scholarly journals Can the development of fusion energy be accelerated? An introduction to the proceedings

2019 ◽  
Vol 377 (2141) ◽  
pp. 20170446 ◽  
Author(s):  
Colin Windsor
Keyword(s):  
High Temperature ◽  
Power Plants ◽  
High Temperature Superconductors ◽  
Fusion Energy ◽  
High Plasma ◽  
Plasma Pressure ◽  
Fukushima Accident ◽  
Fusion Power ◽  
Current Densities ◽  
Faster Development

This introduction reviews the unique opportunity of fusion power to deliver safe, carbon-free, abundant, base-load power. The differences from fission power are considered: especially why a Chernobyl, Three Mile Island or Fukushima accident could not happen with a fusion reactor. The Lawson triple product is introduced, along with tokamaks, or magnetic bottles, whose ability to approach close to the fusion burn conditions has so far put them above their competitors. Our last fusion power Discussion Meeting was organized by Derek Robinson FRS in 1998, and the progress since then is reviewed. Tokamaks are introduced, and the advantages of spherical tokamaks are listed along with the special engineering challenges that they introduce. Their key advantage is high plasma pressure, and the important β parameter indicating the efficiency of the magnetic field use is introduced. High-temperature superconductors are described along with the opportunities they allow for higher magnetic fields at higher current densities and more modest cryogenic temperatures. The question posed is whether the two developments of spherical tokamaks and high-temperature superconductors could lead to more economical fusion power plants and faster development than the current route through ITER and DEMO. This article is part of a discussion meeting issue ‘Fusion energy using tokamaks: can development be accelerated?’.

scholarly journals Smaller and quicker with spherical tokamaks and high-temperature superconductors

2019 ◽  
Vol 377 (2141) ◽  
pp. 20170438 ◽  
Author(s):  
Melanie Windridge
Keyword(s):  
High Temperature ◽  
Plasma Physics ◽  
Power Plants ◽  
High Temperature Superconductors ◽  
Fusion Energy ◽  
Subsequent Paper ◽  
Research Areas ◽  
Theoretical Advantage ◽  
Game Changer ◽  
Compact Shape

Research in the 1970s and 1980s by Sykes, Peng, Jassby and others showed the theoretical advantage of the spherical tokamak (ST) shape. Experiments on START and MAST at Culham throughout the 1990s and 2000s, alongside other international STs like NSTX at the Princeton Plasma Physics Laboratory, confirmed their increased efficiency (namely operation at higher beta) and tested the plasma physics in new regimes. However, while interesting devices for study, the perceived technological difficulties due to the compact shape initially prevented STs being seriously considered as viable power plants. Then, in the 2010s, high-temperature superconductor (HTS) materials became available as a reliable engineering material, fabricated into long tapes suitable for winding into magnets. Realizing the advantages of this material and its possibilities for fusion, Tokamak Energy proposed a new ST path to fusion power and began working on demonstrating the viability of HTS for fusion magnets. The company is now operating a compact tokamak with copper magnets, R 0  ∼ 0.4 m, R / a  ∼ 1.8, and target I p  = 2MA, B t0  = 3 T, while in parallel developing a 5 T HTS demonstrator tokamak magnet. Here we discuss why HTS can be a game-changer for tokamak fusion. We outline Tokamak Energy's solution for a faster way to fusion and discuss plans and progress, including benefits of smaller devices on the development path and advantages of modularity in power plants. We will indicate some of the key research areas in compact tokamaks and introduce the physics considerations behind the ST approach, to be further developed in the subsequent paper by Alan Costley. This article is part of a discussion meeting issue ‘Fusion energy using tokamaks: can development be accelerated?’.

scholarly journals Overview of the SPARC tokamak

2020 ◽  
Vol 86 (5) ◽  
Author(s):  
A. J. Creely ◽  
M. J. Greenwald ◽  
S. B. Ballinger ◽  
D. Brunner ◽  
J. Canik ◽  
...  
Keyword(s):  
High Temperature ◽  
High Field ◽  
High Performance ◽  
Power Plants ◽  
High Temperature Superconductors ◽  
Fusion Energy ◽  
Current Status ◽  
Fusion Plasma ◽  
Design Work ◽  
Barium Copper

The SPARC tokamak is a critical next step towards commercial fusion energy. SPARC is designed as a high-field ( $B_0 = 12.2$ T), compact ( $R_0 = 1.85$ m, $a = 0.57$ m), superconducting, D-T tokamak with the goal of producing fusion gain $Q>2$ from a magnetically confined fusion plasma for the first time. Currently under design, SPARC will continue the high-field path of the Alcator series of tokamaks, utilizing new magnets based on rare earth barium copper oxide high-temperature superconductors to achieve high performance in a compact device. The goal of $Q>2$ is achievable with conservative physics assumptions ( $H_{98,y2} = 0.7$ ) and, with the nominal assumption of $H_{98,y2} = 1$ , SPARC is projected to attain $Q \approx 11$ and $P_{\textrm {fusion}} \approx 140$ MW. SPARC will therefore constitute a unique platform for burning plasma physics research with high density ( $\langle n_{e} \rangle \approx 3 \times 10^{20}\ \textrm {m}^{-3}$ ), high temperature ( $\langle T_e \rangle \approx 7$ keV) and high power density ( $P_{\textrm {fusion}}/V_{\textrm {plasma}} \approx 7\ \textrm {MW}\,\textrm {m}^{-3}$ ) relevant to fusion power plants. SPARC's place in the path to commercial fusion energy, its parameters and the current status of SPARC design work are presented. This work also describes the basis for global performance projections and summarizes some of the physics analysis that is presented in greater detail in the companion articles of this collection.

