1 / 24

Electrodes and PROTO-PINCH Presented by A. Mancuso

Associazione Euratom -ENEA sulla Fusione. Electrodes and PROTO-PINCH Presented by A. Mancuso. PROTO-SPHERA Workshop - Frascati, 18-19/03/2002. Associazione Euratom-ENEA sulla Fusione. Outline. PROTO-SPHERA Requirements PROTO-PINCH Experiment Cathode, Anode & Diagnostics

marah-madden
Download Presentation

Electrodes and PROTO-PINCH Presented by A. Mancuso

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Associazione Euratom-ENEA sulla Fusione Electrodes and PROTO-PINCHPresented by A. Mancuso PROTO-SPHERA Workshop - Frascati, 18-19/03/2002

  2. Associazione Euratom-ENEA sulla Fusione Outline • PROTO-SPHERA Requirements • PROTO-PINCH Experiment • Cathode, Anode & Diagnostics • Extrapolation to PROTO-SPHERA PROTO-SPHERA Workshop - Frascati, 18-19/03/2002

  3. Associazione Euratom-ENEA sulla Fusione PROTO-SPHERARequirements • Arc Current, up to 60 kA • Electron Emissivity ( 1 MA/m2) • Arc Power, up to 6.0-10 MW • Power Density Handling Capability (20-30 MW/m2) PROTO-SPHERA Workshop - Frascati, 18-19/03/2002

  4. Associazione Euratom-ENEA sulla Fusione PROTO-PINCH Testbench • Test of 1/100 of the PROTO-SPHERA Cathode& Anode • Arcbreakdown in configurationsimilar to ProtoSphera. • Effects of the arc current Ie≤1 kA, with qPinch≥ 2. PROTO-SPHERA Workshop - Frascati, 18-19/03/2002

  5. Associazione Euratom-ENEA sulla Fusione PROTO-PINCH Discharges Image of PROTO-PINCH Hydrogen plasma with Ie=600 A, B=1 kG. PROTO-PINCH has produced Hydrogen and Helium arcs in the form of screw pinch discharges. Pinch Length : 75 cm Stabilizing Field : 1.5 kGSafety Factor qPinch≥2Ie = 670 AEmax = 6.7 A/cm2Vpinch = 80 –120 VVcathode = 14.5 V PROTO-SPHERA Workshop - Frascati, 18-19/03/2002

  6. Associazione Euratom-ENEA sulla Fusione Cathode Layout Material Plates: MolybdenumColumns:TantalumInsulator : AluminaCoils : Pure W Module Power = 8.4 KWModule Current = 670 AModule Voltage = 14.5 VWire Number = 4Wire Length = 40.0 cmWire Surface = 4X25 cm2Wire Temp =2600 °CWire Em =6.7 Amp/cm2Wire Weight = 4X22 Gr. PROTO-SPHERA Workshop - Frascati, 18-19/03/2002

  7. Associazione Euratom-ENEA sulla Fusione Cathode Treatments & Results Filling Pressure 1 · 10-3 – 1 · 10-2 mbar • AC current for heating the cathode, to spread the ion plasma current over the filaments. • Time required for heating the cathode circa 15 s. •   Icath=550-590 A (rms.) at Vcath=14.5 V (rms.) allows for Ie=600-670 A of plasma current Ie/Icath≈1. •  Pcathode≈ 8.5 kW allows for Pe≈50-70 kW into the Pinch. • No damagesafter »400 shots at Ie=600 A, Dt = 2-5 sec PROTO-SPHERA Workshop - Frascati, 18-19/03/2002

  8. Associazione Euratom-ENEA sulla Fusione HeliConical Coil HeliConical Coil Conical Wire&TerminalClamp Molybdenum Plates • Null Field • Optimize Temperature Distribution • Optimize Weight Distibution • Ie =167 A(each coil) • DPFS= Ie/PFS~ 1 MA/m2 Wires 1 out 4T = 2600 °C Ground AC Power 14.5 V Ic=150A Tantalum Column Double HelicalZeroField Plasma Face SurfacePFS=1.5 10-4m2 d=2mm AluminaInsulator D= 14 mm PROTO-SPHERA Workshop - Frascati, 18-19/03/2002

  9. Associazione Euratom-ENEA sulla Fusione HeliConical Coil Test Test Results : • Very Small Displacement after 2700 Sec at 2700 °C PROTO-SPHERA Workshop - Frascati, 18-19/03/2002

  10. Associazione Euratom-ENEA sulla Fusione Structural Analysis Max Stress 0.16 Kg/mm2 • Max VonMisessStress= 0.16 Kg/mm2 • s2700°C =0.85 Kg/mm2 • Safety Factor = s2700°C / Stress ~ 5 PROTO-SPHERA Workshop - Frascati, 18-19/03/2002

