Presentation on theme: "Review of (UPFLF) Plasma Focus Numerical Experiments"— Presentation transcript:
1 Review of (UPFLF) Plasma Focus Numerical Experiments S Lee1,2,3 & H Saw1,21INTI International University, Nilai, Malaysia2Institute for Plasma Focus Studies, Melbourne, Australia3University of Malaya, Kuala Lumpur, MalaysiaInternational Workshop on Plasma Science and Applications, 4 & 5 October 2012, Bangkok, Thailand
2 Plasma Focus Numerical Experiments- Outline of Lecture Development, usage and resultsBasis and philosophyReference for DiagnosticsInsights and frontiersContinuing development- Ion beam modelling
3 UNU ICTP PFF- 3 kJ Plasma Focus Designed for UNU ICTP PFF- 3 kJ Plasma Focus Designed for International Collaboration within AAAPT Background
4 Design of the UNU/ICTP PFF- 3kJ Plasma Focus System Background
5 UNU/ICTP PFF- placed at ICTP, 1988 Background Network: Malaysia, Singapore, Thailand, Pakistan, India, Egypt,Similar machines with designs based on or upgraded:Zimbabwe, Syria, USA, Bulgaria, Iran
6 The Code Intro codeFrom beginning of that program it was realized that the laboratory work should be complemented by computer simulation.A 2-phase model was developed in 1983We are continually developing the model to its present formIt now includes thermodynamics data so the code can be operated in H2, D2, D-T, N2, O2, He, Ne, Ar, Kr, Xe.We have used it to simulate a wide range of plasma focus devices from the sub-kJ PF400 (Chile) , the small 3kJ UNU/ICTP PFF (Network countries), the NX2 3kJ Hi Rep focus (Singapore), medium size tens of kJ DPF78 & Poseidon (Germany) to the MJ PF1000, the largest in the world.An Iranian Group has modified the model, calling it the Lee model, to simulate Filippov type plasma focus .
7 Review of UPFLF Plasma Focus Numerical Experiments Intro code The code10 couples the electrical circuit with PF dynamics, thermodynamics and radiation.Using standard circuit equations and Newtonian equations of motion adapted for the plasma focus:the code is consistent in(a) energy,(b) charge and(c) mass.
8 Development of the code Intro code It was described in and used in the design and interpretation of experiments12-15.An improved 5-phase code incorporating finite small disturbance speed16, radiation and radiation-coupled dynamics was used17-19,It was web-published20 in 2000 andPlasma self- absorption was included20 in 2007
9 Usage Intro codeIt has been used extensively as a complementary facility in several machines, for example: UNU/ICTP PFF12,14,15,17-19, NX219,22, NX119, DENA23, AECSIt has also been used in other machines for design and interpretation including Chile’s sub-kJ PF and other machines24, Mexico’s FNII25 and the Argentinian UBA hard x-ray source26.More recently KSU PF (US), NX3 (Singapore), FoFu I (US) and several Iranian machines APF, Tehran U, AZAD U
10 Information derived Intro code Information computed includesaxial and radial dynamics11,17-23, pinch propertiesSXR emission characteristics and yield17-19, 22, 27-33,design of machines10,12,24,26,optimization of machines10,22, 24,30 and adaptation to Filippov-type DENA23.Speed-enhanced PF17 was facilitated.
11 Information Derived Intro code Scaling Properties;Constancy of energy density (per unit mass) across range of machines14Hence same temperature and density14Constancy of drive current density I/a relating to the speed factor14(I/a)/r0.5Scaling of pinch dimensions & lifetime14 with anode radius ‘a’:pinch radius ratio rp/a =constantpinch length ratio zp/a=constantpinch duration ratio tp/a=constant
12 Recent development and Insights Intro code PF neutron yield calculations34Current & neutron yield limitations35 with reducing L0Wide-ranging neutron scaling lawsWide-ranging soft x-ray scaling laws in various gasesNeutron saturation36,37- cause and Global Scaling LawRadiative collapse 38Current-stepped PF39Extraction of diagnostic data33,40-42Anomalous resistance data43,44 from current signalsBenchmarks for Ion Beams- scaling with E0.
13 Philosophy of our Modelling Philosophy Experimental basedUtility prioritisedTo cover the whole process- from lift-off, to axial, to all the radial sub-phases; and recently to post-focussed phase which is important for advanced materials deposition and damage simulation.
