What are the differences and connections between glow, corona, spark and arc discharge?

1. Glow discharge refers to the gas discharge phenomenon that glows in low-pressure gas, that is, the self-sustaining discharge (self-excited conduction) phenomenon in rare gas;

2. Corona discharge refers to the local self-sustaining discharge of gas medium in uneven electric field, which is the most common form of gas discharge;

3. Spark discharge means that under the condition of low pressure and low power supply, if a high voltage is applied between two cold electrodes with small curvature, the gas between the electrodes will be broken down by a strong electric field, resulting in self-excited conduction;

4. Arc discharge refers to the discharge phenomenon that the arc emits white light and produces high-temperature gas. No matter in rare gas, metal vapor or atmosphere, when the power supply is high and can provide enough current (several amperes to several tens of amperes), the gas will decompose, give off strong brilliance and produce high temperature (thousands to tens of thousands of degrees). This gas self-sustaining discharge is arc discharge.

Second, the principle and mechanism are different.

1. glow discharge is a low-voltage discharge phenomenon, and the working pressure is generally lower than 10 mbar. Its basic structure is to put two parallel electrode plates in a closed container. Neutral atoms or molecules are excited by the generated electrons, and the excited particles will release energy in the form of light when they fall from the excited state to the ground state.

2. The formation mechanism of corona discharge is different due to the different polarity of tip electrode, which is mainly caused by the different accumulation and distribution of space charges during corona discharge.

Under the action of DC voltage, both negative corona and positive corona gather space charges near the tip electrode.

In negative corona, when electrons cause collision ionization, they are driven to the space far away from the tip electrode and form negative ions, while positive ions gather near the electrode surface. When the electric field continues to strengthen, positive ions are sucked into the electrode, and pulse corona current appears at this time, and negative ions diffuse into the gap space.

After that, repeat the next ionization and charged particle movement process. This cycle produces corona current in the form of many pulses.

3. The formation mechanism of spark discharge is the instantaneous gas discharge phenomenon accompanied by flash and sound between the positive and negative charged areas with high potential difference. In the discharge space, gas molecules ionize, and the gas heats up rapidly and violently, giving off flashes and sounds. Spark discharge is intermittent. Lightning is a large-scale spark discharge phenomenon in nature.

4. The mechanism of arc discharge is that the two electrodes are separated immediately after contact, and the surface temperature of cathode rises sharply due to short circuit heating, resulting in thermionic emission. Thermionic emission greatly increases the impact ionization and secondary electron emission of the cathode, so that the gas between the two electrodes has good conductivity.

Extended data:

Application of glow discharge;

The main application of glow discharge is to use its luminous effect (such as neon lamp and fluorescent lamp) and the voltage stabilizing effect of normal glow discharge (such as neon lamp regulator). He-Ne laser is made by using the characteristics of laser generated by glow discharge positive column area.

In recent years, glow discharge has been widely used in sewage treatment, sterilization and disinfection, surface modification of polymer materials, ion source of analytical instruments and other fields.

Because of its characteristics, glow power generation is applied to emission spectrum analysis and used as an excitation light source for gas analysis and difficult-to-excite element analysis. Connect a flat plate electrode at both ends of the glass tube, fill it with inert gas, and add a DC voltage of several hundred volts, and glow discharge will occur in the tube, and its current is 10-4 ~ 10-2a.

The discharge form is related to gas properties, pressure, discharge tube size, electrode material, shape and distance. When it is applied to the emission spectrum, the concentration of lead can be detected.

Baidu encyclopedia-glow discharge

Baidu encyclopedia-corona discharge

Baidu encyclopedia-spark discharge

Baidu encyclopedia-arc discharge