electrodes and proto-pinch presented by a. mancuso
DESCRIPTION
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 - PowerPoint PPT PresentationTRANSCRIPT
Electrodes and PROTO-PINCH
Presented by A. Mancuso
PROTO-SPHERA Workshop - Frascati, 18-19/03/2002
Associazione Euratom-ENEA sulla Fusione
Outline
1)PROTO-SPHERA Requirements2)PROTO-PINCH Experiment3)Cathode, Anode & Diagnostics4)Extrapolation to PROTO-SPHERA
PROTO-SPHERA Workshop - Frascati, 18-19/03/2002
Associazione Euratom-ENEA sulla Fusione
PROTO-SPHERA Requirements
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
Associazione Euratom-ENEA sulla Fusione
PROTO-PINCH Testbench
Test of 1/100 of the PROTO-SPHERA
Cathode& Anode
Arc breakdown in configuration similar to ProtoSphera.
Effects of the arc current Ie≤1 kA, with qPinch≥ 2.PROTO-SPHERA Workshop - Frascati, 18-19/03/2002
Associazione Euratom-ENEA sulla Fusione
PROTO-PINCH has produced Hydrogen and Helium arcs in the form of screw pinch discharges.
Image of PROTO-PINCH Hydrogen plasma with Ie=600 A, B=1 kG.
Pinch Length : 75 cm Stabilizing Field : 1.5 kGSafety Factor qPinch≥2
Ie = 670 AEmax = 6.7 A/cm2
Vpinch = 80 –120 VVcathode = 14.5 V
PROTO-PINCH Discharges
PROTO-SPHERA Workshop - Frascati, 18-19/03/2002
Associazione Euratom-ENEA sulla Fusione
Cathode Layout
Material Plates: MolybdenumColumns:TantalumInsulator : AluminaCoils : Pure WModule Power = 8.4 KWModule Current = 670 AModule Voltage = 14.5 VWire Number = 4Wire Length = 40.0 cmWire Surface = 4X25 cm2
Wire Temp = 2600 CWire Em = 6.7 Amp/cm2
Wire Weight = 4X22 Gr.
PROTO-SPHERA Workshop - Frascati, 18-19/03/2002
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 damages after 400 shots at Ie= 600 A, t = 2-5 sec
PROTO-SPHERA Workshop - Frascati, 18-19/03/2002
Associazione Euratom-ENEA sulla Fusione
HeliConical Coil
HeliConical Coil
Wires 1 out 4T = 2600 C
Ground
Conical Wire&Terminal
Clamp
Tantalum Column
AC Power14.5 V
D= 14 mm
d=2mm AluminaInsulator
Double HelicalZeroField
Molybdenum Plates
Ic=150A
Null FieldOptimize Temperature DistributionOptimize Weight Distibution Ie =167 A (each coil)DPFS= Ie/PFS
m2
Associazione Euratom-ENEA sulla Fusione
PROTO-SPHERA Workshop - Frascati, 18-19/03/2002
Plasma Face SurfacePFS=1.5 10-4m2
HeliConical Coil Test Test Results :
Very Small Displacement after 2700 Sec at 2700 C
PROTO-SPHERA Workshop - Frascati, 18-19/03/2002
Associazione Euratom-ENEA sulla Fusione
Structural Analysis
Max VonMisess Stress = 0.16 Kg/mm2
C = 0.85 Kg/mm2
Safety Factor = C Stress PROTO-SPHERA Workshop - Frascati, 18-19/03/2002
Associazione Euratom-ENEA sulla Fusione
W - Bending Proof Strength vs Temperature
0.40
0.50
0.60
0.70
0.80
0.90
1.00
1.10
1.20
1.30
1.40
1.50
2300 2400 2500 2600 2700 2800 2900 3000 3100 3200
Temperature (° C)
(K
g/m
m2)
A
Max Stress 0.16 Kg/mm2
Anode
NoDamages after 1000 discharge
Material W 95% Cu5%.
Scheme : Puffed Hollow Anode
PWAnode = 2/3 (670 120) KW W ( module) Asurface 1 • 10-3 m2
Dpw = PW/ Asurface MW/m2
anode arc anchoringwithCathode DC heated (a) No Anode anchoring with AC cathode heating (b)
a b
PROTO-SPHERA Workshop - Frascati, 18-19/03/2002
Associazione Euratom-ENEA sulla Fusione
Anode Extrapolation to PROTO-SPHERA
W Cu5%
Gas Puff Ie
TotSurf = 0.2 m2
Anode Power Handling Capability:PROTO-PINCH=670A • 120V 80 KW (2-5sec)
(ProtoSphera/ ProtoPinch)AnodeSurface 100
ProtoSpheraTested up to 100 * 80 KW = 8 MWProtoSpheraMax 6.0 – 10 MW ( < 1 sec)
OFHC CU
Gas Puff
PROTO-SPHERA Workshop - Frascati, 18-19/03/2002
Associazione Euratom-ENEA sulla Fusione
Cathode - Extrapolation to ProtoSphera
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
Molybdenum
Conical Wire Terminal & Clamp
PROTO-SPHERA Workshop - Frascati, 18-19/03/2002
Associazione Euratom-ENEA sulla Fusione
VisibleSpectroscopy
Spectral lines of filling gas (H2/He ) and impurities
1 eV < Te 3.0 eV - No HeII (4686 Å)
EnlargedÅ
Å
Å
He
Very few impurities
OII & CIII at a count level
of the largest Helium line counts
H2 ZoomH2
ÅÅ ÅÅÅ
