Fabrication of new joints for SST-1 TF coil winding packs

Prasad, Upendra; Sharma, Anjali; Patel, Dipak; Doshi, K.; Khristi, Y.; Varmora, P.; Chauhan, Piyush; Jadeja, S.J.; Gupta, Pratibha; Pradhan, Subrata

doi:10.1016/j.fusengdes.2013.06.005

Cited by 12 publications

(4 citation statements)

References 4 publications

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“…These aspects have raised possibilities of cryo-stable and reliable operation of magnets with two-phase cooling and current leads with cold gas in future machines. SST-1 also has the unique distinction of ∼0.3 n dc joint resistances in superconducting winding packs [29] as compared to the joint resistance of the EAST device (10-30 n ) [30]. SST-1, being a high aspect (R = 1.1 and a = 0.2 m) ratio machine, holds a spectrum of toroidal plasma studies in the high aspect ratio too.…”

Section: Significant Achievements In Engineering and Physics In Sst-1mentioning

confidence: 99%

The first experiments in SST-1

Pradhan¹,

Khan²,

Tanna³

et al. 2015

Nucl. Fusion

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A steady state superconducting tokamak (SST-1) has been commissioned after the successful experimental and engineering validations of its critical sub-systems. During the 'engineering validation phase' of SST-1; the cryostat was demonstrated to be leak-tight in all operational scenarios, 80 K thermal shields were demonstrated to be uniformly cooled without regions of 'thermal runaway and hot spots', the superconducting toroidal field magnets were demonstrated to be cooled to their nominal operational conditions and charged up to 1.5 T of the field at the major radius. The engineering validations further demonstrated the assembled SST-1 machine shell to be a graded, stress-strain optimized and distributed thermo-mechanical device, apart from the integrated vacuum vessel being validated to be UHV compatible etc. Subsequently, 'field error components' in SST-1 were measured to be acceptable towards plasma discharges. A successful breakdown in SST-1 was obtained in SST-1 in June 2013 assisted with electron cyclotron pre-ionization in the second harmonic mode, thus marking the 'first plasma' in SST-1 and the arrival of SST-1 into the league of contemporary steady state devices.Subsequent to the first plasma, successful repeatable plasma start-ups with E ∼ 0.4 V m −1 , and plasma current in excess of 70 kA for 400 ms assisted with electron cyclotron heating pre-ionization at a field of 1.5 T have so far been achieved in SST-1. Lengthening the plasma pulse duration with lower hybrid current drive, confinement and transport in SST-1 plasmas and magnetohydrodynamic activities typical to large aspect ratio SST-1 discharges are presently being investigated in SST-1. In parallel, SST-1 has uniquely demonstrated reliable cryo-stable high field operation of superconducting TF magnets in the two-phase cooling mode, operation of vapour-cooled current leads with cold gas instead of liquid helium and an order less dc joint resistance in superconducting magnet winding packs with high transport currents. In parallel, SST-1 is also continually getting up-graded with first wall integration, superconducting central solenoid installation and over-loaded MgB 2 -brass based current leads etc. Phase-1 of SST-1 up-gradation is scheduled by the first half of 2015, after which long pulse plasma experiments in both circular and elongated configurations have been planned in SST-1.

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Section: Significant Achievements In Engineering and Physics In Sst-1mentioning

confidence: 99%

The first experiments in SST-1

Pradhan¹,

Khan²,

Tanna³

et al. 2015

Nucl. Fusion

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“…The TF coil casing was suitably machined to accommodate these joints with a bigger size than the earlier joints. More details of this joint are available in [5], [6].…”

Section: A Fabrication Of New Joints and Manifoldsmentioning

confidence: 99%

“…Demountable and adjustable supports designed with a combination of SS frames and glassfiber sheets allowed fast removal and reinstallations of CICC busbar supports and to take care of minor variations in busbar locations due to variation in locations of coil terminals as a part of coil fabrication tolerance. The busbar joint box concept was slightly modified from inter-DP joint design [5]. The joint box was made from a single pipe and end caps for fast removal and reinstallation of busbar joints.…”

Section: Major Challengesmentioning

confidence: 99%

“…This drastically reduced the failures or nonperformance of the coil or of its components during the cold test. For example, during the entire joint fabrication process, the solder filling quality of each coil termination was checked by an ultrasonic test before making a lap joint [5], [14]. After manufacturing the lap joint, its resistance was measured in RT to ensure its quality.…”

Section: Major Challengesmentioning

confidence: 99%

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Cryogenic Acceptance Tests of SST-1 Superconducting Coils

Sharma

Prasad

Doshi

et al. 2015

IEEE Trans. Appl. Supercond.

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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

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