This paper reports a study of HTS pancake coils without turn-to-turn insulation. Three no-insulation (NI) were wound: each single and double coil Bi2223 conductor one ReBCO conductor. An equivalent electrical circuit for modeling NI was verified by two sets test: 1) charge-discharge; 2) sudden discharge. Also, an overcurrent test in which current exceeding coil's critical 2.3 times performed, analysed, to demonstrate that terms stability outperform their counterparts. The new winding offers...

This paper presents experimental and analytical studies on the characteristic resistance of NI (no-insulation) ReBCO pancake coils, which are used in an equivalent circuit model to characterize 'radial as well spiral' current paths within coils. We identified turn-to-turn contact a major source coil. In order verify this, three single HTS coils—60, 40, 20 turns—were fabricated with their winding tension carefully maintained constant. A sudden discharge test was performed each coil obtain its...

A 26 T 35 mm winding diameter all-GdBa2Cu3O (GdBCO) magnet was designed by the MIT Francis Bitter Magnet Laboratory, and constructed tested SuNAM Co., Ltd. With multi-width (MW) no-insulation (NI) high temperature superconductor (HTS) technique incorporated, is highly compact; its overall height are 172 327 mm, respectively. It consists of a stack NI double pancake coils wound with MW GdBCO tapes in five different widths ranged 4.1–8.1 mm. In bath liquid nitrogen at 77 K, had charging time...

Stability margin of a high-temperature superconducting (HTS) coil is two or three orders magnitude greater than that low-temperature coil. In recent years, many papers have reported test results turn-to-turn no-insulation (NI) HTS coils having extremely enhanced thermal stability, such burnout never occurs in an NI coil, even at operating current exceeding 2.5 times the critical current. Thus, The main goal this paper to clarify transient electromagnetic and behaviors mechanism high...

A high-resolution 1.3-GHz/54-mm low-temperature superconducting/high-temperature superconducting (HTS) nuclear magnetic resonance magnet (1.3 G) is currently in the final stage at Massachusetts Institute of Technology Francis Bitter Magnet Laboratory. Its key component a three-coil (Coils 1-3) 800-MHz HTS insert comprising 96 no-insulation (NI) double-pancake coils, each wound with 6-mm-wide GdBCO tape. In this paper, after describing overall 1.3-G system, we present innovative design...

This paper reports a study on BSCCO and ReBCO HTS (high temperature superconducting) test coils, layer-wound double-pancake, with without turn-to-turn insulation. Over current tests were performed in bath of liquid nitrogen to compare stabilities the coils at 77 K. Saturation magnetic fields from NI (no insulation) both ReBCO, was observed owing bypassing through contacts local quenches operating currents higher than their critical currents. In global occurred coil quench recoveries during...

This paper reports a study of two HTS racetrack coils wound with GdBCO coated conductors, one without turn-to-turn insulation and the other Nomex insulation. The were characterized by charge-discharge, over-current, sudden discharge tests. Thermal electrical characteristics coil outperformed insulated one. test results confirmed that although has slow charging/discharging time constant, no-insulation winding technique may enable compact protection-free racetrack-typed enhanced mechanical...

A no-insulation (NI) technique has been applied to wind and test a NI HTS (YBCO) double-pancake coil at 4.2 K. Having little detrimental effect on field-current relationship, the absence of turn-to-turn insulation enabled survive quench current density 1.58 kA/mm2. The is compact self-protecting, two features suitable for large high-field magnets. To investigate beneficial impacts >1 GHz LTS/HTS NMR magnets, we have designed six new inserts our ongoing 1.3 magnet, which require less costly...

This paper presents the over-current quench test and post-quench operation results of a 7 T 78 mm winding diameter multi-width (MW), no-insulation (NI) magnet in bath liquid helium at 4.2 K. The MW-NI consists 13 double-pancake (DP) coils wound with GdBCO tapes having five different widths ranging from 4.1–8.1 mm. After reached 7.3 253 A, current was further increased purposely until quenched 312 corresponding to density 895 A mm−2 for central DP narrowest 4.1 tape. NI showed fast...

We present a No-Insulation (NI) Multi-Width (MW) winding technique for an HTS (high temperature superconductor) magnet consisting of double-pancake (DP) coils. The NI enables self-protecting and the MW minimizes detrimental anisotropy in current-carrying capacity tape by assigning tapes multiple widths to DP coils within stack, widest top bottom sections narrowest midplane section. This paper presents fabrication test results NI-MW demonstrates unique features technique: enhanced field...

No-insulation (NI) REBCO magnets have many advantages. They are self-protecting, therefore do not need quench detection and protection which can be very challenging in a high Tc superconducting magnet. Moreover, by removing insulation allowing thinner copper stabilizer, NI significantly higher engineering current density mechanical strength. On the other hand, drawbacks of long magnet charging time field-ramp-loss. In principle, these mitigated managing turn-to-turn contact resistivity (Rc)....

REBCO coated conductors are now being used for building very high-field magnets with large electromagnetic stresses, both expected ones due to transport current × stresses and additional resulting from the screening currents inherent in wide tapes. Post mortem analyses of several recent test coils operated above 40 T show that significant conductor plastic deformation occurs, even JBR well below ∼1 GPa yield Hastelloy substrate conductor. To investigate these mechanisms, were unwound after...