  11. Associazione Euratom-ENEA sulla Fusione Anode a b ·PWAnode= 2/3 (670 120) KW » 56 KW ( module)·Asurface ~1 • 10-3 m2·Dpw= PW/ Asurface ~ 50 MW/m2·anode arcanchoringwithCathodeDC heated (a)·No Anode anchoring with ACcathode heating(b) • NoDamages after 1000 discharge • Material W 95% Cu5%. • Scheme : Puffed Hollow Anode PROTO-SPHERA Workshop - Frascati, 18-19/03/2002

  12. Associazione Euratom-ENEA sulla Fusione Anode Extrapolation to PROTO-SPHERA Gas Puff Ie OFHC CU W Cu5% TotSurf = 0.2 m2 Anode Power Handling Capability:PROTO-PINCH=670A •120V ~80 KW (2-5sec)(ProtoSphera/ ProtoPinch)AnodeSurface~100ProtoSpheraTestedup to 100 * 80 KW = 8 MWProtoSpheraMax ~6.0 – 10 MW ( < 1 sec) Gas Puff PROTO-SPHERA Workshop - Frascati, 18-19/03/2002

  13. Associazione Euratom-ENEA sulla Fusione Cathode - Extrapolation to ProtoSphera Molybdenum • Cathode Emissivity • Coil Material :Pure W • Wire Diameter = 2 mm • Total Coils Number = 378 • Single Coil emission = 167 A • Tot126 module 3 X 167.5 A »63 KA • Current Density »1 MA/m2 Conical Wire Terminal & Clamp PROTO-SPHERA Workshop - Frascati, 18-19/03/2002

  14. Associazione Euratom-ENEA sulla Fusione H2 H2 Zoom He zoom He Å Å Å Å Å VisibleSpectroscopy Spectral lines of filling gas (H2/He) and impurities Enlarged Å Å 1 eV <Te 3.0 eV - No HeII (4686 Å) He Very few impuritiesOII& CIIIat a count level» 10-2of the largest Helium line counts Å PROTO-SPHERA Workshop - Frascati, 18-19/03/2002

  15. Associazione Euratom-ENEA sulla Fusione Density Measurements • 2mm microwave interferometer with 140 GHz oscillator : • B = 1.25 kG :ne =4•1018m-3per fringeÞne ~1.6·1019m-3 • Density measurable • In Helium discharge up to Ie = 200 A • Line-averaged electron density increase linearly with current Ie • Helium ionization degree is about 16% at filling pressure of 4 10-3 mbar & Ie= 200 A Ie fringes PROTO-SPHERA Workshop - Frascati, 18-19/03/2002

  16. Associazione Euratom-ENEA sulla Fusione MODELING of PROTO-PINCH PLASMA • Ohmic input = electron flow convected fluxÞTePinch~ 2 eV • Good agreement withSpectroscopy Þ1<TePinch<3 eV • Interferometry suggests Þplasma 50% ionized at Ie=600 AÞpH2=8•10-3 mbar gives: nePinch~ 2•1020 m-3 • Estimated Ohmic inputPW ~4kW-Ptotpinch ~50kW • electrode plasma sheaths Pelectrodes =Ptotpinch - PW~46 kW • solvingpower injected near the electrodes equation and electron flow near the sheets equation : • Teelectrodes~0.4 eV - neelectrodes~5•1020 m-3 PROTO-SPHERA Workshop - Frascati, 18-19/03/2002

  17. Associazione Euratom-ENEA sulla Fusione EXTRAPOLATION to Screw Pinch ofPROTO-SPHERA • Assuming same plasma near the electrodes at Ie=60 kA • Teelectrodes~0.4 eV, neelectrodes~5•1020 m-3 • Power into electrode sheaths Pelectrodes=100•46 kW = 4.6 MW •  In the main body of the discharge (far from electrode sheaths) Ohmic input = electron flow convected flux: TePinch =36 eV;Constant electron pressure: nePinch =1.5•1019 m-3 • Ohmic inputPW = 5.4 MW • OHMIC PW 5.4 MW + • SHEATHS Pelectrodes 4.6 MW + • Helicity Injection PHI 0.6 MW = • TOTAL POWER PPinch 10.6 MW PROTO-SPHERA Workshop - Frascati, 18-19/03/2002

  18. Associazione Euratom-ENEA sulla Fusione Conclusions • Arcbreakdown in configurationsimilar to ProtoSphera :OK • Stable arc Ie≤1 kA, with qPinch≥ 2 : OKCapability to fulfill ProtoSphera requirements : • Arc Current, up to 60 kA : OK • Electron Emissivity ( 1 MA/m2) : OK • Arc Power handling capability : OK • Test of : 1/100 of the ProtoSphera Cathode & Anode : OK PROTO-SPHERA Workshop - Frascati, 18-19/03/2002

