magnetic intervention dump concepts
DESCRIPTION
Magnetic Intervention Dump Concepts. A. René Raffray UCSD With contributions from: A. E. Robson, D. Rose and J. Sethian HAPL Meeting Santa Fe, NM April 8-9, 2008. Recap on Magnetic Intervention from Last Couple of Meetings. - PowerPoint PPT PresentationTRANSCRIPT
ARR/April 8, 2008 1
Magnetic Intervention Dump Concepts
A. René RaffrayUCSD
With contributions from: A. E. Robson, D. Rose and J. Sethian
HAPL MeetingSanta Fe, NMApril 8-9, 2008
ARR/April 8, 2008 2
Recap on Magnetic Intervention from Last Couple of Meetings
• Magnetic intervention to steer ions away from the chamber to reduce threat (ion implantation + energy deposition) on chamber first wall and provide for longer dry wall chamber armor lifetime
• Ions guided to separate ion dumps away from chamber
• Intriguing possibility of even using liquid walls provided geometry allows for it without unacceptable contamination of main chamber
• Two arrangements recently considered:- Conventional symmetric cusp arrangement with poles and an equatorial ring- Octagonal arrangement (octacusp)
ARR/April 8, 2008 3
2 Magnetic Intervention Concepts Considered Recently
• Conventional symmetric cusp arrangement with poles and an equatorial ring, and a duck bill ion dump configuration- Extremely challenging (if at all
feasible) to accommodate huge ion energy fluxes at poles- Also very difficult to accommodate
footprint and peaking factor of ion fluxes at equatorial ring with dry- armored duck bill ion dumps
• Octagonal arrangement (octacusp)- Ion fluxes require fluid protection in
dump region (e.g. Pb mist)- Gravity works against an upper
liquid wall dump concept- Challenging to design liquid wall dump region to accommodate ion fluxes without contaminating main chamber
Focusing solenoids
Spherical windings
Field lines
ARR/April 8, 2008 4
• 97% of ion energy though annular dump port• Gravity works for us in designing a liquid Pb dump at bottom
New Inverted Martini Glass Cusp Concept (From B. Robson)
ARR/April 8, 2008 5
Better to Use Inverted Burgundy Glass Concept (if possible) to Prevent Direct Line-of-Sight Contamination of Main Chamber
ARR/April 8, 2008 6
Possibility of Using a Liquid Dump Concept without Contaminating main Chamber
• Initial liquid dump concept based on separation of function- Recycled liquid Pb to accommodate ion energy and particle deposition,
including diverted “bleeding” flow for clean-up- Separate coolant for power removal (e.g. Pb-17Li)
• Different liquid Pb configurations considered- All assume Pb pool at bottom and low-temperature condensation trap (<
main chamber wall temperature) - “Waterfall” concept- Mist concept- Liquid film concept (presented here as example)
• Analysis in very early stage- Need to analyze all concepts to get a better understanding and to help in
deciding direction of effort- Need also right analysis tools
ARR/April 8, 2008 7
Assumptions for Calculating Temporal and Spatial Power Deposition in Liquid Pb Pool
• Chamber diameter, D = 10 m
• Annular Pb ion dump pool, 4 m wide and 10 m in average
radius from center line- Pb dump pool area = 250 m2
