KR101459633B1 - Apparatus for generating a high voltage atmospheric plasma using an external capacitor - Google Patents

Abstract

The purpose of the present invention is to provide a high voltage atmospheric plasma generating apparatus using external capacitors, which is capable of adjusting an applied voltage by applying n times higher voltage than the applied voltage to the plasma using n external capacitors. The high voltage atmospheric plasma generating apparatus comprises: a power supply unit which supplies power to generate plasma; a plasma generating unit which generates the plasma using the power of the power supply unit; a first switch and a fourth switch which are connected in series between the power supply unit and the plasma generating unit to control power supply during an operation of generating the plasma; a first capacitor and a second capacitor which are connected in parallel to contacts between the first and fourth switches, respectively, to perform charging and discharging and supply discharged energy to the plasma generating unit by control of the fourth switch; a second switch which is connected to one end of the second capacitor and controls charging of the first and second capacitors using the power supplied by the power supply unit while the first switch is turned on and the fourth switch is turned off; and a third switch which is connected in parallel to a contact between the second capacitor and the second switch and to a contact between the contact between the first and fourth switches and the first capacitor, and which controls discharging of the first and second capacitors which are connected to each other in series if the first and second switches are turned on and the fourth switch is turned on.

Description

BACKGROUND OF THE INVENTION Field of the Invention [0001] The present invention relates to an apparatus for generating a high-pressure atmospheric pressure plasma using an external capacitor,

The present invention relates to the generation of atmospheric pressure plasma, and more particularly to an apparatus and a method for generating atmospheric pressure plasma, in which a cathode of a plasma generating unit to which a gas is supplied is grounded and an anode is connected to n variable external capacitors, To a high-voltage, atmospheric-pressure plasma generator capable of controlling discharge energy using the plasma.

Atmospheric plasma is a technology used in various industrial fields such as semiconductor processing, medical equipment, surface treatment, environmental treatment, metal processing, cutting and the like. In particular, atmospheric plasma can be generated at atmospheric pressure, and thus it is widely applied to fields where the use of vacuum plasma is impossible, and the demand for vacuum plasma such as semiconductor processing and surface treatment is expanding to the industry.

Since atmospheric plasma does not use vacuum equipment, it is advantageous that the device cost is much lower than that of vacuum plasma equipment. However, since driving gas must be continuously injected and byproducts and gases generated in the plasma are directly exposed to the air, It has a disadvantage that it can not be applied to a process using a gas having a high cost and a high degree of haze. However, these disadvantages are also being complemented by the development of technology.

Atmospheric plasma can be classified into two categories: application using low temperature plasma and application using high temperature plasma from the viewpoint of plasma temperature. It can be used for substrate cleaning, surface treatment, semiconductor processing, medical equipment and the like using low temperature plasma, and can be applied to material synthesis, metal cutting, metal processing, etc. when using high temperature plasma.

To generate such a plasma, a DC power source, a sine wave, and a pulse voltage are used. It is generated as a unipolar type or bipolar type depending on the purpose or the surrounding environment, and frequency is several tens Hz to several GHz.

As described above, there is a problem in that the output of the plasma is not easily controlled as the discharge energy is determined by the structure of the apparatus or the power supply unit, such as the area, interval, discharge start voltage, . This requires precise control and a technique for discharging at a voltage higher than the discharge start voltage while controlling unintentional discharges during charging.

Therefore, there are various methods of generating the atmospheric plasma, but most of the methods are using DBD (Dielectric Barrier Discharge) or DC pulse power.

This is because the power source using sinusoidal AC is easy to manufacture and relatively inexpensive. However, there is a possibility that the form of power source may be changed according to the load of the plasma generation part, and the possibility of being affected by the L and C values This is big. In addition, the sinusoidal drive circuit once fabricated is not easily variable in frequency or requires a high production cost for frequency tuning.

In the case of a pulse power source, it is difficult to control voltage or current at the same power when the discharge energy is determined in the case of a sine wave or a pulse wave.