14 Priority of Basis Philosophy Correct choice of Circuit equations coupled to equations of motion ensures:Energy consistent for the total process and each part of the processCharge consistentMass consistentFitting computed current waveform to measured current waveform ensures:Connected to the reality of experiments
15 Priority of Results Philosophy Applicable to all PF machines, existing and hypotheticalCurrent Waveform accuracyDynamics in agreement with experimentsConsistency of Energy distributionRealistic Yields of neutrons, SXR, other radiations; Ions and Plasma Stream (latest-Benchmarks); in conformity with experimentsWidest Scaling of the yieldsInsightful definition of scaling propertiesDesign of new devices; e.g. Hi V & Current-StepDesign new experiments-Radiative cooling & collapse
16 Philosophy, modelling, results & Philosophy, modelling, results & applications of the Lee Model code Philosophy
17 Numerical Experiments Philosophy Range of activities using the code is so wideNot theoreticalNot simulationThe correct description is:Numerical Experiments
18 UPFLF-The Code Control Panel- configured for PF1000 Demo L0 nH C0 mF b cm a cm z0 r0 mW fm fc fmr fcr V0 P0 M.W. A At/Molecular
19 PF1000, ICDMP Poland, the biggest plasma focus in the world PF1000, ICDMP Poland, the biggest plasma focus in the world Firing the PF Demo
20 Fitting: 1. L0 fitted from current rise profile 2 Fitting: 1. L0 fitted from current rise profile 2. Adjust model parameters (mass and current factors fm, fc, fmr, fcr) until computed current waveform matches measured current waveform (sequential processes shown below) Demo
22 PF1000: Yn Focus & Pinch Properties as functions of Pressure Demo
23 Plasma Focus- Numerical Experiments leading Technology Insights Numerical Experiments- For any problem, plan matrix, perform experiments, get results- sometimes surprising, leading to new insightsIn this way, the Numerical Experiments have pointed the way for technology to follow
24 NE showing the way for experiments and technology Insights PF1000 (largest PF in world): 1997 was planning to reduce static inductance so as to increase current and neutron yield Yn. They published their L0 as 20 nHUsing their published current waveform and parameters we showeda. their L0 =33 nHb. their L0 was already at optimumc. that lowering their L0 would be a waste of effort and resources
25 As L0 was reduced from 100 to 35 nH - As expected Results from Numerical Experiments with PF For decreasing L0- from 100 nH to 5 nH Insights 1As L0 was reduced from 100 to 35 nH - As expectedIpeak increased from 1.66 to 3.5 MAIpinch also increased, from 0.96 to 1.05 MAFurther reduction from 35 to 5 nHIpeak continue to increase from 3.5 to 4.4 MAIpinch decreasing slightly to - Unexpected 1.03 MA at 20 nH, 1.0 MA at10 nH, and 0.97 MA at 5 nH.Yn also had a maximum value of 3.2x1011 at 35 nH.
