Final published version
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Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - A high throughput facility for the RF characterisation of planar superconducting thin films
AU - Seal, D
AU - Malyshev, O B
AU - Goudket, P
AU - Sian, T
AU - Gurran, L
AU - Valizadeh, R
AU - Marks, H
AU - Pattalwar, S
AU - Pattalwar, N
AU - Pira, C
AU - Chyhyrynets, E
AU - Burt, G
PY - 2024/11/1
Y1 - 2024/11/1
N2 - Accelerator laboratories worldwide are researching copper radio frequency (RF) cavities coated with superconducting thin films to exceed the limits of bulk niobium. The development and RF testing of thin films on small planar samples is vital before cavity depositions. A team at Daresbury Laboratory have developed a cost-effective facility using a novel 7.8 GHz Choke Cavity for the RF characterisation of planar samples. RF chokes ensure that no electrical contact is required between the sample and the cavity. The main advantages are: a simple sample design (90–130 mm diameter disk with no sample-cavity welding) and easy operation using a LHe-free cryostat. This enables high sample throughput, with up to 3 sample tests per week, making the facility suitable for quick, systematic scanning of deposition parameters. With the sample thermally and physically isolated from the test cavity, it is possible to measure the average surface resistance, Rs, directly using an RF-DC compensation method. Facility commissioning has been performed with bulk and thin film niobium samples. These tests have demonstrated the ability to measure Rs at temperatures in the range 4–20 K and sample peak magnetic fields up to 3 mT. At present, the minimum resolvable Rs is 0.5 μΩ with typical uncertainties of 9%–15%. The design, operation and commissioning of this facility is reported in this paper.
AB - Accelerator laboratories worldwide are researching copper radio frequency (RF) cavities coated with superconducting thin films to exceed the limits of bulk niobium. The development and RF testing of thin films on small planar samples is vital before cavity depositions. A team at Daresbury Laboratory have developed a cost-effective facility using a novel 7.8 GHz Choke Cavity for the RF characterisation of planar samples. RF chokes ensure that no electrical contact is required between the sample and the cavity. The main advantages are: a simple sample design (90–130 mm diameter disk with no sample-cavity welding) and easy operation using a LHe-free cryostat. This enables high sample throughput, with up to 3 sample tests per week, making the facility suitable for quick, systematic scanning of deposition parameters. With the sample thermally and physically isolated from the test cavity, it is possible to measure the average surface resistance, Rs, directly using an RF-DC compensation method. Facility commissioning has been performed with bulk and thin film niobium samples. These tests have demonstrated the ability to measure Rs at temperatures in the range 4–20 K and sample peak magnetic fields up to 3 mT. At present, the minimum resolvable Rs is 0.5 μΩ with typical uncertainties of 9%–15%. The design, operation and commissioning of this facility is reported in this paper.
KW - superconducting radio frequency
KW - choke cavity
KW - thin film
KW - niobium
KW - superconductivity
U2 - 10.1088/1361-6668/ad7643
DO - 10.1088/1361-6668/ad7643
M3 - Journal article
VL - 37
JO - Superconductor Science and Technology
JF - Superconductor Science and Technology
SN - 0953-2048
IS - 11
M1 - 115012
ER -