Validating the collision-dominated Child–Langmuir law for a dc discharge cathode sheath in an undergraduate laboratory

摘要

In this paper, we propose a simple method of observing the collision-dominatedudChild–Langmuir lawin the course of an undergraduate laboratorywork devotedudto studying the properties of gas discharges. To this end we employ the dc gasuddischarge whose properties are studied in sufficient detail. The undergraduateudlaboratory work itself is reduced to registering the voltage drop across theudelectrodes, the discharge current as well as the cathode sheath thickness. We can easily perform the measurements of all three quantities with sufficient accuracy in a laboratory equipped with vacuum pumps.