27 Pinch Current Limitation Effect Insights 1 L0 decreases, L-C interaction time of capacitor decreasesL0 decreases, duration of current drop increases due to bigger aCapacitor bank is more and more coupled to the inductive energy transferEffect is more pronounced at lower L0
28 Pinch Current Limitation Effect Insights 1 A combination of two complex effectsInterplay of various inductancesIncreasing coupling of C0 to the inductive energetic processes as L0 is reducedLeads to this Limitation EffectTwo basic circuit rules: lead to such complex interplay of factors which was not foreseen; revealed only by extensive numerical experiments
29 Neutron yield scaling laws and neutron saturation problem Insights 2 One of most exciting properties of plasma focus isEarly experiments show: Yn~E02Prospect was raised in those early research years that, breakeven could be attained at several tens of MJ .However quickly shown that as E0 approaches 1 MJ, a neutron saturation effect was observed; Yn does not increase as much as expected, as E0 was progressively raised towards 1 MJ.Question: Is there a fundamental reason for Yn
30 Global Scaling Law Insights 2 Scaling deterioration observed in numerical experiments (small black crosses) compared to measurements on various machines (larger coloured crosses) Neutron ‘saturation’ is more aptly portrayed as a scaling deterioration-Conclusion of IPFS-INTI UC researchS Lee & S H Saw, J Fusion Energy, (2008)S Lee, Plasma Phys. Control. Fusion, 50 (2008)S H Saw & S Lee.. Nuclear & Renewable Energy Sources Ankara, Turkey, 28 & 29 Sepr 2009.S Lee Appl Phys Lett 95, (2009)Cause: Due to constant dynamic resistance relative to decreasing generator impedance
31 Scaling for large Plasma Focus Scaling 1 Targets:IFMIF (International fusion materials irradiation facility)-level fusion wall materials testing(a major test facility for the international programme to build a fusion reactor)- essentially an ion accelerator
32 IPFS numerical Experiments: Fusion Wall materials testing at the mid-level of IFMIF: 1015 D-T neutrons per shot, 1 Hz, 1 year for dpa- Gribkov Scaling 1IPFS numerical Experiments:
33 Operating Parameters: 35kV, 14 Torr D-T E0=8.2 MJ Possible PF configuration: Fast capacitor bank 10x PF1000-Fully modelled- 1.5x1015 D-T neutrons per shot Scaling 1Operating Parameters: 35kV, 14 Torr D-TBank Parameters: L0=33.5nH, C0=13320uF, r0=0.19mWE0=8.2 MJTube Parameters: b=35.1 cm, a=25.3 cm z0=220cmIpeak=7.3 MA, Ipinch=3.0 MAModel parameters 0.13, 0.65, 0.35, 0.65
35 50 kV modelled- 1.2x1015 D-T neutrons per shot Scaling 1 Operating Parameters: 50kV, 40 Torr D-TBank Parameters: L0=33.5nH, C0=2000uF, r0=0.45mWE0=2.5 MJTube Parameters: b=20.9 cm, a=15 cm z0=70cmIpeak=6.7 MA, Ipinch=2.8 MAModel parameters 0.14, 0.7, 0.35, 0.7Improved performance going from 35 kV to 50 kV
36 IFMIF-scale device Scaling 1 Numerical Experiments suggests the possibility of scaling the PF up to IFMIF mid-scale with a PF1000-like device at 50kV and 2.5 MJ at pinch current of 2.8MASuch a system would cost only a few % of the planned IFMIF
37 Scaling further- possibilities Scaling 2 1. Increase E0, however note: scaling deteriorated already below Yn~E02. Increase voltage, at 50 kV beam energy ~150kV already past fusion x-section peak; further increase in voltage, x-section decreases, so gain is marginalNeed technological advancement to increase current per unit E0 and per unit V0.We next extrapolate from point of view of Ipinch
38 Scaling from Ipinch using present predominantly beam-target : Yn=1 Scaling from Ipinch using present predominantly beam-target : Yn=1.8x1010Ipeak3.8; Yn=3.2x1011Ipinch4.4 (I in MA) Scaling 2
39 SXR Scaling Laws Scaling 3 First systematic studies in the world done in neon as a collaborative effort of IPFS, INTI IU CPR and NIE Plasma Radiation Lab:Ysxr = 8300× Ipinch3.6Ysxr = 600 × Ipeak in J (I in MA).Scaling laws extended to Argon, N and O by M Akel AEC, Syria in collaboration.
