电弧焊基础（Arc welding foundation）.docVIP

电弧焊基础（Arc welding foundation） A, 1 in the cathode conductive characteristics of cathode functions: accept positive ions and emission cathode electronic institutions: the thermionic emission of cathode surface, field emission, thermal ionization collision local plasma emission cathode. Hot cathode (tungsten, carbon, etc.) : hot emission cold cathode (iron, aluminum, etc.) : electric field emission collision emission plasma caused the thermal power to leave. The electric conduction characteristic of the arc column is disorganized and the average kinetic energy is increased, resulting in high temperature. The molecules, the atoms, will generate a thermoelectric shock, forming a plasma. The n arc column is electrically neutral (the unit volume is positive and negative with point particles The charged particles are directed to move and are essentially free from the repulsive action of the space electric field, so they can transmit a large current under low voltage conditions. N arc column length is arc length, arc column length Voltage drop becomes an arc field strength. The intensity of electric field in the arc column is low: usually only 5 ~ 10v/cm. The role of anodes in the conductive characteristic of the 3 anode area: to accept the electron and provide the positive ion to the arc column. The production mechanism of positive ions:? Ionization under the action of the anode field: in the case of small current, the thermal power is difficult to get out. Forming an anode pressure drop? Electron kinetic energy? Collision ionization? Until the anode voltage is stable. ? Thermoelectric discharges in anodized zone: in the case of large current, the anode pressure drop is approximately zero, at which point the metal evaporates due to high electrode temperature. Thermal ionization? Does the current not form an anode when it is large enough? The anode pressure drop is also related to the electrode material characteristics, the thermal conductivity is good and the anode pressur