Small, modular and economically attractive fusion enabled by high temperature superconductors

2019 ◽  
Vol 377 (2141) ◽  
pp. 20180354 ◽  
Author(s):  
Dennis Whyte
Keyword(s):  
Magnetic Field ◽  
High Temperature ◽  
Magnetic Fields ◽  
Current Density ◽  
High Temperature Superconductors ◽  
Fusion Energy ◽  
High Magnetic Fields ◽  
Operating Temperatures ◽  
The Magnetic Field ◽  
Game Changer

The advantages of high magnetic fields in tokamaks are reviewed, and why they are important in leading to more compact tokamaks. A brief explanation is given of what limits the magnetic field in a tokamak, and why high temperature superconductors (HTSs) are a game changer, not just because of their higher magnetic fields but also for reasons of higher current density and higher operating temperatures. An accelerated pathway to fusion energy is described, defined by the SPARC and ARC tokamak designs. This article is part of a discussion meeting issue ‘Fusion energy using tokamaks: can development be accelerated?’.

scholarly journals On the size of tokamak fusion power plants

2019 ◽  
Vol 377 (2141) ◽  
pp. 20170437 ◽  
Author(s):  
Hartmut Zohm
Keyword(s):  
Power Plants ◽  
New Technology ◽  
Fusion Energy ◽  
Plasma Parameters ◽  
Fusion Power ◽  
Figures Of Merit ◽  
Superconducting Coils ◽  
Critical Technology ◽  
Alternative Approach ◽  
Major Radius

Figures of merit for future tokamak fusion power plants (FPPs) are presented. It is argued that extrapolation from present-day experiments to proposed FPPs must follow a consistent development path, demonstrating the largest required leaps in intermediate devices to allow safe extrapolation to an FPP. This concerns both plasma physics and technology. At constant plasma parameters, the figures of merit depend on both major radius R and magnetic field B . We propose to use the term ‘size’ for a combination of R and B to avoid ambiguities in scaling arguments. Two routes to FPPs are discussed: the more conventional one increasing R , based on the assumption that B is limited by present technology; and an alternative approach assuming the availability of new technology for superconducting coils, allowing higher B . It is shown that the latter will lead to more compact devices, and, assuming a criterion based on divertor impurity concentration, is in addition more favourable concerning the exhaust problem. However, in order to obtain attractive steady-state tokamak FPPs, the required plasma parameters still require considerable progress with respect to present experiments. A credible strategy to arrive at these must hence be shown for both paths. In addition, the high-field path needs a demonstration of the critical technology items early on. This article is part of a discussion meeting issue ‘Fusion energy using tokamaks: can development be accelerated?’.

Important Considerations for Processing Bi-Based High-Temperature Superconducting Tapes and Films for Bulk Applications

MRS Bulletin ◽  
1992 ◽  
Vol 17 (8) ◽  
pp. 45-51 ◽  
Author(s):  
Eric E. Hellstrom
Keyword(s):  
High Temperature ◽  
Magnetic Fields ◽  
Materials Science ◽  
Weak Link ◽  
High Temperature Superconductors ◽  
Electromagnetic Properties ◽  
High Magnetic Fields ◽  
Large Current ◽  
Current Densities ◽  
Made In

High-temperature superconductors are brittle oxide ceramics, yet they have been made into wire that has been wrapped into solenoids and used in demonstration magnets and motors. Fabricating wires from these ceramics is an extremely challenging materials science process that requires a precisely engineered microstructure with the correct chemical, mechanical, and electromagnetic properties if these wires are to transport large current densities (Jc) in high magnetic fields. Heine et al. first demonstrated that wires of these materials could carry high Jc in very high magnetic fields. At 4.2 K, the oxide superconducting wires can carry higher Jc at higher magnetic fields than conventional Nb-Ti or Nb3Sn wires (Figure 1), and as shown in the companion article in this issue by Kato et al. they can also have high Jc at 77 K.Of the three major families of high-temperature superconductors, YBa2Cu3O7-x, Bi-Sr-Ca-Cu-O (BSCCO), and Tl-Ba-Ca-Cu-O, the best wires to date have been made in the BSCCO system. At present, all YBa2Cu3O7-x wires are weak linked and have only small Jc in magnetic fields. In the Tl-based system, the superconducting properties are potentially very interesting, but the toxicity of Tl and the system's complex processing have limited conductor development. For the Bi-based system, the basic processing steps are becoming known, the grains are well connected, and the weak link problem can be controlled. This permits applications in the temperature range 4–77 K, depending on the field and current density requirements of the particular use.

Improvement of critical current densities by fission tracks in U-doped high temperature superconductors

1998 ◽  
Vol 11 (10) ◽  
pp. 1001-1005 ◽  
Author(s):  
M Eisterer ◽  
S Tönies ◽  
W Novak ◽  
H W Weber ◽  
R Weinstein ◽  
...  
Keyword(s):  
High Temperature ◽  
Critical Current ◽  
High Temperature Superconductors ◽  
Fission Tracks ◽  
Current Densities

Irradiation Response of Next Generation High Temperature Superconductors for Fusion Energy Applications

2014 ◽  
Vol 66 (1) ◽  
pp. 57-62 ◽  
Author(s):  
Keith J. Leonard ◽  
Tolga Aytug ◽  
Albert A. Gapud ◽  
Fredrick A. List III ◽  
Nathan T. Greenwood ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperature Superconductors ◽  
Fusion Energy ◽  
Next Generation ◽  
Energy Applications
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