Patent Registration No. 10-1284735: Atmospheric-pressure plasma generator using external capacitor

Open Patent Publication No. 2010-0069263: DC pulsed atmospheric pressure glow plasma generator

Open Patent Application 2001-0103922: Device for generating glow discharge plasma at atmospheric pressure

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a high voltage atmospheric pressure plasma generator using an external capacitor capable of controlling an applied voltage by applying a voltage n times higher than an applied voltage to the plasma using n external capacitors, The purpose of the device is to provide.

Other objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.

According to another aspect of the present invention, there is provided a high-voltage atmospheric-pressure plasma generator using an external capacitor, comprising: a power supply unit for supplying a power source for plasma generation; a plasma generation unit for generating plasma using power of the power supply unit; First and fourth switches connected in series between the power supply unit and the plasma generating unit to control power supply during a plasma generating operation; and first and fourth switches connected in parallel between the first and fourth switches, A first capacitor connected in series to the other end of the second capacitor to turn on a first switch and a fourth switch to turn off; A second switch for controlling the charging of the first and second capacitors by using the power supplied from the power supply unit in the state And the first and second switches are connected in parallel to the contact between the second capacitor and the second switch and the contact between the first and fourth switches and the first capacitor so that the first and second switches are turned off and the fourth switch is turned on, And a third switch for controlling the discharge of the first and second capacitors connected to the first and second capacitors.

Preferably, at least one external capacitor composed of the first capacitor, the second, and the third switch is further added between the contacts of the first and fourth switches and the other end of the first capacitor.

And a GND switch connected in parallel between the fourth switch and the contact point of the plasma generating unit to generate the pulse voltage of the output voltage through the control after the discharge voltage of the first and second capacitors is applied to the plasma generating unit .

Preferably, the fourth switch is turned on only when the first and second capacitors are discharged.

Preferably, the fourth switch is operated later than the third switch at the time of discharging.

Preferably, the first to fourth switches are transistors.

Preferably, the second switch is operated later than the first switch when the first and second capacitors are charged.

And a diode between the first switch and the fourth switch.

As described above, the high-voltage atmospheric-pressure plasma generator using the external capacitor according to the present invention can generate a variety of plasmas as a single device by generating plasma at normal pressure. In addition, it is possible to generate plasma from a low-temperature glow plasma close to room temperature to a high-temperature plasma close to several thousand arc or more, and can exhibit various plasma characteristics by varying discharge current and output voltage at the same power consumption.

Therefore, the present invention can be applied to various applications such as changes in properties of materials, surface treatment, medical field, and material processing.

FIG. 1A is a conceptual diagram illustrating a high-voltage atmospheric-pressure plasma generator using an external capacitor according to an embodiment of the present invention.
1B and 1C are conceptual diagrams showing the configuration of a circuit when the plasma generating apparatus of FIG. 1A is charged and discharged, respectively. FIG.
Fig. 2 is a diagram showing the on / off timing of the first switch to the fourth switch in Fig. 1a
3 is a conceptual diagram illustrating a plasma generator capable of outputting a voltage n times higher than an applied voltage using n external capacitors according to another embodiment of the present invention.
4 is a graph showing current and voltage waveforms measured at the time of plasma generation using a high-voltage atmospheric-pressure plasma generator according to an embodiment of the present invention;

Other objects, features and advantages of the present invention will become apparent from the detailed description of the embodiments with reference to the accompanying drawings.

A preferred embodiment of a high-voltage atmospheric-pressure plasma generator using an external capacitor according to the present invention will now be described with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. It is provided to let you know. Therefore, the embodiments described in the present specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and are not intended to represent all of the technical ideas of the present invention. Therefore, various equivalents It should be understood that water and variations may be present.

FIG. 1A is a conceptual diagram illustrating a high-voltage atmospheric-pressure plasma generator using an external capacitor according to an embodiment of the present invention.

