Challenge toward Lower Aspect Ratio Challenge toward Lower Aspect - PowerPoint PPT Presentation

1. Cover Page Challenge toward Lower Aspect Ratio Challenge toward Lower Aspect Ratio JAERI Tokamak Tokamak Power Reactor ower Reactor JAERI 10th International Spherical Torus Workshop & US-Japan Exchange Meeting on the Spherical Torus Sept. 29 – Oct. 1, 2004 at Kyoto Univ, JAPAN S.NISHIO and Reactor Design Team JAERI ; Naka Fusion Research Establishment Naka-machi, Naka-gun Ibaraki-ken 311-0193, JAPAN Nishio@ naka.jaeri.go.jp Contents (1)ST Plasma, Its Higher Performance (2)Possible Reactor Concepts with ST Plasma (3)Super-conducting Ｔｏｒｏｉｄａｌ Ｆｉｅｌｄ Coil (4)Normal-conducting Ｔｏｒｏｉｄａｌ Ｆｉｅｌｄ Coil

2. Why Compact ？ A Craving for Compact & Lightweight JAERI JAERI Sensitive Parameters ？ Neutron Wall Load ＆ Power Core Components Plasma Beta ＆ Toroidal Coil

3. CS-less Discard of Center Solenoid Coil Discard of Center Solenoid Coil JAERI JAERI CS Coil Support Wheel In due time, they fall into disuse !!

4. To VECTOR To VECTOR To VECTOR JAERI JAERI COIL Maximum Field, B MAX (T) 25 100 Density, i AVE (A/mm 2 ) Average Current 20 80 ( A~4 ) ( A~4 ) 60 15 40 10 5 20 0 0 0 0.5 1 1.5 2 2.5 Center Post Radius, R CP (m) CS-less R.L. Miller et al., Normalized Beta ， β N Phys. Plasma 4 (4), April 1997 10 8 PLASMA ( A~ 2 ) ( A~ 2 ) 6 Weight Power Density 4 2 ST Region 0 1 A Conventional 1.5 ， ， 2 2 o Region Ellipticity, κ 3 i 3 t a 4 4 R 5 t 5 c VECTOR e p s A

5. This is VECTOR This is the VECTOR. This is the VECTOR. JAERI JAERI 18.2 m Replacement Unit Simple Simple Vacuum Maintenance Boundary Scheme Plasma Major Radius : R P = 3.2 m Fusion Power : P F = 2.5 GW Plasma Minor Radius : a P = 1.4 m Neutron Wall Load : P n = 5 MW/m 2 Plasma Ellipticity : κ = 2.35 Field on axis : B 0 = 5 T Plasma Current : I P = 14 MA Reactor Weight : W = 8800 Ton Normalized Beta : β N = 5.7 Weight Power Dens. : p = 280 kW/ton

6. Where is VECTOR Where is VECTOR ? Where is VECTOR ? JAERI JAERI ARIES-ST 26m 30 m 18.2m ARIES-RS 20 m VECTOR ITER

7. Light TFC Why CS-less TFC is so lightweight ? Why CS-less TFC is so lightweight ? JAERI JAERI TFC weight is in proportion to the stored energy !

8. Tough Structure CS-less TFC Concept, Its characteristics. CS-less TFC Concept, Its characteristics. JAERI JAERI Solid Post Structure Barrel Structure ( Apple Shape ) ( conventional ) Same Area : 2 π R B t= π R P2 Same Load : W = 2 π R B p B = 2 π R P p P p B p P 2R P 2R B Wedge Support t Isotropic Support σ r ~0 σ r = σ θ = -p P σ θ = -(R B /t)p B The “ Solid ” is stronger than the “ Barrel ” by 5 times.

9. TFC Design Flow Design Flow of SC-ST TF Coil Design Flow of SC-ST TF Coil JAERI JAERI Optimization of TFC Material Compositon CP Area Design Current Density of Filament Superconducting Filament Area TFC Ampere-turns Center Post TFC Shape Stored Energy Conductor Current Electromagnetic Terminal Voltage Force of TFC System Allowable Current Structural Decay Rate Material Structural One Sector Joule Heating Material Area Conductor Stabilizer Area Cooling Channel Area Insulator Area Cooling Channel Bi2212 Strands Plasma Design Pb Neutronics Design Insulator Area

10. Plasma Design Flow Plasma Design Flow Plasma Design Flow JAERI JAERI Radius of Normalized Beta ， β N Center Post 10 Current Density 8 Max. Field, B Max 6 Shield Thickness, ∆ 4 Plasma Major Radius, R 2 P ST Region Field on Axis, B 0 0 1 Conventional 1.5 Minor Radius, a 2 2 P Aspect Ratio ， A Region Ellipticity, κ Ellipticity, κ 3 3 4 4 Plasma Temp. 5 5 MHD Safety Factor, q Ψ Plasma Current, I P Plasma Dens. Plasma Power Balance Confinement, NO HH y2 =1.8 Plasma Dens., n/n GW =1.0 YES Where is optimum point?

11. Summary Summary Summary JAERI JAERI (i) Heavy tokamak is caused by heavy TFC. (ii) CS-less leads to lightweight tokamak. (iii) ST power reactor with NC TFC is skeptical. Urgent Issue ● High δ plasma equilibrium ● Break-down & Current ramp-up

Parameter Space JAERI JAERI