Quench Detection System for TF Coil-Test Campaigns of SST-1

We investigate whether by synthesising superconductors that are tuned to a topological, node-reconstruction transition point we could create superconducting wires that are intrinsically resilient to quenches. Recent work shows that the exponent characterising the temperature dependence of the specific heat of a nodal superconductor is lowered over a region of the phase diagram near topological transitions where nodal lines form or reconnect. Our idea is that the resulting enhancement of the low-temperature specific heat could have potential application in the prevention of superconductor quenches. We perform numerical simulations of a simplified superconductor quench model. Results show that decreasing the specific heat exponent can prevent a quench from occurring and improve quench resilience, though in our simple model the effects are small. Further work will be necessary to establish the practical feasibility of this approach.

Section: Modelmentioning

confidence: 99%

Can Topological Transitions be Exploited to Engineer Intrinsically Quench-Resistant Wires?

Whittlesea

Quintanilla

Annett

et al. 2018

“…Voltage taps were installed across each DP of the coil at the joint locations for quench detection and joint resistance measurement. Modular signal conditioning electronics with very high accuracy and stability, and with isolation had been developed in-house for measurements of these sensors and quench detection [9], [10].…”

Section: Experimental Test Design and Descriptionmentioning

confidence: 99%

Cryogenic Acceptance Tests of SST-1 Superconducting Coils

Sharma

Prasad

Doshi

et al. 2015

Toroidal field (TF) and poloidal field (PF) coils of steady-state superconducting tokamak (SST-1) have been fully refurbished to ensure cryostable and low-dc-resistance interpancake and intercoil joints, helium leak tightness of the winding pack, and > 10 MΩ winding pack to ground insulation resistance under cold conditions. As per SST-1 mission mandate, all TF coils and PF3 Top had been cold tested at full operational parameters. A dedicated large coil test facility was integrated for these tests. Specially adapted solutions such as magnet preparation cum transport stand, demountable busbar supports, demountable sensor mountings, reusable joints for busbar connections inside cryostat, etc., were developed. These measures led to timely and successful completion of cold tests and integration of the magnet system on to the SST-1 machine shell. The functionality of various diagnostics of the magnet system was also established during these tests. Details of coil refurbishment, test facility, test campaigns, and some important test results are reported in this paper. in solid-nitrogen-cooled MgB 2 -based persistent magnet development. Since 2006, he has been working with the SST-1 Magnet Group, Institute for Plasma Research, Gandhinagar, India. His current research interests include development of superconducting joint for MgB 2 conductors; design, analysis, development, and validation of superconducting magnets. A. Panchal received the B.E. degree in mechanical engineering. He is currently working with the SST-1 Magnet Group. His research interests include tool development and fabrication of superconducting magnets.S. J. Jadeja is currently a Welder with the SST-1

“…With the constant nominal flow of 1.25 g/s through the double pancake hydraulic paths, these end pancakes and bus-bars and their joints typically took six hours additional cooling before the magnets were declared ready for the current charging. The quench detection circuit employed in these campaigns has built-in redundancy [7]. The quenches are enabled with an uncompensated normal zone voltage of 150 mV lasting in excess of 100 ms [8].…”

Section: Toroidal Field Coil Testmentioning

confidence: 99%

SST-1 Toroidal Field Magnet Tests: Some Results and Lessons Learnt

Pradhan

2012

Self Cite

Testing each of the SST-1 Toroidal Field (TF) Magnets under representative conditions in cold with nominal currents was one of the primary and mandatory requisite in the refurbishment of the Steady-State Superconducting Tokamak (SST-1). Under this mandate prior to the SST-1 machine shell re-assembly, each of the 16 SST-1 TF magnets have been tested fully and successfully in a dedicated test stand. The campaign began on June 10, 2010 and was concluded on Jan 24, 2011 spanning over seven and half months without any interruption in-between. These campaigns ensured that all the sixteen TF magnets could be charged to their nominal currents of 10000 A in either two-phase or supercritical cooling conditions with leak-tight inter-double pancake resistances being in the range of 150 pico-ohms to 1200 pico-ohms. Sensors and diagnostics signal conditioning and data acquisitions, magnet quench detection and magnet protection aspects in these campaigns have been precise, extensive and redundant wherever feasible. Test team had many failures as well as several learning in the course of these challenging tasks. Magnet preparations for the tests, the test designs and their executions, some exciting and confidence building experimental results as well as some failure experiences have been presented in this paper.