helium discharge ionisation detection pulsed discharge helium ionisation detection pulsed discharge helium ionization detection PDHID pulse-discharge helium ionisation detection pulse-discharge helium ionization detection A detection method that is sensitive to small gas molecules (e.g. O2, N2, CO2). A low-power, pulsed DC discharge is used to ionise the sample (which is held in He carrier gas). The resulting electrons are focused toward a collector electrode and the current is measured. CHMO:0001725