DEVELOPMENT OF SSR2 FOCUSING LENSES FOR PIP-II (Design ... · Main coil inner radius 28.75 mm 3....
Transcript of DEVELOPMENT OF SSR2 FOCUSING LENSES FOR PIP-II (Design ... · Main coil inner radius 28.75 mm 3....
DEVELOPMENT OF SSR2 FOCUSING LENSES FOR PIP-II (Design Studies for Conduction Cooled Magnet)
Electromagnetic Application Section
Electromagnetic Applications & Instrumentation Division
Team members: Kumud Singh, Janvin Itteera, Mahima, R R Singh , Rajesh Chimurkar, Rajesh Jalan & Sanjay
Malhotra
February 17, 2020 IIFC Magnet meeting presentation - Kumud Singh | SSR2 lenses For PIP-II
Vacuum pumps
Cryostat housing magnet
Electronics rack
Power diode connected in shunt with magnet
• Functional requirement specification
• Electromagnetic design
• Bucking coil optimization
• Corrector coil design
• Static thermal analysis
• Operating design margin
• Fringe field at cavity surface
• Nominal Operating Design Margin
• Thermal analysis
• Quench design
• Conclusion & Summary
Outline
February 17, 2020 IIFC Magnet meeting presentation - Kumud Singh | SSR2 lenses For PIP-II
Functional Requirement Specifications (FRS)
Parameters SSR1 Earlier
Specifications
SSR2 Earlier
specifications
SSR1/SSR2 New
specification
Focusing Strength 4.0 T2m 5.0 T2m 4.5 T2m
Bending strength of Dipole correctors 2.5 mT-m 5 mT-m 5 mT-m
Beam pipe aperture 30mm 40 mm 40 mm
Uncertainty in the location of magnetic
axis w.r.t Reference points (Transverse
and angular alignment)
<0.1 mm RMS
<0.5mrad RMS
<0.1mm RMS
<0.5 mrad RMS
<0.1mm RMS
<0.5 mrad RMS
Effective length of solenoid (FWHM) Insertion length of
Max 160mm
<15 cm Insertion length of
Max 180mm
Active magnetic shielding requirements 0.5Q0 criterion
-
-
Maximum current in the solenoid 100A 100A 100A
Maximum current in the dipole
correctors
50A 50A 50 A
February 17, 2020 IIFC Magnet meeting presentation - Kumud Singh | SSR2 lenses For PIP-II
Electromagnetic Design
Sr. no Parameter Value Unit
1. Length of solenoid coils in the lens 120 mm
2. Main coil inner radius 28.75 mm
3. Main coil outer radius 62.5 mm
4. Strand diameter (bare) 0.4 mm
5. Winding fill factor 0.65
6. Number of turns in the main coil ~13500
Sr. no Parameter Value Unit
1. Length of Bucking Coils 55 mm
2. Bucking coil inner radius 85 mm
3. Bucking Coil outer radius 95 mm
4. Strand diameter 0.4 mm
5. Bucking Coil Z location* 32.5 mm
6. Winding fill factor 0.65
7. Number of turns in the Bucking coil ~1833
Objective function :
𝐵𝑧2 . 𝑑𝑧 ≥ 5 T2m
Minimize 𝐵. 𝑑𝑙 𝑟=0.3
𝑟=0 at z= 0.5m
Constraints: 𝐵𝑧∗𝑑𝑧
𝐵0 ≤ 150 cm
I exc < 100A
Optimization Parameters:
Nmain, OR main, IR main , OR main
NBC, L BC , Z center-BC
February 17, 2020 IIFC Magnet meeting presentation - Kumud Singh | SSR2 lenses For PIP-II
Electromagnetic Design… continued
B field vs axial distance plot
February 17, 2020 IIFC Magnet meeting presentation - Kumud Singh | SSR2 lenses For PIP-II
Electromagnetic design … continued
FWHM = 134 mm
Zonal plot of Magnetic field at the magnet center (field homogeneity 1.4%)
B field plot and B2 Plot along the axial length (Focusing strength of 4.736 T2m) and FWHM of 134cm
February 17, 2020 IIFC Magnet meeting presentation - Kumud Singh | SSR2 lenses For PIP-II
Dipole corrector design
Zonal field plot of dipole field in the magnet aperture
February 17, 2020 IIFC Magnet meeting presentation - Kumud Singh | SSR2 lenses For PIP-II
Dipole Corrector design
Magnetic Field (Bx or By) plot in the lens aperture
at various radial locations when corrector coils
are connected as skew quadrupole
Bx field plot vs transverse distance in magnet
aperture (Gradient = 2.59T/m)
February 17, 2020 IIFC Magnet meeting presentation - Kumud Singh | SSR2 lenses For PIP-II
Electronics rack
Power diode connected in shunt with magnet
2D sketch of magnet assembly
Note : Not to scale
February 17, 2020 IIFC Magnet meeting presentation - Kumud Singh | SSR2 lenses For PIP-II
Electronics rack
Power diode connected in shunt with magnet
Magnet Model & 2D Drawing
February 17, 2020 IIFC Magnet meeting presentation - Kumud Singh | SSR2 lenses For PIP-II
Bucking coil optimization
B field vs axial distance plot for different cases of Bucking coil dimensions
February 17, 2020 IIFC Magnet meeting presentation - Kumud Singh | SSR2 lenses For PIP-II
Vacuum pumps Electronics rack
Power diode connected in shunt with magnet
Superconducting Wire strand material properties
• All conduction cooled magnets are proposed to be wound using round 0.4 bare diameter /0.44
mm insulated strand (NbTi/ copper matrix 1:1.3 Sc:Cu Ratio) from LUVATA (OK636).