40 Special characteristics of SXR-for applications Scaling 3 Not penetrating; for example neon SXR only penetrates microns of most surfacesEnergy carried by the radiation is delivered at surfaceSuitable for lithography and micro-machiningAt low intensity - applications for surface sterilisation or treatment of foodat high levels of energy intensity, Surface hammering effect;, production of ultra-strong shock waves to punch through backing material; or as high intensity compression drivers in fusion scenarios
41 Compression- and Yield- Enhancement methods Scaling 4 Suitable design optimize compressionRole of high voltageRole of special circuits e.g current-stepsRole of radiative cooling and collapse
42 Latest development Latest Modelling: Ion beam fluence Post focus axial shock waves Plasma streams Anode sputtered material
43 Plasma Focus Pinch Latest photo taken by Paul Lee on INTI PF
44 Emissions from the PF Pinch region Latest +Mach500 Plasma stream+Mach20 anode material jet
48 Extracted from V A Gribkov presentation: IAEA Dec 2012
49 Comparing large and small PF’s- Dimensions and lifetimes- putting shadowgraphs side-by-side, same scaleAnode radius 1 cm cmPinch Radius: 1mm mmPinch length: 8mm mmLifetime ~10ns order of ~100 ns
50 Flux out of Plasma Focus Charged particle beamsNeutron emission when operating with DRadiation including Bremsstrahlung, line radiation, SXR and HXRPlasma streamAnode sputtered material
51 Plasma Focus Ion Beam Fluence and Flux –Scaling with Stored Energy E0 Plasma Focus Ion Beam Fluence and Flux –Scaling with Stored Energy E0 LatestMany Measurements on plasma focus ion beams have been publishedInclude various advanced techniques producing a bewildering variety of data using variety of unitsYet to produce benchmark numbers.Our latest work uses the Lee Model code, integrated with experimental measurements to provide the basis for reference numbers and the scaling of deuteron beams versus E0
52 Basic Definition of Ion Beam characteristics Latest Beam number fluence Fib defines (ions m-2)Beam energy fluence defines (J m-2)Flux =fluence x pulse durationBeam number flux Fib/t defines (ions m-2s-1)Beam energy flux defines (W m-2)
53 Modelling the flux Latest Ion beam number fluence is derived from beam-plasma target considerations as:Fibt = Cn Ipinch2zp[ln(b/rp)]/ (prp2 U1/2)ions m-2All SI units:calibration constant Cn =8.5x108; calibrated against experimental point at 0.5MAIpinch=pinch currentzp=pinch lengthb=outer electrode, cathode radiusrp=pinch radiusU=beam energy in eV where in this model U=3x Vmax (max dynamic induced voltage)These values are computed by our code
54 zp=0.188 m, b/rp=16 cm/2.23 cm, ln(b/rp)=1.97, Example: Numerical Experiment for PF1000 based on following fitted parameters: Latest L0=33 nH, C0=1332 uF, r0=6.3 mW b=16 cm, a= 11.6 cm, z0=60 cm fm=0.14, fc=0.7, fmr=0.35, fcr=0.7 V0=27 kV, P0= 3.5 Torr MW=4, A=1, At=2 for deuteriumResults are extracted from dataline after shot:Ipinch=8.63x105 A,zp=0.188 m, b/rp=16 cm/2.23 cm, ln(b/rp)=1.97,U=3Vmax=3x4.21x104 =1.26x105 V
55 From the above; estimate ions/m2 per shot For PF1000 (at 500 kJ) we obtainedJbt =4.3x1020 ions/m2 per shot=4.3x1016 ions/cm2 per shot at 126 keVComputing for various plasma focus we obtain the following table:
56 Table 1: Parameters of a range of Plasma Focus and Table 1: Parameters of a range of Plasma Focus and computed Ion Beam characteristics LatestMachinePF1000DPF78NX3INTIPFNX2PF-5MPF400JE0 (kJ)48631.014.53.42.72.00.4L0 (nH)3355501102040V0 (kV)27601715141628'a' (cm)11.504.002.600.951.901.500.60c=b/a1.41.322.21.7Ipeak (kA)1846961582180382258129Ipinch (kA)86244434812222016584zp (cm)22.214.171.124.82.30.8rp (cm)2.230.620.130.310.220.09t (ns)25541.036.57.630.012.25.1Vmax (kV)4268.335252232.318