  19. Associazione Euratom-ENEA sulla Fusione Answers to Panel Questions • Are the PROTO-PINCH electrode experiments a sufficient technical basis for a reliable electrode operation in PROTO-SPHERA ? : YES • How likely in the proposed experiment to advance the present state of science and tecnology ...? : Anode & Cathode load, both in energy and power are relevant for, ITER and fusion reactor,divertor and plasma facing components. PROTO-SPHERA Workshop - Frascati, 18-19/03/2002

  20. Associazione Euratom-ENEA sulla Fusione W Impurities (Spectroscopy ) FHa= 2.5 10-4 Fnoise = 5 • 10-3 FW= FHaFnoise=125 nH2= 2 • 1020 1/m3 SHa=1.010-16m3/sec; SHa/XBHa=20 -> XBHa= 5 • 10-18m3/sec SW=8 10-15m3/sec; SW/XBW = 10 -> XBW = 8 • 10-16m3/sec nWS =( FW/ FHa ) (XBHa/XBW) nH2 ~ 6 • 1015 1/m3 Zeff = ( nH2 (ZH2)2 +nW (ZW)2 )/(nH2 + nW ) ~ 1 PROTO-SPHERA Workshop - Frascati, 18-19/03/2002

  21. Associazione Euratom-ENEA sulla Fusione W Impurities ( Pressure ) nH2=2 • 1020 1/m3 PH2 = 8 • 10-3 mbar Facrcy= 5/100 PW2700°C = 1 10-5 mbar nW = (PW2700°C /PH2) nH2 = 1.25 • 1016 1/m3 nWp/ nWS =6 1015 1/m3/1.25 1/m3= 2 PROTO-SPHERA Workshop - Frascati, 18-19/03/2002

  22. Associazione Euratom-ENEA sulla Fusione • = 8 ; ks = 9.78 •103/A3/2 m/s; Sel=2•10-2 m2Power injected in Plasma sheatsPelPinch = 1.6 10-19 Sel g ks nel Tel3/2 Wattunder condition constant electron pressure (plasma body – electrodes )flow near the sheats -> 2 nel•Tel =ne•Te= 5.31020 eV/m3Tel = 0.49 eV4.6•104=1.610-19 2•10-2g ksnel Tel3/2 nel = 5.4 1020 1/m3 MODELING of PROTO-PINCH PLASMA Ie=600 A ; < rPinch > = 0.1 m, ; B = 1 kG, qPinch~2 ; Lc= 1.33 • LPinch ~1 m LnL=8 ; Zeff=2 ; <Jpinch>= 1.9 • 104 A/m2 ; s = 2 102 lnL Te3/2/ZeffPWPinch=p < rPinch >2 1.33 Lpinch/ sneglecting radiation loss the convected flux : Ppinch= 5/2<JPinch>Tep < rPinch >2equating the terms->Te=2.45 eVin good agreement with spectroscopy1<Te<3assuming plasmais 50% ionized and PH2=8 • 10-3 mbar -> ne~2•10201/m3 PWPinch~4 kW, Ppinch=50 kW -> Power in Plasma Sheats PelPinch ~46 kW PROTO-SPHERA Workshop - Frascati, 18-19/03/2002

  23. Associazione Euratom-ENEA sulla Fusione EXTRAPOLATION to Screw Pinch ofPROTO-SPHERA Sel=2 m2; Lpinch =2m ; Lc= 2 • LPinch ~ 4m; < rPinch > = 0.04 m LnL=10 ; Zeff=2 ; Ie=60 103A;<Jpinch>= 1.2 • 107 A/m2 ; s = 2 102 lnL Te3/2/ZeffAssuming plasma parameters near electrodes the same as PROTO-PINCHTel = 0.49 eV, nel = 5.4 1020 1/m3PWPinch=p < rPinch >2 2 Lpinch/ s = 5.4 MWneglecting radiation loss the convected flux :Ppinch= 5/2<JPinch>Tep < rPinch >2equating the terms ->Te~36 eV2 nel•Tel =ne•Te= 5.3 1020 eV/m3->ne = 1.5 1019 1/m3Therefore thePower injected into the plasma sheets is : PelPinch = 1.6 10-19 Sel g ks nel Tel3/2 Watt= 4.6 MW PROTO-SPHERA Workshop - Frascati, 18-19/03/2002

  24. Associazione Euratom-ENEA sulla Fusione Emissivity vs Temperature (1) PROTO-SPHERA Workshop - Frascati, 18-19/03/2002

More Related