Continuous Loading of an Electrostatic Trap for Polar Molecules

A continuously operated electrostatic trap for polar molecules is demonstrated. The trap has a volume of ≈0.6 cm³ and holds molecules with a positive Stark shift. With deuterated ammonia from a quadrupole velocity filter, a trap density of ≈10⁸ cm^-3 is achieved with an average lifetime of 130 ms and a motional temperature of ≈300 mK. The trap offers good starting conditions for high-precision measurements, and can be used as a first stage in cooling schemes for molecules and as a ``reaction vessel'' in cold chemistry.