20-OH, NBI.pdf

Introduction to Nuclear Fusion. Prof. Dr. Yong-Su Na. How to heat up a plasma?. 2. Plasma Heating. http://iter.rma.ac.be/en/img/Heating.jpg. 3. Ohmic heating. 4. Ohmic Heating Electric blanket. Auction (Korea). • Intrinsic primary heating in tokamaks due to Joulian dissipation generated by currents through resistive plasma: thermalisation of kinetic energies of energetic electrons (accelerated by applied E) via Coulomb collision with plasma ions • Primary heating due to lower cost than other auxiliary heatings. 5. Ohmic Heating Φ. ICS. Ip Vp. ICS. Lp. dI p dt. Ip. + I p Rp = Vp = −. dφ dt. http://en.wikibooks.org/w/index.php?title=File:Transformer.svg&filetimestamp=20070330220406. 6. Ohmic Heating PΩ = η j. 2.  Bφ  Z eff   1   = 1.0 × 10  3 / 2     T   qo (qa − qo / 2)  R 5.   . 2. - Zeff limited by radiation losses - High T required for enough fusion reactions q0, qa limited by instabilities Magnetic field limited by engineering → compact high-field tokamak. 7. Ohmic Heating. τE =. Z eff    Bφ 1 2 5 PΩ = η j = 1.0 × 10  3 / 2     T   qo (qa − qo / 2)  R = PL = 3nT / τ E  Z eff τ E T = 2.7 ×10   nqa q0 8. Z eff = 1.5.   . 2 5.  Bφ   R.   .   . 2. W W 3 / 2(niTi + neTe ) ≈ = ∂W Pin Pin Pin − ∂t. 4 5. qa qo = 1.5. τ E = (n / 10 20 )a 2 / 2 Alcator scaling 4 5. T = 0.87 Bφ. Average temperatures above ~ 7 keV are necessary before alpha heating is large enough to achieve a significant fusion rate. Weston M. Stacey, “Fusion Plasma Physics” WILEY-VCH (2005). 8. Ohmic Heating. τE =. Z eff    Bφ 1 2 5 PΩ = η j = 1.0 × 10  3 / 2     T   qo (qa − qo / 2)  R = PL = 3nT / τ E  Z eff τ E T = 2.7 ×10   nqa q0 8. Z eff = 1.5.   . 2 5.  Bφ   R.   .   . 2. W W 3 / 2(niTi + neTe ) ≈ = ∂W Pin Pin Pin − ∂t. 4 5. qa qo = 1.5. τ E = (n / 10 20 )a 2 / 2 Alcator scaling 4 5. T = 0.87 Bφ. It seems unlikely that tokamaks that would lead to practical reactors can be heated to thermonuclear temperatures by Ohmic heating! Weston M. Stacey, “Fusion Plasma Physics” WILEY-VCH (2005). 9. Neutral Beam Injection (NBI). 10. Neutral Beam Injection 259-Car Autobahn pile-up near Braunschweig, largest in German history: (20 July 2009). - More than 300 ambulances, fire engines and police cars rushed to the scene to tend to the 66 people injured in the crash. - The crash was blamed on cars aquaplaning on puddles and a low sun hindering drivers. 11. Neutral Beam Injection 259-Car Autobahn pile-up near Braunschweig, largest in German history: (20 July 2009). - More than 300 ambulances, fire engines and police cars rushed to the scene to tend to the 66 people injured in the crash. - The crash was blamed on cars aquaplaning on puddles and a low sun hindering drivers. 12. Neutral Beam Injection. 13. Neutral Beam Injection NBI. Plasma. Neutral beam Andy Warhol. • Supplemental heating by energy transfer of neutral beam to the plasma through collisions • Requirements - Enough energy for deep penetration - Enough power for desired heating - Enough repetition rate and pulse length > τE http://www.nasa.gov/mission_pages/galex/20070815/f.html. 14. Neutral Beam Injection Injection of a beam of neutral fuel atoms (H, D, T) at high energies* ⇓ Ionisation in the plasma. B H,D,T. ⇓ Beam particles confined ⇓ Collisional slowing down * Eb = 120 keV and 1 MeV for KSTAR and ITER, respectively. 15. Dirk Hartmann, “Plasma Heating”, IPP Summer School, IPP Garching, September 20, 2001. Neutral Beam Injection • Neutraliser. - Charge exchange:. + + + → + D D D D  2  2 fast fast gas. - Re-ionisation:. slow. + − + → + + D D D e D  2  2 fast fast gas. gas. - Efficiency: (outgoing NB power)/(entering ion beam power). 