Table 1.

Estimation of the characteristic lengthscale $\ell$, thermal diffusivity α and thermal timescale $\tau ={\ell }^2/\alpha$. Values evaluated at 100 K, for a aluminium vial, helium filled gap and copper TESU.

	$\ell$ [m]	α [m2s−1]	τ [s]
vial wall δ	2 × 10−4	1 × 10−4	4 × 10−4
gap d	4 × 10−4	2 × 10−5	8 × 10−3
TESU wall W	1 × 10−2	1.5 × 10−4	6 × 10−1