an ionization vacuum gauge includes a linear cathode , an anode , and an ion collector . the linear cathode , the anode , and the ion collector are concentrically aligned and arranged from center to outer , in that order . the linear cathode includes a linear base and a field emission film deposited coating on the linear base . the ionization vacuum gauge with low power consumption can be used in a high vacuum system and / or some special vacuum system that is sensitive to heat and light . such a gauge can be used to determine , simply yet accurately , pressures at relatively high vacuum levels .