dimension, can obtain the variation characteristic of the ion average velocity on the microsecond magnitude, makes the research of various physical mechanisms of SPT inside more deep.

Description of drawings

Fig. 1 is the structural representation of the used metering circuit of method of the present invention; Fig. 2 is a method flow diagram of the present invention; Fig. 3 is the design sketch of embodiment two.

Embodiment

Embodiment one: referring to Fig. 1, Fig. 2, the method of finishing present embodiment adopts the device of following structure, this device is by steady-state plasma engine 1, positive bias power supply 2, oscillograph 3, the first probe 4-1, the second probe 4-2, the first resistance 5-1, the second resistance 5-2 and power supply 6 are formed, the first probe 4-1 and the second probe 4-2 are separately positioned in the plume district of steady-state plasma engine 1, the left and right sides central point of the upper surface of the first probe 4-1 and the second probe 4-2 all is positioned on the central axis up and down of steady-state plasma engine 1, first end of the output terminal of the first probe 4-1 and the first resistance 5-1 all is connected with the first input end of oscillograph 3, first end of the output terminal of the second probe 4-2 and the second resistance 5-2 all is connected with second input end of oscillograph 3, second end of the first resistance 5-1, second end of the second resistance 5-2 all is connected with the positive terminal of positive bias power supply 2 with the power input of oscillograph 3, the positive terminal of power supply 6 is connected with the positive terminal of steady-state plasma engine 1, and the negative pole end of power supply 6 and positive bias power supply 2 all is connected with the cathode compensation device 1-1 of steady-state plasma engine 1; It is 0.3mm that the described first probe 4-1 and the second probe 4-2 can adopt inner tungsten filament diameter, and external ceramic pipe diameter is the probe of 1mm, and it is the resistance of 1k Ω that the described first resistance 5-1 and the second resistance 5-2 can adopt resistance;

The method of present embodiment is realized by following steps:

Step 1, start steady-state plasma engine 1 and be adjusted to the duty of stable discharging;

The voltage that step 2, adjustment positive bias power supply make the first probe 4-1 and the second probe 4-2 go up loading all is in the electronic current saturation region respectively;

Step 3, startup oscillograph 3 are also regulated displaying ratio and sweep time, make on the oscillograph 3 and can demonstrate oscillating signal clearly;

Step 4, record are also preserved the steady-state plasma engine 1 first probe 4-1 and second probe 4-2 data-signal on the section at one time under steady-working state;

Step 5, according to the The data correlation method of preserving in the step 4 calculate the first probe 4-1 and the second probe 4-2 the mistiming Δ τ of the number of accepting and believing correlativity when the strongest;

Step 6, calculate the ion average velocity of directional plasma bundle according to formula Vi=L/ Δ τ, wherein Vi represents the ion average velocity of directional plasma bundle, L represents the distance between the left and right sides central point of upper surface of the first probe 4-1 and the second probe 4-2, the mistiming when Δ τ represents that two signal correlations are the strongest between the signal.

Embodiment two: referring to Fig. 3, the difference of present embodiment and embodiment one is to be realized by following steps:

Step 1, to start steady-state plasma engine 1 and be adjusted to sparking voltage Up be that 300V, anode gas supply flow are the duty of the stable discharging of 3mg/s, has the plasma of certain density to be full of the plume district from this moment;

Step 2, startup positive bias power supply 2, positive bias power supply 2 can adopt the adjustable D.C. regulated power supply of 0～100V, the output valve of adjusting positive bias power supply 2 is 40V, the distance that the left and right sides central point of the first probe 4-1 upper surface is arranged on the central point up and down of steady-state plasma engine 1 is the 15cm place, and the distance that the left and right sides central point of the second probe 4-2 upper surface is arranged on the central point up and down of steady-state plasma engine 1 is the 48cm place;

Step 3, startup oscillograph 3, oscillograph 3 can adopt Textronic TPS2024 type to isolate oscillograph, with the displaying ratio of oscillograph 3 be adjusted into 25 μ s/ lattice sweep time, make on the oscillograph 3 and can demonstrate oscillating signal clearly, can observe the time dependent image of plasma density that the first probe 4-1 and the second probe 4-2 detect respectively this moment;

Step 4, preserve steady-state plasma engine 1 under steady-working state the first probe 4-1 and the second probe 4-2 at one time the data-signal on the section be designated as Fig. 3 a, signal Phi 1 among Fig. 3 a is the signal that the first probe 4-1 obtains, and signal Phi 2 is the signal that the second probe 4-2 obtains;

Step 5, the data-signal Fig. 3 a that preserves according to step 4 draw out signal Phi 1 and the correlation results Fig. 3 b of signal Phi 2 when the different time difference, search signal Phi 1 and the signal Phi 2 correlations mistiming Δ τ between two signals when maximum at Fig. 3 b;

Step 6, according to formula: Vi=L/ Δ τ calculates the ion average velocity of directional plasma bundle, finding out Δ τ on Fig. 3 b is 18 μ s, obtaining L in step 2 is 33cm, Vi=18.3km/s then, Fig. 3 c is the continuous change profile figure of Vi in the 15 μ s that calculate according to formula Vi=L/ Δ τ.