• Time of flight of ions based on:- Number of transits, ntrans = 6- Opening for annular cusp port as a
fraction of chamber wall area = 0.0975
- 0.0975 of ion energy based on direct flight to liquid Pb dump pool
- 0.9025/6 assumed lost after each of the 6 assumed transits with time of flight based on (itrans x D + Lport)
- To be verified by more detailed calculations (D. Rose)
Chamber Diameter, D = 10 m
Annular ion port opening width = 1.5 m
3.25 m
Pb pool location
Lport=10.5 m
4 m
10 m
ARR/April 8, 2008 8
Pb-17Li CoolantTin ~ 550°C
Pb-17Li Coolant Tin ~ 550°C
Pb-17Li Coolant, Tout ~ 634°C
Pb as ion dump fluid armor
Pb as ion dump fluid armor
Pb Evaporation
Pb Condensation
Gravity-driven creeping flow of thin Pb layer (~2 mm) through and over ~ 2 mm thick SiC/SiC mesh
Pb-17Li coolant flow in SiCf/SiC channels (~5 mm walls and ~5 mm Pb-17Li region)
Liquid Pb pool (~10 mm)
Pb-17Li coolant flow in SiCf/SiC channels (~5 mm walls and ~5 mm Pb-17Li region)
Example Liquid Pb Pool Dump Concept with Gravity-Driven
Creeping Flow through/over SiC/SiC
Mesh
ARR/April 8, 2008 9
Ion Spectra from 367 MJ Target
Total (MJ)X-rays 4.937 (1.34%)Gammas 0.01680 (0.0046%)Neutrons 274.3 (74.72%) Protons 1.763 Deuterons 21.724 Tritons 26.50 3He 0.0777 4He 30.28 12C 6.880 13C 0.08367 Pd 0.1844 Au 0.3607 Pt < 0.000001Total Ions 87.85 (23.93%)Total out 367.1 MJResidual thermal energy (0.03494)Laser Energy Absorbed (2.426)Nuclear Energy Produced 364.7 MJ
ARR/April 8, 2008 10
Attenuation of Ion Spectra By Pb
• 350 MJ target (total ion energy = 87.8 MJ)
0.0x10
0
1.0x10
7
2.0x10
7
3.0x10
7
4.0x10
7
5.0x10
7
6.0x10
7
7.0x10
7
8.0x10
7
9.0x10
7
0.0x10
0
2.0x10
1
4.0x10
1
6.0x10
1
8.0x10
1
1.0x10
2
mg/cm
2
of Pb
Pb liquid density = 11300 kg/m 3
R=5 m; no chamber gas; 367 MJ target
Annular cusp ports, with opening at chamber wall
1.5 m in width and 3.25 m from center-line, and a
port length of 10.5 m
97% of ion energy through annular port
ARR/April 8, 2008 11
Energy of Ions as a Function of Penetration Depth
1x103
1x104
1x105
1x106
1x107
1x108
1x10-7 1x10-6 1x10-5 1x10-4 1x10-3
Penetration Depth (m)
Pb liquid density = 11300 kg/m3
R=5 m; no chamber gas; 367 MJ target
Annular cusp ports, with opening atchamber wall 1.5 m in width and 3.25 mfrom center-line, and a port length of 10.5 m
97% of ion energy through annular port
ARR/April 8, 2008 12
Spatial Ion Energy Deposition in Liquid Pb Ion Dump
1x104
1x105
1x106
1x107
1x108
1x109
1x1010
1x1011
1x1012
1x10-7 1x10-6 1x10-5 1x10-4 1x10-3
Penetration depth (m)
Pb liquid density = 11300 kg/m3
R=5 m; no chamber gas; 367 MJ target
Annular cusp ports, with opening atchamber wall 1.5 m in width and 3.25 mfrom center-line, and a port length of 10.5 m
97% of ion energy through annular port
ARR/April 8, 2008 13
Temporal and Spatial Power Deposition in Liquid Pb Pool
• R = 5 m; no chamber gas; 367 MJ target
• Annular cusp ports, with opening at chamber wall 1.5 m in width and 3.25 m from centerline, and a port length of 10.5 m
• 97% of ion energy through annular port
• Pb liquid density = 11300 kg/m3
ARR/April 8, 2008 14
Temperature and Evaporation History for Liquid Pb Pool
without Vapor Shielding
• Avg Pb-17Li coolant T at back of Pb pool ~ 625 °C