The partial insulation winding was examined to ameliorate the slow charge–discharge shown by coils wound without insulation. Single pancake of GdBCO coated conductor were insulation, with kapton tape every five turns, and full use tape. They characterized charge–discharge, sudden discharge, over-current testing. improved charging discharging high thermal electrical stabilities partially insulated coil demonstrate its potential for in HTS power applications.

This paper presents experimental and analytical studies on the time-varying behavior of an NI (no-insulation) high-temperature superconductor pancake coil, alone or magnetically coupled to external coil. An coil another insulated (as external), both identical winding i.d. number turns, were fabricated. Another used in this study was a 300-mm/5-T low-temperature magnet. equivalent circuit model is proposed simulate under conditions. Good agreement between experiment simulation shows that...

We present assembly and test results of a 3-nested-coil 800-MHz (18.8 T) REBCO insert (H800) for the MIT 1.3 GHz LTS/HTS NMR magnet currently under completion. Each three H800 coils is stack no-insulation (NI) double-pancake (DPs). The innermost 8.7-T Coil 1 (26 DPs) was completed by mid-2016; middle 5.6-T 2 (32 complet-ed in mid-2017; while outermost 4.5-T 3 (38 early 2018. Coils 1, & were assembled together 2018 as 3-nested-coil, H800, tested, first liquid nitrogen to power supply current...

A no-insulation (NI) pancake coil was wound with a 23 m long REBCO tape containing multiple 'defects', at which local critical currents are substantially lower (<80%) than the tape's lengthwise average. During charging test up to 60 in bath of liquid nitrogen 77 K, showed 'defect-irrelevant' behaviors, i.e. terminal voltages and center fields steady-state operations were barely discernible from those an ideal 'defect-free' coil. Also, current (Ic) measured be 68 A, close 72 estimated Ic...

A critical component of the 1.3-GHz nuclear magnetic resonance magnet (1.3 G) program, currently ongoing at Francis Bitter Magnet Laboratory, Plasma Science and Fusion Center, Massachusetts Institute Technology, now approaching its final stage, is all high-temperature superconductor 800-MHz insert (H800). The consists three nested double-pancake (DP) coils fabricated with 6-mm-wide REBCO conductor. Coil 1, innermost coil H800, has already been tested 77 4.2 K. In addition, one third DPs for...

Present research on no-insulation (NI) rare earth barium copper oxide (REBCO) magnets have demonstrated their ability to produce high fields due compact nature. NI often been be self-protecting. However, evidence of mechanical damage in recent field magnets, suggests that there are some issues about quench must resolved for this otherwise promising technology. This article attempts explain multi-physics phenomena occurring during the an magnet can used elucidate behavior through experiments...

This paper describes two general methods: field map processing and NMR lineshape analysis, that we are currently using for the on-going research of improvement techniques specifically applied to our 700 MHz LTS/HTS magnet. The validity methods is verified with comparison between calculations experiments. Also, a simple but effective analysis has been used identify principal source remanent magnetic measured in bore magnet: screening current induced (SCF) from 100-MHz HTS insert, comprised 48...

A high temperature superconducting (HTS) coil without turn-to-turn insulation is proposed for the field of a wind turbine. In case coil, epoxy impregnation generally necessary to protect from mechanical disturbances by time-varying magnetic fields and rotational vibrations provide integrity. This study examined thermal electrical stabilities non-insulated GdBCO racetrack pancake coils impregnated with CTD-521, Stycast 2850 FT, paraffin through cool down, over-current, repetitive cooling...

This paper deals with the latest design of an all High Temperature Superconductor (HTS) insert for our 1.3 GHz NMR program. Due to a loss original 600 MHz HTS insert, entire program was revised, and upon further examination options available which included not only conductor material properties, but also new winding technologies recently developed here at FBML, it has finally been decided build 800 (H800) purely based in SuperPower YBCO conductor. The H800 will still be comprised nested...

The thermal and electrical characteristics of two GdBCO-coated conductor racetrack coils, one insulated with Kapton insulation the other without turn-to-turn insulation, were investigated by typical voltage–current measurement, charge–discharge, sudden discharge, over-current tests respect to external pressures applied straight sections coils. test results show that stabilities coil enhanced considerably increasing pressure up 0.5 MPa, whereas those not affected pressure. non-insulated HTS...

This paper presents a study on the effects of winding tension characteristic resistance no-insulation (NI) coil. Two ReBCO NI test pancake coils, having same i.d. (60 mm), o.d. (67.6 and number turns (60), were sequentially prepared in way that first coil was wound with 12-N, tested, then rewound new 20-N for tests. In each test, energized at target current, power supply "suddenly" disconnected, temporal decay center field measured, from which time constant consequent obtained. To check...

This paper presents our latest experimental results on high-temperature superconducting (HTS) splice joints for HTS insert coils made of YBCO and Bi2223, that comprise a 1.3 GHz low-temperature superconducting/HTS nuclear magnetic resonance magnet currently under development at Francis Bitter Magnet Laboratory. joint resistivity 77 K in these must be reproducible < 100 nΩ cm2. Several tape to (YBCO-YBCO) splice·joint samples were fabricated, their Ic measured K. First, we describe the...