Effect of gap length on effective field strength

A micro-channel plate (MCP) was used to measure the minute emission current within the range of 1×10^-19 A to 1×10^-14 A in a high vacuum (1.3×10^-5 Pa). By a Fowler-Nordheim plot, it is found that the effective field strength for initial electron emission is mostly constant between 10⁷ and 10⁸ V/cm under any gap length. The effective field strength is held constant between 10⁷ and 10 ⁸ V/cm, independent of the current under any gap length. With this result, a model which shows the choice of minute projection is suggested. In order to certify this model, an MCP phosphor-anode is used. As a result, it is found that the minute projections which emit electrons melt with heat and are chosen when the voltage rises