57 3.9 3.2 5.7 3.6 3.4 2.4 2.6 Machine IB Ion Fluence (x1020m-2) PF1000 LatestMachineIB Ion Fluence (x1020m-2)PF10003.9DPF783.2NX35.7INTI3.6NX23.4PF5M2.4PF400J2.6IB Ion Flux (x1027m-2s-1)1.57.815.646.711.519.650.4Mean Ion Energy (keV)12620510575669754IB Energy Fluence (x106 J m-2)10.69.64.33.72.2IB Energy Flux (x1013 W m-2)3.125.826.356.412.030.643.2Ion Number (x1014)610039028019110375.9IB Energy (J)12248128447923111585.1(% E0)(2.5)(4.1)(3.3)(0.7)(2.8)(1.3)IB current (kA)380.0152.4124.840.056.749.118.6IB Damage Ftr (x1010 Wm-2s0.5)1.65.25.04.92.1Ion Speed (cm/ms)347443317269250305226Ion Number per kJ (x1014)12.612.719.45.6126.96.36.199Plasma Stream Energy (J)3912039417072493699217(8.1)(12.0)(7.4)(13.7)(4.5)Plasma Stream Speed (cm/ms)188.8.131.52.420.148.635.7
58 Table 2: Summary of Range of Ion beam properties and suggested scaling Ion Beam PropertyUnits (multiplier)RangeSuggested ScalingFluenceIons m-2 ( x1020)2.4 – 7.8independent of E0Average ion energykeVEnergy FluenceJ m-2 (x106)2 - 33Beam exit radiusfraction of radius 'a'scales with 'a'Beam Ion numberIons per kJ ( x1014)*scales with E0Beam energy% of E01.3 – 5.4+Beam chargemC per kJ#Beam durationns per cm of ‘a’8 – 20scales with ‘a’Fluxions m-2 s-1 (x1027)1.5 – 50Energy fluxW m-2 (x1013)3 – 56Beam current% of Ipeak14 – 23scales with IpeakDamage Factor(x1010 Wm-2s0.5)1.6 – 11*= 6 for INTI PF+= 0.7 for INTI PF#= 0.1 for INTI PF
59 (b) Philosophy, modelling, results and (b) Philosophy, modelling, results and applications of the Lee Model code TR Package
60 Plasma Focus Numerical Experiments- Conclusions: We have covered Development, usage and resultsBasis and philosophyReference for DiagnosticsInsights and frontiersContinuing development- Ion beam modelling
61 References10S Lee, Radiative Dense Plasma Focus Computation Package: RADPF. websites)11 S Lee in Radiation in Plasmas Vol II, Ed B McNamara, Procs of Spring College in Plasma Physics (1983) ICTP, Trieste, p , ISBN , Published byWorld Scientific Publishing Co, Singapore (1984)12S Lee, T.Y. Tou, S.P. Moo, M.A. Elissa, A.V. Gholap, K.H. Kwek, S. Mulyodrono, A.J. Smith, Suryadi, W.Usala & M. Zakaullah. Amer J Phys 56, 62 (1988)13T.Y.Tou, S.Lee & K.H.Kwek. IEEE Trans Plasma Sci 17, (1989)14S Lee & A Serban, IEEE Trans Plasma Sci 24, (1996)15 SP Moo, CK Chakrabarty, S Lee - IEEE Trans Plasma Sci 19, (1991)16D E Potter, Phys Fluids 14, 1911 (1971)17A Serban and S Lee, Plasma Sources Sci and Tehnology, 6, 78 (1997)18M H Liu, X P Feng, SV Springham & S Lee, IEEE Trans Plasma Sci. 26, 135 (1998)19S Lee, P.Lee, G.Zhang, X.Feng, V.A.Gribkov, M.Liu, A.Serban & T.Wong. IEEE Trans Plasma Sci, 26, 1119 (1998)20S.Lee in (archival website) (2012)21S. Lee in ICTP Open Access Archive: (2005)22D.Wong, P.Lee, T.Zhang, A.Patran, T.L.Tan, R.S.Rawat & S.Lee. Plasma Sources, Sci & Tech 16, 116 (2007)23V. Siahpoush, M.A.Tafreshi, S. Sobhanian, & S. Khorram. Plasma Phys & Controlled Fusion 47, 1065 (2005)
62 References24L. Soto, P. Silva, J. Moreno, G. Silvester, M. Zambra, C. Pavez, L. Altamirano, H. Bruzzone, M. Barbaglia, Y. Sidelnikov & W. Kies. Brazilian J Phys 34, 1814 (2004)25H.Acuna, F.Castillo, J.Herrera & A.Postal. International conf on Plasma Sci, 3-5 June 1996, conf record Pg12726C.Moreno, V.Raspa, L.Sigaut & R.Vieytes, Applied Phys Letters 89(2006)27S. Lee, R S Rawat, P Lee and S H Saw, J. Appl. Phys. 106, (2009) 28S. H. Saw and S. Lee, Energy and Power Engineering, 2 (1), (2010) 29M. Akel, Sh Al-Hawat, S H Saw and S Lee, J Fusion Energy, 29, 3, (2010) 30S H Saw, P C K Lee, R S Rawat, S Lee, IEEE Trans Plasma Sci, 37, (2009)31Sh. Al-Hawat, M. Akel, S H Saw, S Lee, J Fusion Energy, 31, 13 – 20, (2012) 32Sh Al-Hawat, M. Akel , S. Lee, S. H. Saw, J Fusio Energy 31, (2012) 33S Lee, S H Saw, R S Rawat, P Lee, A.Talebitaher, A E Abdou, P L Chong, F Roy,A Singh, D Wong and K Devi, IEEE Trans Plasma Sci 39, (2011) 34S Lee and S H Saw, J Fusion Energy, 27, (2008) 35S. Lee and S H Saw, Appl. Phys. Lett., 92, (2008) 36S Lee. Plasma Physics Controlled Fusion, (2008)37S Lee. Appl. Phys. Lett (2009)
