The function of hollow cathode lamps and hollow cathode lamps

      

　　Speaking ofHollow cathode lampPresumably many people don't know what kind of lamp this is. In fact, the hollow cathode lamp is a product proposed by A. Walsh in 1955 to solve the actual measurement problem of atomic absorption spectrometry. It is a special form of low-voltage glow discharge ray light source. The sharp line light emitted by this light meets the conditions of atomic absorption spectrometry. Therefore, the original function of the hollow cathode lamp is to solve the measurement problem of atomic absorption spectrometry and develop the product. Let's take a look at what the functions of the hollow cathode lamp are!

　　Hollow cathode lamp structure and materials

　　The structure of a hollow cathode lamp is composed of a cathode, an anode, and a shielding layer. The cathode is mostly pure metal or alloy. For some precious metals, it is made into a thin sheet and lined on the support electrode. The cathode is in the shape of an empty bucket in the middle, hence the name of the hollow cathode lamp. The anode is a tungsten rod welded with a tantalum sheet or titanium wire, because the tantalum sheet or titanium wire has a suction effect and can absorb a small amount of harmful gases (such as H2) at high temperatures. The shielding layer is provided between the cathode and the anode to prevent the breakdown of the cathode.

　　The function of hollow cathode lamp

　　1. Hollow cathode lamps are a special form of low-pressure gas discharge light source. The discharge is concentrated in the cathode cavity. When a voltage of 200V-500V is applied between the two poles, a glow discharge is generated. Under the action of an electric field, electrons collide with the carrier gas atoms on their way to the anode and ionize them, releasing secondary electrons, which increases the number of electrons and positive ions to maintain discharge. Positive ions obtain kinetic energy from the electric field. If the kinetic energy of positive ions is sufficient to overcome the lattice energy on the surface of the metal cathode, when they hit the cathode surface, atoms can be sputtered out of the lattice, so hollow cathode lamps have the effect of sputtering atoms out.

　　2. The cathode also causes the thermal evaporation of the elements on the cathode surface during the heating process. The sputtered and evaporated atoms enter the cavity and are excited by the second type of collision with electrons, atoms, ions, etc., emitting the characteristic resonance radiation of the corresponding elements. At the same time, the spectral lines emitted by the hollow cathode lamp also include lines such as internal inflation, cathode materials, and impurity elements.

　　Precautions for the use of hollow cathode lamps

　　When using the hollow cathode lamp, pay attention that the polarity cannot be reversed. In order to stabilize the luminous intensity of the lamp, preheat it for 10-30 minutes under the working current. If the lamp is not used for a long time, it should be ignited regularly. Generally, it is preheated for one hour under the working current. If it is put on hold for a long time, there are impurities in the lamp. You can use the reverse connection and gas removal method. The reverse electrode is lit with a high current for 30 minutes. Because the hollow cathode lamp is a special form of low-pressure gas discharge light source, it must be carried out in accordance with the specifications during operation to avoid the influence of anti cathode. To buy the hollow cathode lamp, you can go to the national standard product network. The national standard product network sells atomic absorption hollow cathode lamps tested by various instrument manufacturers. For related products