28-needle thruster crown

Close-up of the 1-cm-diameter porous tungsten crown used in the IFM Nano Thruster. The IFM nano thruster is a miniaturised ion thruster – with an electric field applied to accelerate electrically-charged atoms (known as ions) to produce thrust – that uses liquid indium as its propellant. The liquid metal flows by capillary action inside the porous tungsten crown’s 28 needles, resting at tiny holes in their razor-sharp tips. It is held in place there by surface tension, until an electric field is generated. This causes tiny cones to form in the liquid metal, which have positive ions shooting from their tips to create thrust.