As shown in FIG. 1A, a high-voltage atmospheric-pressure plasma generator using an external capacitor includes a power supply unit (DC high voltage) for supplying a power for generating plasma, a plasma generator for generating plasma using power of the power supply unit, First and fourth switches (Switches 1 and 4) connected in series between the power supply unit and the plasma generating unit to control power supply during a plasma generating operation, first and fourth switches (Switch 1 and 4) First and second capacitors C1 and C2 connected in parallel to each other for charging and discharging and supplying discharge energy to the plasma generator under the control of the fourth switch 4, The first switch Switch 1 is turned on in series with the other terminal of the first switch C2 and the first and second switches 2 and 3 are turned on using the power supplied from the power supply unit in a state that the fourth switch 4 is turned off, A second switch Switch 2 for controlling the charging of the capacitors C1 and C2 and a contact between the contacts of the second capacitor C2 and the second switch Switch 2 and the contact between the first and fourth switches Switch 1 and 4 The first and second switches (Switch 1 and 2) are turned off and the fourth switch (Switch 4) is turned on and connected in series to each other, And a third switch (Switch 3) for controlling the discharge of the two capacitors C1 and C2. A diode is formed between the first switch (Switch 1) and the fourth switch (Switch 4).

The diode is a one-way switch that limits the current direction during charging and discharging. The use of diodes also reduces the effect of internal capacitors present in the device and reduces the cost of the drive circuit.

The high voltage atmospheric pressure plasma generator using the external capacitor will be described with reference to FIG. 1A. In the state where the voltage V ₀ for generating plasma is applied to the DC high voltage, the first switch (Switch 1) and the second switch If the second operation switch (switch 2),, the voltage of ₀ V to the first capacitor (C1) and second capacitor (C2) is charged, such as that shown in Figure 1b.

When the third switch (Switch 3) and the fourth switch (Switch 4) are operated while the first switch (Switch 1) and the second switch (Switch 2) are turned off after the charging, As shown in FIG. 1C, the capacitors C1 and C2 are connected in series, and a voltage of 2V ₀ is output to the plasma generator.

When a voltage of 2V ₀ is applied to the plasma generator, if the GND switch is operated as needed, a pulse waveform can be formed as the output voltage falls to the GND voltage.

At this time, when the voltage of V ₀ is higher than the discharge start voltage, a DC discharge upon charging is generated as shown in FIG. If this unintentional discharge occurs, both the power supply part and the plasma generating part may be seriously damaged. A fourth switch (Switch 4) was introduced to prevent such damage. That is, if the fourth switch (Switch 4) is turned on only during the discharge, damage of the plasma generating device can be prevented.

FIG. 2 is a diagram showing the on / off timing of the first switch to the fourth switch in FIG. 1A. In FIG. 2, the vertical axis indicates voltage, which is on when the voltage is high, to be.

As shown in Fig. 2, the elements of the first to fourth switches constituted in Fig. 1A can be controlled in the region of several tens of ns by using transistors.

That is, the second switch (Switch 2) is operated 300 ns later than the first switch (Switch 1) during the charging so as not to be simultaneously charged. This allows the overshoot to be reduced by adjusting the turn-on timing of the switch as the di / dt increases and the overshoot (ringing) may become large when charged at the same time.

In addition, the fourth switch (Switch 4) is operated 100 ns later than the third switch (Switch 3) to prevent the DC discharge from occurring during charging.

3 is a conceptual diagram illustrating a plasma generator capable of outputting a voltage n times higher than an applied voltage using n external capacitors according to another embodiment of the present invention.

As shown in Fig. 3, at least one external capacitor constituted by the first capacitor, the second and the third switch shown in Fig. 1 is connected between the contacts of the first and fourth switches and the other end of the first capacitor As shown in FIG.

If the external capacitor shown in FIG. 1A is composed of n capacitors using a switching device, the voltage applied to the plasma generating part can be increased to n times.

Therefore, the discharge voltage can be applied at a higher voltage than the discharge start. That is, when the discharge starting voltage is 200V, if the triple back pressure circuit is used, the voltage of 200V can be tripled and the discharge can be induced to a voltage of 600V. Accordingly, when the battery is charged at 300 V, a discharge may occur when the battery is charged.

The fact that the applied voltage can be driven to a voltage higher than the discharge start voltage means that the discharge voltage and the discharge current can be variously adjusted, which means that various plasma characteristics can be exhibited.

