Under the condition of normal air 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 and generate self-excited conduction, which is called spark discharge.The collision ionization generated by this discharge process is carried out along the narrow and tortuous light-emitting channel, accompanied by sparks and violent sound.[1]
Chinese name
Spark discharge
Foreign name
spark discharge
Nature
A form of gas discharge
Features
It is named because the power generation channel looks like sparks
Discipline
Physics
Application
Spectral analysis, igniter of internal combustion engine, etc
Whenhigh-voltage power supplyWhen the power of is not too high, the gas between high-voltage electrodes isbreakdown, flash andPopping soundGas ofdischargePhenomenon.Under normal air pressure, whencurvatureWhen high voltage is applied between small cold electrodes, if the power supplied by the power supply is not large, spark discharge will occur. During spark discharge, collision ionization does not occur in the entire area between electrodes, but only along narrow and zigzag light-emitting channels, accompanied by a burst sound.Due to the sudden change frominsulatorIt becomes a good conductor, the current increases sharply, but the power supply is not enough, so the voltage drops, the discharge is temporarily extinguished, and it is discharged again when the voltage recovers.So spark discharge hasInterstitial。thunderIt is the large-scale spark discharge in nature.Spark discharge can be used for metal processing and drilling small holes.Spark gap can be used for protectionElectrical equipmentSo that it will not be damaged when struck by lightning.
stayPotential differenceGenerated between high positive and negative charged areasgas discharge Phenomenon.be used forGluingSurface treatment to improve bonding strength.It is mainly used for surface treatment of difficult to stick plastic, metal and other materials.stayAtmospheric pressureOr a form of gas discharge under high pressure, named after the power generation channel looks like a spark.
Spark discharge principle
Announce
edit
Flash and sound instantaneous gas discharge occurs between positive and negative charged areas with high potential difference.In the discharge space, the gas molecules are ionized, and the gas heats rapidly and violently, emitting flash and sound.The path through which the discharge channel passes and its luminous and conductive properties depend on the shape and size of the positive and negative charged areas, the potential difference between them, and the nature and pressure of the gas.Because the voltage between the two poles is very high during spark discharge, but the power supply is not large, once the discharge occurs, the current intensity increases sharply, and the voltage decreases, causing the discharge to be temporarily extinguished. The discharge will not be conducted until the voltage recovers.Therefore, the spark discharge is intermittent.Lightning is a large-scale spark discharge phenomenon in nature.In high voltage devices, sparks may appear between parts with poor contact.This phenomenon consumes energy, damages the device and is easy to cause danger.
influence factor
Announce
edit
As the breakdown voltage causing spark discharge depends on the electrode shape and the distance between them when other conditions remain unchanged, in high-voltage engineering, unknown high voltage values are often measured by the distance between electrodes of a certain shape when spark discharge occurs (called spark gap).The following table shows the relationship between the spark gap (mm) of several electrode shapes and the voltage.
Voltage/V
Two-point electrode
5mm diameter
Two spherical electrodes of
Two plate electrodes
twenty thousand
forty thousand
one hundred thousand
two hundred thousand
three hundred thousand
fifteen point five
forty-five point five
two hundred
four hundred and ten
six hundred
five point eight
thirteen
forty-five
two hundred and sixty-two
five hundred and thirty
six point one
thirteen point seven
thirty-six point five
seventy-five point three
one hundred and fourteen
Spark discharge hazard
Announce
edit
becausestatic electricitySparks ignite certain flammable objects and cause explosion.In the dark night, when people take off their nylon and woolen clothes, they will make sparks and "beep" sound, which is basically harmless to the human body.But on the operating table, the electric spark will cause the explosion of anesthetic and hurt doctors and patients;In coal minesgas explosion, which will lead to death and injury of workers and abandonment of the mine.In a word, the electrostatic hazard is caused by the use of electricity and electrostatic sparks. The most serious electrostatic hazardelectrostatic discharge Cause fire and explosion of combustibles.People often say that,Nip in the budThe measures to prevent static electricity are generally to reduce the flow rate and flowPower onStrong process links, equipment and materials with less electrification, etc.The simplest and most reliable way is to ground the equipment with wires, which can lead the charge to the ground and avoid the accumulation of static electricity.Careful passengers will probably find that there aredischargeWhen the aircraft lands, in order to prevent passengers from getting electric shock when getting off the aircraft, most aircraft landing gears use special grounding tires or grounding wires to discharge the static charges generated by the aircraft in the air.We often seeOil tankThere is an iron chain at the rear of the car, which is the grounding wire of the car.Properly increase the humidity of the working environment so that the charge can be discharged at any time, which can also be effectively eliminatedstatic electricity。This is why it is not easy to do static electricity test in wet weather.The antistatic agent researched by researchers can eliminateinsulatorInternal static electricity.
Utilization of spark discharge
Announce
edit
Main applications: ① Spectral analysis ②Igniter of internal combustion engine. ③MetalEDM: onelectrolyte solutionThe metal workpiece is corroded by spark discharge to form a surface corresponding to the shape of the tool electrode (this processing method can pierce, carve and make various surface cavities on very hard metal). ④High voltage value measurement: because the minimum voltage that causes spark discharge (i.e. breakdown voltage, see "gas discharge") is related to the shape of electrodes and the distance between electrodes, unknown high voltage values are often measured by measuring the distance between electrodes of a certain shape when spark discharge occurs in high voltage engineering.
The starter of fluorescent lamp also uses sparkdischargePrinciple.Closed fluorescent lampKeyThe voltage makesneonDischarge, the heat generated by discharge makes the moving piece in the glass tube expand and connect with the stationary piece.Flashes and clicks are emitted in the process.When the waiting piece is disconnected from the stationary piece, the high voltage will discharge the mercury vapor in the lamp tube and the fluorescent lamp will emit light.[2]