Claims (2)

1. the relevant measurement method of directional plasma beam ion average velocity, finish the device that this method adopts following structure, this device is by steady-state plasma engine (1), positive bias power supply (2), oscillograph (3), first probe (4-1), second probe (4-2), first resistance (5-1), second resistance (5-2) and power supply (6) are formed, first probe (4-1) and second probe (4-2) are separately positioned in the plume district of steady-state plasma engine (1), the left and right sides central point of the upper surface of first probe (4-1) and second probe (4-2) all is positioned on the central axis up and down of steady-state plasma engine (1), first end of the output terminal of first probe (4-1) and first resistance (5-1) all is connected with the first input end of oscillograph (3), first end of the output terminal of second probe (4-2) and second resistance (5-2) all is connected with second input end of oscillograph (3), second end of first resistance (5-1), the power input of second end of second resistance (5-2) and oscillograph (3) all is connected with the positive terminal of positive bias power supply (2), the positive terminal of power supply (6) is connected with the positive terminal of steady-state plasma engine (1), and the negative pole end of power supply (6) and positive bias power supply (2) all is connected with the cathode compensation device (1-1) of steady-state plasma engine (1);

It is characterized in that method of the present invention is realized by following steps:

Step 1, start steady-state plasma engine (1) and be adjusted to the duty of stable discharging;

The voltage that step 2, adjustment positive bias power supply make first probe (4-1) and second probe (4-2) go up loading all is in the electronic current saturation region respectively;

Step 3, startup oscillograph (3) are also regulated displaying ratio and sweep time, make on the oscillograph (3) and can demonstrate oscillating signal clearly;

Step 4, record are also preserved steady-state plasma engine (1) first probe (4-1) and second probe (4-2) data-signal at one time section under steady-working state;

Step 5, according to the The data correlation method of preserving in the step 4 calculate first probe (4-1) and second probe (4-2) the mistiming Δ τ of the number of accepting and believing correlativity when the strongest;

Step 6, calculate the ion average velocity of directional plasma bundle according to formula Vi=L/ Δ τ, wherein Vi represents the ion average velocity of directional plasma bundle, L represents the distance between the left and right sides central point of upper surface of first probe (4-1) and second probe (4-2), the mistiming when Δ τ represents that two signal correlations are the strongest between the signal.

2. the relevant measurement method of directional plasma beam ion average velocity according to claim 1 is characterized in that it is realized by following steps:

Step 1, to start steady-state plasma engine (1) and be adjusted to sparking voltage Up be that 300V, anode gas supply flow are the duty of the stable discharging of 3mg/s;

Step 2, startup positive bias power supply (2), positive bias power supply (2) can adopt the adjustable D.C. regulated power supply of 0～100V, the output valve of adjusting positive bias power supply (2) is 40V, the distance that the left and right sides central point of first probe (4-1) upper surface is arranged on the central point up and down of steady-state plasma engine (1) is the 15cm place, and the distance that the left and right sides central point of second probe (4-2) upper surface is arranged on the central point up and down of steady-state plasma engine (1) is the 48cm place;

Step 3, startup oscillograph (3), oscillograph (3) can adopt Textronic TPS2024 type to isolate oscillograph, with the displaying ratio of oscillograph (3) be adjusted into 25 μ s/ lattice sweep time, make on the oscillograph (3) and can demonstrate oscillating signal clearly;

Step 4, preserve steady-state plasma engine (1) first probe (4-1) and second probe (4-2) data-signal at one time section under steady-working state and be designated as Fig. 3 a, signal Phi 1 among Fig. 3 a is the signal that first probe (4-1) obtains, and signal Phi 2 is the signal that second probe (4-2) obtains;

Step 5, the data-signal Fig. 3 a that preserves according to step 4 draw out signal Phi 1 and the correlation results Fig. 3 b of signal Phi 2 when the different time difference, search signal Phi 1 and signal Phi 2 correlations mistiming between two signals when maximum at Fig. 3 b: Δ τ;

Step 6, according to formula: Vi=L/ Δ τ calculates the ion average velocity of directional plasma bundle, finding out Δ τ on Fig. 3 b is 18 μ s, obtaining L in step 2 is 33cm, Vi=18.3km/s then, Fig. 3 c is the continuous change profile figure of Vi in the 15 μ s that calculate according to formula Vi=L/ Δ τ.

Images