 
 <prompt> Hot cathode gauges fit measure vacuum pressures of wetin? Given di last question, write one context wey contain di answer. E fit be 1 - 20 sentences. Context: <response>: Ion gauges dey use for ultrahigh vacuum. Dem dey come in two types: hot cathode and cold cathode. For hot cathode version, electrically heated filament dey produce electron beam. The electrons dey waka through the gauge and ionize gas molecules around dem. The ions wey result dey collect for negative electrode. The current dey depend on the number of ions, wey depend on the pressure for the gauge. Hot cathode gauges dey accurate from 10−3 torr to 10−10 torr. The principle behind cold cathode version na the same, except say electrons dey produce for discharge wey high voltage electrical discharge create. Cold cathode gauges dey accurate from 10−2 torr to 10−9 torr. Ionization gauge calibration dey very sensitive to construction geometry, chemical composition of gases wey dem dey measure, corrosion and surface deposits. Their calibration fit spoil if dem activate am for atmospheric pressure or low vacuum. The composition of gases for high vacuums fit no dey predictable, so mass spectrometer gats dey use together with the ionization gauge for accurate measurement. 