16. Neutral Beam Injection. • Energy Deposition in a Plasma Ion collision:. D fast + D + → D +fast + D D fast + D + → D +fast + D + + e. Electron collision:. D fast + e → D +fast + e + e. Charge exchange:. Attenuation of a beam of neutral particles in a plasma NBI. n: density σ: cross section. beam energy. Andy Warhol http://www.nasa.gov/mission_pages/galex/20070815/f.html. http://www.doopediat.com/_upload/image1/50000/53000/400/53018.jpg. 17. Neutral Beam Injection. • Energy Deposition in a Plasma Ion collision:. D fast + D + → D +fast + D D fast + D + → D +fast + D + + e. Electron collision:. D fast + e → D +fast + e + e. Charge exchange:. Attenuation of a beam of neutral particles in a plasma. dN b ( x ) = − N b ( x )nσ tot N b ( x ) = N b (0) exp(− nσ tot x ) dx Ex. beam intensity: I ( x ) = N ( x )v = I ⋅ exp(− x / λ ) b b 0. λ=. 1 nσ tot. ≈ 0.4m. Penetration (attenuation) length. n = 5 ⋅10 20 m −3 Eb 0 = 70keV. σ tot = 5 ⋅10 −20 m 2. In large reactor plasmas, beam cannot reach core!. 18. Dirk Hartmann, “Plasma Heating”, IPP Summer School, IPP Garching, September 20, 2001. Neutral Beam Injection. • Energy Deposition in a Plasma Ion collision:. D fast + D + → D +fast + D D fast + D + → D +fast + D + + e. Electron collision:. D fast + e → D +fast + e + e. Charge exchange:. Attenuation of a beam of neutral particles in a plasma General criterion for adequate penetration. λ≡. 1 γ nσ tot Z eff. 5.5 ×1017 Eb (keV ) = ≥ a/4 −3 γ A(amu )n(m ) Z eff. γ Eb ≥ 4.5 ×10 −19 AnaZ eff. 19. Dirk Hartmann, “Plasma Heating”, IPP Summer School, IPP Garching, September 20, 2001. Neutral Beam Injection. • Energy Deposition in a Plasma Ion collision:. D fast + D + → D +fast + D D fast + D + → D +fast + D + + e. Electron collision:. D fast + e → D +fast + e + e. Charge exchange:. Attenuation of a beam of neutral particles in a plasma. 20. Dirk Hartmann, “Plasma Heating”, IPP Summer School, IPP Garching, September 20, 2001. Neutral Beam Injection. • Energy Deposition in a Plasma Ion collision:. D fast + D + → D +fast + D D fast + D + → D +fast + D + + e. Electron collision:. D fast + e → D +fast + e + e. Charge exchange:. Attenuation of a beam of neutral particles in a plasma. 21. Dirk Hartmann, “Plasma Heating”, IPP Summer School, IPP Garching, September 20, 2001. Neutral Beam Injection • Generation of a Neutral Fuel Beam Extraction acceleration grids. Ion source. D+. .. D+ D2+. D+, e-. 100 kV. Deflection magnet. D2. Low temperature D plasma, 5 eV. -3 kV. 0 kV. Vacuum valve. Neutraliser. .. B. D+. .. Beam duct. D. D. Beam dump. Ex) W7-AS: V = 50 kV, I = 25 A, power deposited in plasma: 0.4 MW. 22. Dirk Hartmann, “Plasma Heating”, IPP Summer School, IPP Garching, September 20, 2001. Neutral Beam Injection • Ion Source. 23. Neutral Beam Injection • Ion Acceleration. 24. Neutral Beam Injection • Ion Neutralisation. 25. Neutral Beam Injection • Ion Deflection. 26. Neutral Beam Injection •Neutral Injection. 27. Neutral Beam Injection • JET NBI System. 28. Neutral Beam Injection • JET NBI System. 29. Neutral Beam Injection • JET NBI System. JET with machine and Octant 4 Neutral Injector Box. 30. https://www.euro-fusion.org/eurofusion/europe-participates/czech-republic/. Neutral Beam Injection • JET NBI System. Octant 4 Neutal Injector Box. 31. https://www.euro-fusion.org/eurofusion/europe-participates/czech-republic/. Neutral Beam Injection • Injection Angle. B. Radial (perpendicular, normal) injection Tangential injection. Radial injection:. B. • standard ports • particle loss • shine-through. 1 B × ∇B v D ,∇B = ± v⊥ rL 2 B2. .. ∇B 32. Dirk Hartmann, “Plasma Heating”, IPP Summer School, IPP Garching, September 20, 2001. Neutral Beam Injection • Injection Angle. Radial (perpendicular, normal) injection. B. Tangential injection. KSTAR NB shine-through armor 33. Dirk Hartmann, “Plasma Heating”, IPP Summer School, IPP Garching, September 20, 2001. Neutral Beam Injection ASDEX Upgrade. JET. 34.