For example, even if the same discharge energy (Q = CV) is consumed, it can be configured with a low capacitor capacity - a high voltage or a high capacitor capacity - a low voltage.

In this case, the discharge current varies, so the density and temperature of the plasma change. It is also possible to vary the discharge current by varying the discharge voltage at the same capacitor capacitance, which also changes the plasma characteristics. Note that the capacitance of this device's capacitor is 100pF to 100μF.

In addition, since the plasma generating apparatus can generate micro plasma at a high voltage, it is possible to drive plasma in various gases. In other words, it can be used for inert gases such as He, Ne, Ar, Kr, and Xe, as well as for general gases, process gases such as carbon dioxide, nitrogen, or CF ₄ , such as Fluorocarbon Gas and SiF ₄ . Do. It can also be used in mixed gas with various gases.

FIG. 4 is a graph showing current and voltage waveforms measured at the time of plasma generation using a high-voltage atmospheric-pressure plasma generator according to an embodiment of the present invention. In FIG. 4, two external capacitors are used to increase the voltage twice, Both capacities are 22pF and the input voltage is 250V.

Therefore, as shown in FIG. 4, a voltage (blue solid line) backed up to 500 V, which is twice the input voltage, was output to the plasma generating section, and microplasma was generated by this voltage.

The orange dotted line shows the current waveform instantaneously rising up to 15A, discharge current was about 500ns, and the discharge was stopped and stopped with the current. That is, it can be seen that the discharge is stopped. In this case, the discharge energy consumed per pulse is 370 μJ, which is a 7.4 W micro-plasma.

As described above, the applied voltage can be adjusted by applying a voltage n times higher than the applied voltage to the plasma generating portion using n external capacitors. In addition, since the capacitance of the external capacitor can be changed, the applied voltage and the discharge current can be controlled at the same power consumption, and the plasma characteristics can be changed. Also, by controlling the external capacitor, discharge can be controlled from glow discharge to arc discharge.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It will be apparent to those skilled in the art that various modifications may be made without departing from the scope of the present invention. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

Claims (10)

A power supply unit for supplying power for plasma generation,
A plasma generator for generating plasma using the power of the power supply;
First and fourth switches connected in series between the power supply unit and the plasma generation unit to control power supply during a plasma generation operation,
First and second capacitors connected in parallel between the first and fourth switches for charging and discharging and supplying discharge energy to the plasma generator under the control of the fourth switch;
A second switch connected in series to the other end of the second capacitor to turn on the first switch and to control the charging of the first and second capacitors by using a power supplied from the power supply unit in a state where the fourth switch is turned off,
The first and second switches are connected in parallel to the contact between the second capacitor and the second switch and the contact between the first and fourth switches and the first capacitor so that the first and second switches are turned off and the fourth switch is turned on, And a third switch for controlling discharge of the first and second capacitors. The method according to claim 1,
Wherein at least one external capacitor composed of the first capacitor, the second, and the third switch is further added between the contacts of the first and fourth switches and the other end of the first capacitor. Atmospheric pressure plasma generator. The method according to claim 1,
And a GND switch connected in parallel between the fourth switch and the contact point of the plasma generating unit to generate a pulse having an output voltage through control after a discharge voltage of the first and second capacitors is applied to the plasma generating unit, A high voltage atmospheric pressure plasma generator using external capacitors. The method according to claim 1,
And the fourth switch is turned on only when discharging the first and second capacitors. 5. The method of claim 4,
Wherein the fourth switch is operated later than the third switch when discharging the high voltage atmospheric pressure plasma. 6. The method of claim 5,
And the fourth switch is 100 ns later than the third switch. The method according to claim 1,
Wherein the first switch to the fourth switch are constituted by transistors. ≪ RTI ID = 0.0 > 11. < / RTI > The method according to claim 1,
And the second switch is operated later than the first switch when the first and second capacitors are charged. 9. The method of claim 8,
Wherein the second switch is operated 300 ns later than the first switch. The method according to claim 1,
Further comprising a diode between the first switch and the fourth switch. ≪ RTI ID = 0.0 > [10] < / RTI >

Images