Question

the phenomenon in which the end of the discharge tube the opposite to Cathode start glowing is --------​

Answer 1

Answer:

Explanation:

The ИН-13 (or IN-13) is part of the family of cold cathode gas discharge tubes. Unlike their big cousins, the thermionic tubes, most types of cold cathode tubes do not utilise a glowing-hot cathode. What is more, cold cathode tubes in general do not operate under a high vacuum but are filled with an inert gas at a pressure much below atmospheric.

To summarise its operation, we can’t think of a more appropriate way than an I-V plot of a simplified cold cathode tube setup (figure 1).

Figure 1: Simplified tube test setup (left) and corresponding characteristic I-V plot (right). The Townsend avalanche process is indicated inside the cold cathode tube.

Figure 1: Simplified tube test setup (left) and corresponding characteristic I-V plot (right).

The Townsend avalanche process is indicated inside the cold cathode tube.

In the setup a sealed glass tube is filled with Neon gas. A metallic plate is positioned at each end of the tube and then connected to a power supply. The plate connected to the positive terminal of the power supply is the anode, while that connected to the negative terminal is the cathode. The voltage across the tube is increased while the current is measured and plotted.

The gas will normally behave as an insulator thus preventing any current from flowing. However, in practice cosmic radiation (highly energetic subatomic particles) will intermittently ionise Neon atoms, generating negatively charged electrons (e-) and positively charged Neon ions (Ne+). If a small voltage is applied across the tube, the electrons will be attracted to the anode and the ions to the cathode. Most particles will not reach the plates due to collisions with other particles, or neutralisation from particles with an opposite charge. As the voltage is increased, the percentage of particles reaching the plates increases, leading to an increase in current. Eventually, a saturation point is reached where all particles reach the plates (VSat of figure 1).