• Pb pool surface T at beginning of cycle = 690 °C
• Total ion energy in annular dump = 85.2 MJ
• From analysis:-Total evaporation energy = 55.2 MJ-Energy to liquid Pb pool ~ 30 MJ
• Large amount of evaporated Pb (~23 m) would provide vapor shielding (see next slide)
0.00E+00
5.00E-06
1.00E-05
1.50E-05
2.00E-05
2.50E-05
1.00E-07 1.00E-06 1.00E-05 1.00E-04 1.00E-03 1.00E-02 1.00E-01 1.00E+00
Time (s)
Evaporated Thickness (m)
Evap, Pb
5.0E+02
1.0E+03
1.5E+03
2.0E+03
2.5E+03
3.0E+03
3.5E+03
4.0E+03
1.0E-07 1.0E-06 1.0E-05 1.0E-04 1.0E-03 1.0E-02 1.0E-01 1.0E+00
Time (s)
Temperature (°C)
TsurfaceT at 6 micronsT at 12 micronsT at 18 micronsT at 24 micronsT at 10 mm (Pb/SiC)
ARR/April 8, 2008 15
Temperature and Evaporation History for Liquid Pb Pool WITH
Vapor Shielding • Avg Pb-17Li coolant T at back of
Pb pool ~ 625 °C
• Total ion energy in annular dump = 85.2 MJ
• From analysis:- Total evaporation energy = 14.5 MJ- Assume energy to liquid Pb pool still ~ 30 MJ (probably much lower) - Then vapor shield energy > ~ 41 MJ
• Smaller amount of evaporated Pb (~6 m) with vapor shielding
• Pb temperature below surface (~12 microns) > surface temp. and > BP (1749°C at SP) indicating possibility of much higher mass loss and vapor shielding and lower energy deposition in Pb dump (need correct analysis tool)
0.00E+00
1.00E-06
2.00E-06
3.00E-06
4.00E-06
5.00E-06
6.00E-06
7.00E-06
1.00E-07 1.00E-06 1.00E-05 1.00E-04 1.00E-03 1.00E-02 1.00E-01 1.00E+00
Time (s)
Evaporated Thickness (m)
Evap, Pb
0.0E+00
5.0E+02
1.0E+03
1.5E+03
2.0E+03
2.5E+03
3.0E+03
3.5E+03
1.0E-07 1.0E-06 1.0E-05 1.0E-04 1.0E-03 1.0E-02 1.0E-01 1.0E+00
Time (s)
Temperature (°C)
TsurfaceT at 6 micronsT at 12 micronsT at 18 micronsT at 24 micronsT at 10 mm (Pb/SiC)
ARR/April 8, 2008 16
Quasi Steady-State Temperature of Pb in Bottom Pool and in Thin Layer Along Port Walls
BOTTOM REGION WITH Pb POOL• Rep rate = 5• Energy flux to Pb in bottom pool = 15 MJ (<30 MJ, rough estimate here)• Pb pool surface area = 250 m2
• Avg. eff. q’’ = 0.6 MW/m2
• T through 1 cm Pb (k = 15 W/m-K) = 199°C• T through 5 mm SiCf/SiC structure (k = 15 W/m-K) =100°C• Pb-17Li temperature at entry to Pb pool ~ 619°C• Exit Pb-17Li temperature ~ 634°C• Max/Avg/Min Pb surface temperature in pool = 969/962/954°C
PORT REGION WITH Pb FILM• Rep rate = 5• Energy flux on condensing surface in port = 70 MJ• Condensing surface area = 1319 m2
• Avg. eff. q’’ = 0.21 MW/m2
• T through 2 mm Pb (k = 15 W/m-K) = 35°C• T through 5 mm SiC/SiC structure + 2 mm mesh (k = 15 W/m-K) = 124°C• Inlet Pb-17Li temperature ~ 550°C• Pb-17Li temperature at exit of Pb film ~ 619°C• Max/Avg/Min Pb surface temperature in port = 812/777/743°C
ARR/April 8, 2008 17
Pb Vapor Pressure as a Function of Temperature
1.0E-08
1.0E-06
1.0E-04
1.0E-02
1.0E+00
1.0E+02
1.0E+04
1.0E+06
0 500 1000 1500 2000 2500
Temperature (K)
Pb Vapor Pressure (Pa)
1.0E-16
1.0E-14
1.0E-12
1.0E-10
1.0E-08
1.0E-06
1.0E-04
1.0E-02
1.0E+00
Fractional Density (based on
Pb Liquid density)
• Liquid Pb density = 11,300 kg/m3
ARR/April 8, 2008 18
Film Condensation in Ion Dump Port