He zoomHe
PROTO-SPHERA Workshop - Frascati, 18-19/03/2002
Associazione Euratom-ENEA sulla Fusione
Density Measurements
2mm microwave interferometer with 140 GHz oscillator :
B = 1.25 kG : ne = 4•1018m-3 per fringe ne 61019 m-3
Density measurableIn Helium discharge up to Ie = 200 ALine-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
fringes
Ie
PROTO-SPHERA Workshop - Frascati, 18-19/03/2002
Associazione Euratom-ENEA sulla Fusione
MODELING of PROTO-PINCH PLASMA
Ohmic input = electron flow convected flux TePinch 2 eV
Good agreement with Spectroscopy 1<TePinch<3 eV
Interferometry suggests plasma 50% ionized at Ie=600 A pH2=8•10-3 mbar gives: ne
Pinch 2•1020 m-3
Estimated Ohmic input P 4kW - Ptotpinch 50kW
electrode plasma sheaths Pelectrodes Ptotpinch - P 46 kW
solvingpower injected near the electrodes equation and electron flow near the sheets equation :Te
electrodes 0.4 eV - neelectrodes 5•1020 m-3
PROTO-SPHERA Workshop - Frascati, 18-19/03/2002
Associazione Euratom-ENEA sulla Fusione
EXTRAPOLATION to Screw Pinch of PROTO-SPHERA Assuming same plasma near the electrodes at Ie=60 kATe
electrodes 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 input P = 5.4 MW
OHMIC P 5.4 MW +
SHEATHS Pelectrodes 4.6 MW +
Helicity Injection PHI 0.6 MW =
TOTAL POWER PPinch 10.6 MWPROTO-SPHERA Workshop - Frascati, 18-19/03/2002
Associazione Euratom-ENEA sulla Fusione
ConclusionsAssociazione Euratom-ENEA sulla Fusione
PROTO-SPHERA Workshop - Frascati, 18-19/03/2002
Arc breakdown in configuration similar to ProtoSphera : OK
Stable arc Ie≤1 kA, with qPinch≥ 2 : OK
Capability 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
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.
Associazione Euratom-ENEA sulla Fusione
PROTO-SPHERA Workshop - Frascati, 18-19/03/2002
W Impurities (Spectroscopy )
H
noise = 5 • 10-3
W = Hnoise = 125nH2 = 2 • 1020 1/m3
SHm3/sec; SHXBHXBH•m3/secSWm3/sec; SWXBW XBW
•m3/secnWS =( W/ HXBH/XBW) nH2 •1/m3
Zeff = ( nH2 (ZH2)2 + nW (ZW)2 )/(nH2 + nW )
Associazione Euratom-ENEA sulla Fusione
PROTO-SPHERA Workshop - Frascati, 18-19/03/2002
W Impurities ( Pressure )
nH2 = 2 • 1020 1/m3
PH2 = 8 • 10-3 mbar
Facrcy= 5/100PW2700C = 1 10-5 mbarnW = (PW2700C /PH2) nH2 •1/m3
nWp/ nWS = 1/m31/m3
Associazione Euratom-ENEA sulla Fusione
PROTO-SPHERA Workshop - Frascati, 18-19/03/2002
MODELING of PROTO-PINCH PLASMA
Associazione Euratom-ENEA sulla Fusione
PROTO-SPHERA Workshop - Frascati, 18-19/03/2002
Ie=600 A ; < Pinch > = 0.1 m, ; B = 1 kG, qPinch2 ; Lc= 1.33 • LPinch m LnZeff=2 ; <Jpinch>= 1.9 • 104 A/m2 ; 2 102 lnTe
3/2/Zeff
PPinch=< Pinch >2 1.33 Lpinch/ neglecting radiation loss the convected flux :
Ppinch= 5/2<JPinch>Te< Pinch >2 equating the terms ->Te=2.45 eV in good agreement with spectroscopy 1<Te<3assuming plasma is 50% ionized and PH2=8 • 10-3 mbar -> ne2•10201/m3
PPinchkW , Ppinch= 50 kW -> Power in Plasma Sheats Pel
Pinch kWks• m/s; Sel=2•10-2 m2
Power injected in Plasma sheats
PelPinch = 1.6 10-19 Sel ks nel Tel
3/2 Watt
under condition constant electron pressure (plasma body – electrodes )
flow near the sheats -> 2 nel•Tel =ne•Te= 5.31020 eV/m3 Tel = 0.49 eV
4.6•104=1.610-19 2•10-2 ks nel Tel3/2 nel = 5.4 1020 1/m3
EXTRAPOLATION to Screw Pinch of PROTO-SPHERA
Associazione Euratom-ENEA sulla Fusione
PROTO-SPHERA Workshop - Frascati, 18-19/03/2002
Sel=2 m2; Lpinch = 2m ; Lc= 2 • LPinch m; < Pinch > = 0.04 m LnZeff=2 ; Ie=60 103A; <Jpinch>= 1.2 • 107 A/m2 ; 2 102 lnTe
3/2/Zeff
Assuming plasma parameters near electrodes the same as PROTO-PINCHTel = 0.49 eV, nel = 5.4 1020 1/m3
PPinch=< Pinch >2 2 Lpinch/ 5.4 MW
neglecting radiation loss the convected flux :
Ppinch= 5/2<JPinch>Te< Pinch >2 equating the terms -> Te36 eV2 nel•Tel =ne•Te= 5.3 1020 eV/m3 -> ne = 1.5 1019 1/m3
Therefore the Power injected into the plasma sheets is : Pel
Pinch = 1.6 10-19 Sel ks nel Tel3/2 Watt = 4.6 MW
Emissivity vs Temperature (1)Associazione Euratom-ENEA sulla Fusione
PROTO-SPHERA Workshop - Frascati, 18-19/03/2002