63 References38S Lee, S. H. Saw and Jalil Ali, J Fusion Energy DOI: /s First Online 26 Feb (2012) 39S Lee and S H Saw, J Fusion Energy DOI: /s First Online 31 January (2012) 40 S Lee, S H Saw, P C K Lee, R S Rawat and H Schmidt, Appl Phys Lett 92, (2008) 41S H Saw, S Lee, F Roy, PL Chong, V Vengadeswaran, ASM Sidik, YW Leong & ASingh, Rev Sci Instruments, 81, (2010) 42 S Lee, S H Saw, R S Rawat, P Lee, R Verma, A.Talebitaher, S M Hassan, A E Abdou,Mohamed Ismail, Amgad Mohamed, H Torreblanca, Sh Al Hawat, M Akel, P L Chong, FRoy, A Singh, D Wong and K Devi, J Fusion Energy 31,198–204 (2012) 43S Lee, S H Saw, A E Abdou and H Torreblanca, J Fusion Energy 30, (2011) 44F M Aghamir and R A Behbahani, J. Plasma Physics: doi: /S in press (2012) 45 S.Lee, S.H.Saw, L..Soto, S V Springham, S P Moo, Plasma Phys and Control. Fusion, (11pp) (2009)46 S.P. Chow, S. Lee and B.C. Tan, J Plasma Phys, (1972).
64 Review of (UPFLF) Plasma Focus Numerical Experiments S Lee1,2,3 & H Saw1,21INTI International University, Nilai, Malaysia2Institute for Plasma Focus Studies, Melbourne, Australia3University of Malaya, Kuala Lumpur, MalaysiaInternational Workshop on Plasma Science and Applications, 4 & 5 October 2012, Bangkok, Thailand
65 a the proven most effective hardware system of the UNU/ICTP PFF with Developing the most powerful training and research system for the dawning of the Fusion Age TR PackageIntegrate:a the proven most effective hardware system of the UNU/ICTP PFF withb the proven most effective numerical experiment system Lee Model codewith emphasis on dynamics, radiation and materials applications.
66 Into the fusion era: Plasma focus for training/Research- A complete package integrating Experiment and Numerical Experiment TR Package(a) Experimental facility: TRPF (repetitive)1 kJ focus: 10 kV 20 uF 80 nHMeasurements:current, voltage sufficient to deduce dynamics and estimate temperaturesFibre-optics, pin diodes; magnetic probes directly measure speeds, ns imagingSXR spectrometry, neutron counters & TOF, ion collectors for radiation & particle measurementsSimple materials processing experiments
67 Into the fusion era: Plasma focus for research training TR Package (b) Numerical Experiments codeTo complement TRPFComputes dynamics and energy distributionsPlasma pinch evolution, size and life timePost focus Ion Beam, plasma stream and anode sputtered materialConnection with reality: through fitting computed current to measured current traceBehaviour of plasma focus and yields as functions of pressure, gases, storage energies, circuit currents and pinch currents.Carry out above experiments with any plasma focus.Optimization of planned plasma focus
68 (a) The proven most effective 3 kJ PF system TR Package The trolley based UNU/ICTP PFF 3 kJ plasma focus trainingand research system will be updated as a 1 kJ system
69 (b) The proven most effective and comprehensive Model code TR Package Firmly grounded in PhysicsConnected to realityFrom birth to death of the PFUseful and comprehensive outputsDiagnostic reference-many properties, design, scaling & scaling laws, insights & innovations
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