Design of the HTS Fusion Conductors for TF and CS Coils

Bykovsky, Nikolay; Uglietti, D.; Wesche, R.; Bruzzone, Pierluigi

doi:10.1109/tasc.2015.2509178

Cited by 5 publications

(6 citation statements)

References 6 publications

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“…The Nb47%wt.Ti alloy used in ITER was developed for the MRI market to maximise J c between 4-6 T; the Nb 3 Sn strands were developed for particle accelerator magnets to maximise J c between 8-10 T; and the aim of the REBCO industry has focussed on developing higher J c tapes (at reduced cost) for power applications and ultra high field magnets. REBCO cables for tokamaks are currently being optimised for immediate use -CORC [174], slotted core cables [36,175], twisted-stack cables [176,177]) -but commercial fusion will drive the development of new REBCO conductors. As we have seen in section 6, the huge fusion magnets in our optimised REBCO design include magnet support structures that are stress limited.…”

Section: Fusion-specific Superconducting Materialsmentioning

confidence: 99%

Training and Upgrading Tokamak Power Plants with Remountable Superconducting Magnets

L.¹,

Surrey²,

Naish³

et al. 2022

Preprint

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All high field superconductors producing magnetic fields above 12 T are brittle. Nevertheless, they will probably be the materials of choice in commercial tokamaks because the fusion power density in a tokamak scales as the fourth power of magnetic field. Here we propose using robust, ductile superconductors during the reactor commissioning phase in order to avoid brittle magnet failure while operational safety margins are being established. Here we use the PROCESS systems code to inform development strategy and to provide detailed capital-cost-minimised tokamak power plant designs. We propose building a 'demonstrator' tokamak with an electric power output of 100 MW e , a plasma fusion gain Q plasma = 17, a net gain Q net = 1.3, a cost of electricity (COE) of $ 1148 (2021 US) per MW h (at 75 % availability) and high temperature superconducting operational TF magnets producing 5.4 T on-axis and 12.5 T peak-field. It uses Nb-Ti training magnets and will cost about $ 9.75 Bn (2021 US). An equivalent 500 MW e plant has a COE of $ 608 per MW suggesting that large tokamaks may eventually dominate the commercial market. We consider a range of designs optimised for capital cost (as the reactors considered are pilot plants) consisting of both 100 MW e and 500 MW e plants with each of two approaches for the magnets: training and upgrading. With training magnets, the plant is cost-optimised for REBCO TF magnets. For a 100 MW e plant, the Nb-Ti training magnets typically produce 70 % peak field on the toroidal field coils compared to REBCO magnets, 65 % peak field on the central solenoid and cost ≈ 10 % of the total machine cost. Training magnets could in principle be reused for each of say 10 subsequent (commercial) machines and hence at 1 % bring only marginal additional cost. With upgrade magnets the plant is more expensive -first it is cost-optimised for Nb-Ti and then upgraded to REBCO coils. The upgrade increases the net electrical output from 100 to 280 MW e with an ≈ 25 % increase in reactor capital cost. We also evaluate likely advances in fusion technology and find that technologies on the horizon will probably not bring further large reductions in capital cost, and that REBCO magnets are generally stress-limited rather than current density limited. We conclude that: the fusion community should develop high B c2 alloys specifically for fusion applications; superconductors should be tested under operational-like radiation at cryogenic temperatures; and that we should proceed now with detailed design and construction of a prototype fusion power plant that integrates and de-risks all the key technologies including high temperature superconducting cables and joints using remountable training magnets, and hence is the last tokamak before commercialisation of fusion energy.

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Section: Fusion-specific Superconducting Materialsmentioning

confidence: 99%

Training and Upgrading Tokamak Power Plants with Remountable Superconducting Magnets

L.¹,

Surrey²,

Naish³

et al. 2022

Preprint

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“…Using the numerical model described in the previous section, parametric studies for n and τ have been performed for the strand and cable cases. For a given set of the geometrical parameters ('configuration'), n and τ were extracted from the Q(ν) curve as the fitting parameters for equation (2). Based on a large set of calculated configurations (in total, 341 configurations for the strand and 350 for the cable), analytical dependencies have been built for n and τ , which are discussed below.…”

Section: Scaling Laws For Energy Lossmentioning

confidence: 99%

“…There are four geometrical parameters of the strand, which were used in the parametric study of n and τ : diameter of the strand D, width of the slot w, height of the slot t and twist-pitch h (see [2]). The cross-section is simply taken as S = πD 2 /4.…”

Section: A Intra-strand Energy Lossmentioning

confidence: 99%

“…The sample was tested at T = 5 K in the collinear DC field B = 1 T and AC sinusoidal field B a = 0.4 T. The results of the measurements are presented in the left plot of figure 4. For the given strand parameters the shape factor and the time constant are computed from equation ( 3) as n = 0.232 and τ = 0.292 s, which allows us to calculate the intra-strand loss Q intra from equation (2). The hysteresis loss Q hyst was obtained as in [1].…”

Section: A Intra-strand Energy Lossmentioning

confidence: 99%

“…Unfortunately, the studied geometry of the cable is not the one for which n and τ are deduced. Therefore, it will be attempted to express them using the parameters of the strand and cable design (see definitions in [2]) by help of the electrical network model, similar to those extensively developed for the Rutherford cables [3]- [6]. Comparing with other models, it will also be considered the finite thickness of the cable core, g = 0.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

AC Loss in HTS Fusion Cables: Measurements, Modeling, and Scaling Laws

Bykovsky

Uglietti

Wesche

et al. 2018

IEEE Trans. Appl. Supercond.

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Currently, the use of HTS cables in the high field sections of central solenoid (CS) of DEMO is one of the most appealing applications of the HTS cables in fusion magnets. Due to the pulsed operation of such coils minimization of the AC loss is necessary for the CS conductors. For the stacked-tape HTS cable layout proposed at the Swiss Plasma Center (SPC), the main contributions in the total AC loss -hysteresis loss in stacks, intra-and inter-strand coupling losses -have been studied. The electrical network model is used for the coupling losses, based on which the scaling laws for the AC energy loss are proposed. On a basis of the developed numerical tools the assessment of the AC loss for the next HTS cable prototypes at SPC is also reported. More than 50 % reduction of the total AC loss is expected compared with the first TF cable prototypes tested in EDIPO.

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