[1] He received his PhD from the University of Leiden in 1923,[2] and studied low pressure gas discharges at the Philips Laboratory in Eindhoven, developing new electron tubes during World War II.

Penning received his PhD on June 25, 1923, with a dissertation entitled Metingen over isopyknen van gassen bij lage temperaturen (Measurements on isometric density lines of gases at low temperatures).

[2] His father Louwrens Penning, was a popular novelist in the Dutch literary community; most known for romanticizing the Anglo-Boer War.

Gilles Holst, former assistant to Heike Kamerlingh Onnes, and head of the Philips Natuurkundig Laboratorium (NatLab), tasked Penning with continuing research on gas discharge phenomena to develop new lamps.

In 1926, Penning observed that electrons under direct voltage current in low-pressure mercury discharges reach high velocities due to high-frequency oscillations in the gas.

[7] The Penning effect, as it is often called, describes an ionization chain reaction caused by high energy collision between excited inert gas (i.g.

These collisions cause the release of electrons; which can interact with other stable noble gas molecules to create more meta-stables, resulting in more ionizing reactions.

In his first attempt to measure the energy current, Penning used a triode ion gauge system with a linear electron flight path.

Dehmelt got inspiration from the vacuum gauge built by Penning where a current through a discharge tube in a magnetic field is proportional to the pressure.