jnet = net condensation flux (kg/m2-s)M = molecular weight (kg/kmol)R = Universal gas constant (J/kml-K)= correction factor for vapor velocity towards film cecondensation and evaporation coefficientsPg, Tg = vapor pressure (Pa) and temperature (K)Pf, Tf = saturation pressure (Pa) and temperature (K) of film
Example Scoping Calculations for Annular Dump Port
• Liquid Pb as film material
• Surface Condensation Area = 1319 m2
• Port Volume = 2639 m3
• ce= 0.5
•
• Pb evaporated thickness (~10 microns) and vapor temperature (~2500°C) estimated from RACLETTE results
• Characteristic condensation time estimated based on vapor mass in chamber and condensation rate corresponding to assumed conditions
jcond
jevap
TfPg Tg
jnet=MR2π
⎛ ⎝ ⎜ ⎞
⎠ ⎟
0.5Γσc
Pg
Tg0.5
−σePf
T f0.5
⎡
⎣
⎢ ⎢
⎤
⎦
⎥ ⎥
ARR/April 8, 2008 19
Scoping Analysis of Pb Condensation in Example
Annular Port Dump Region
• Characteristic condensation time fast, ~0.03 s, over a large range of condensation surface temperature (time to condense all Pb vapor at given conditions)
Characteristic Annular Cusp Port Condensation Time as a Function of Surface Condensation Temperature
1.0E-02
3.0E-02
5.0E-02
7.0E-02
9.0E-02
1.1E-01
1.3E-01
500 600 700 800 900 1000 1100 1200
Condensation Surface Temperature (°C)
Chracteristic Condensation
Time (s)
Condensation Rate as a Function of Surface Condensation Temperature
1.0E-02
6.0E-02
1.1E-01
1.6E-01
2.1E-01
2.6E-01
3.1E-01
3.6E-01
4.1E-01
500 600 700 800 900 1000 1100 1200
Condensation Surface Temperature (°C)
Condensation Rate (kg/m2-s)
ARR/April 8, 2008 20
Rough Estimate of Integrated Condensation Assuming Linear Decrease in Vapor Temperature
• Simple integration of condensation rate as a function of changing conditions assuming linear decrease in vapor temperature (from a maximum temp. of 2500°C to the condensation surface temperature)- Faster return to vapor pressure for higher higher condensation surface temperature
and for longer time between shots (lower rep rate)- For a rep rate of 5, results indicates return to vapor pressure for a surface
temperature of ~720°C (0.96 Pa)
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
1.0E+01
1.0E+02
1.0E+03
1.0E+04
1.0E+05
500 600 700 800 900 1000 1100
Condensation Surface Temperature (°C)
Final Pvap/Psat
Time between shots = 0.1 s
Time between shots = 0.2 s
Time between shots = 0.5 s
ARR/April 8, 2008 21
Questions needed to be addressed include:- Better characterization of behavior of Pb pool under ion energy deposition- Ion energy attenuation in Pb vapor and radiation analysis needed to
characterize energy deposition on port walls and whether a protective film is needed
- Can the port geometry and coolant hardware be placed so as not to interfere with the laser beams?
- Does the configuration provide enough geometry restriction and condensation trapping to prevent unacceptable main chamber Pb contamination?
- Would a thick liquid wall or a mist configuration provide better protection against contamination of main chamber?
- How to design the dumps to accommodate the polar ion fluxes (~3%)?
MORE WORK NEEDED AND COMMENTS ARE MOST WELCOME
Proposed Inverted Burgundy Glass Concept Encouraging but More Analysis Needed to Determine Feasibility and
Attractiveness