 The high-voltage rf spark source is the one that was used in commercial SSMS instruments due to its ability to ionize both conducting and non-conducting materials.Typically, samples are physically incorporated into two conductive electrodes between which an intermittent (1 MHz) high-voltage (50-100 kV using a Tesla transformer) electric spark is produced, ionizing the material at the tips of the pin-shaped electrodes.When the pulsed current is applied to the electrodes under ultra-high vacuum, a spark discharge plasma occurs in the spark gap in which ions are generated via electron impact.