Working principle of ordinary hollow cathode lamp
Date: 2014-09-24Read: 22
Apply a certain voltage to the two electrodes of the hollow cathode lamp to form an electric field. The inert gas filled in the lamp always ionizes a small number of atoms into free electrons and positive ions at room temperature. Under the action of an electric field, they accelerate towards the anode and cathode respectively. During the movement, they collide with other atoms, causing ionization of the atoms and releasing secondary electrons, increasing the number of electrons and positive ions. The discharge phenomenon is maintained, and the working voltage for maintaining the discharge is lower than that of the discharge voltage.
During the bombardment process, the inner surface of the cathode evaporates atoms due to heat, making it more prone to volatilization at low melting points. At the same time, the positive ion group with significant acceleration movement bombards the cathode, indicating that its atoms are sputtered out. The atoms on the inner surface of the cathode, which are sputtered and thermally evaporated, enter the hollow cathode space and undergo inelastic collisions with the accelerated positive ions, secondary electrons, and gas atoms during the discharge process, thereby obtaining energy and being excited to a high-energy state. When it returns to the ground state, it releases the obtained energy in the form of radiation characteristic wavelengths. When high-energy inelastic collisions occur, spark lines or ion lines are emitted; When low-energy inelastic collisions occur, atomic lines are emitted.
The higher the atomic density and collision frequency inside the hollow cathode, the greater the characteristic radiation intensity produced. When the atoms emitted by sputtering and thermal evaporation diffuse, the number of atoms escaping from the cathode and the corresponding atoms returning to the cathode, and the number of atoms deposited on the surface of the lamp shell wall or other parts reach equilibrium, the corresponding atomic density and discharge inside the hollow cathode remain stable.