document: Prior to assembling the miniature ADR, the mKCC MR heat switch could not be fully thermally characterised due to cryostat constraints. However, based on experiments and research conducted at MSSL on a range of tungsten heat switches, the thermal conductivity has been estimated. In Hills et al. [8], an equation is derived which allows the thermal conductivity (κ) below 6K to be calculated as a function of magnetic field (B) and temperature (T) (see Eq. (1)). To estimate the performance of the mKCC heat switch, the parameters in Eq. (1) have been taken from the measured thermal conductivity of another MSSL heat switch with the same 1.5mm square cross section, a free path length of 43cm and a RRR of 20,000; it has been observed from experiments conducted at MSSL that there is little change in the thermal performance for tungsten heat switches with a RRR between 20,000 and 32,000 (subject of a future publication) and therefore the performance of the 20,000 RRR heat switch has been assumed to be a good approximation. Fig. 5 gives the calculated thermal conductivity of the mKCC switch at 0, 1, 2 and 3T based on Eq. (1), where the constants b0, a1, a2, a3, a4 and n have the values 0.0328, 1.19×10−4, 3.57×10−6, 1.36, 0.000968 and 1.7 respectively. It should be noted that the calculated thermal conductivity of the mKCC switch presented in Fig. 5 has been validated by comparing the experimental results of the miniature ADR with modelled predictions (this is discussed in Section 3.3).(1)κ(T)=b0T2+1a1+a2T2T+Bna3T+a4T4
extractive_keyphrases: assembling the miniature adr b cryostat constraints magnetic field miniature adr mkcc heat switch mkcc mr heat switch mkcc switch mssl heat switch thermal conductivity thermally characterised thermal performance tungsten heat switches κ
abstractive_keyphrases: 20,000 rrr heat switch