Reduction of vibrational noise from continuously filled 1 K pots

Abstract

We have examined the vibrational noise originating from 1.3 K pumped helium chambers ͑1 K pots͒ that are continuously filled from the 4.2 K bath through an impedance. The noise can be largely eliminated by either heating the pot or by heating the impedance directly. Noise in 1 K pots has detrimental consequences for the operation of audio frequency torsional oscillators and for high precision thermometry.

A stiff scanning tunneling microscopy head for measurement at low temperatures and in high magnetic fields

“…19 Operation of the 1 K pot does not affect the hold time of the dewar perceptively. To avoid additional noise production from the operation of the 1 K pot, [20][21][22] we have implemented pre-cooling measures to ensure that incoming LHe is cooled -ideally below the λ-point at 2.18 K -prior to entering the 1 K pot. The capillary that feeds the 1 K pot from the helium bath is ∼1 m long and has an inner diameter of 100 μm.…”

Noise and Correlation Study of Quantum Hall Devices

“…Noise measurements at the base temperature revealed strong excess noise with many sharp lines in the spectrum, which is attributed to so-called 1-K pot oscillations [11]- [13]. We explicitly point to this source of noise because of its possible relevance to other QHR measurements.…”

Prospects for terrestrial equivalence principle tests with a cryogenic torsion pendulum

“…We hope that it is linked to the deliberately very large quadrupole moment of the G pendulum, through couplings to time-varying ambient gravity gradients and/or couplings between swing and torsional oscillation modes-in which case this excess noise will be largely absent with the highly symmetric pendulum used in an EP test. Other possibilities include noise associated with the flow of helium into the 2 K pot through the capillary tube (for which there are cures [12]), and noise linked to vertical bounce mode oscillations of the pendulum, which may be reduced with appropriate damping [13]. The observed noise does not appear to be particularly correlated to ambient microseismic noise monitored by a seismometer.…”