𝐵𝐶𝑇 = 𝐵𝑐0 1 −𝑇
𝑇𝑐0
2
The ratio of the maximum current density in the superconductor at any magnetic field and
temperature to that at B = 5 T and T = 4.2 K can be found using the expression given below:
Jc(B,T) / Jc(5 T, 4.2 K)= C0/B∙bα∙(1-b)β∙(1-tn)γ
Where, C0 = 28.4 T, α = 0.80, β = 0.89, and γ = 1.87.
Bare Wire
Dia
Filament
Diameter
Cu/Sc Ratio Filament
twist pitch
RRR Ic @ 4 T ,
4.2K
Ic @ 5 T
, 4.2K
Ic @ 7 T ,
4.2K
Ic @ 8 T ,
4.2K
0.4mm 10.5 μm 1.3:1 50-100mm Min 60 180 A 140A 80A 55A
February 17, 2020 IIFC Magnet meeting presentation - Kumud Singh | SSR2 lenses For PIP-II
Vacuum pumps Electronics rack
Power diode connected in shunt with magnet
Nominal Operating Design Margin
3K
February 17, 2020 IIFC Magnet meeting presentation - Kumud Singh | SSR2 lenses For PIP-II
Fringe field on cavity surface
Φtr= 2μ0Φ0
(Rs∙ ξ02)
* f∙V
(ΛQ0)
*(1−η)
η
μ0=4π∙10-7H/m ; Φ0=2∙10-15Wb
ξ0=3.9∙10-8 m is the coherent length in Nb, f is
the frequency of the cavity,
Rs is the surface resistance of Nb at this
frequency,
V is the volume of the cavity,
Λ = Magnetic energy density at the location of the quenchAverage energy density in the cavity
Completely defined by the properties
of superconducting material Cavity Specific
Acceptable degree of
degradation η with
allowed amount of the
trapped flux.
Surface integral / line integral at the maximum
magnetic energy density location needs to be
minimized during the design of bucking coil
Placement of a focusing lens inside the SSR cryomodule
February 17, 2020 IIFC Magnet meeting presentation - Kumud Singh | SSR2 lenses For PIP-II
Fringe field on cavity surface for two probable choices of Bucking coil
February 17, 2020 IIFC Magnet meeting presentation - Kumud Singh | SSR2 lenses For PIP-II
Fringe field on cavity surface for two probable choices of Bucking coil
So optimized design
is chosen to be BC
IR = 85mm
OR=95mm
Length = 55mm
Z center = 32.5mm
February 17, 2020 IIFC Magnet meeting presentation - Kumud Singh | SSR2 lenses For PIP-II
Thermal design (Static thermal simulations)
3D model for thermal simulation
Half model with highlighted heat flux boundary condition
Heat Sink – Fixed temp 2.15K
Heat Flux = 𝟏𝑾
(𝟐∗𝝅∗𝒓∗𝒉)
February 17, 2020 IIFC Magnet meeting presentation - Kumud Singh | SSR2 lenses For PIP-II
Vacuum pumps Electronics rack
Power diode connected in shunt with magnet
Static Thermal Analysis (no EDM cut in beam pipe)
Case – a (SS Bobbin 0.2mm plating thickness)
1W heat on beam pipe
Heat sink face anchored to 2K
February 17, 2020 IIFC Magnet meeting presentation - Kumud Singh | SSR2 lenses For PIP-II
Vacuum pumps Electronics rack
Power diode connected in shunt with magnet
Static Thermal Analysis … continued (with EDM cut to isolate beam load)
Case – b (SS –bobbin 0.2mm plating thickness) EDM cut on beam pipe
February 17, 2020 IIFC Magnet meeting presentation - Kumud Singh | SSR2 lenses For PIP-II
Vacuum pumps Electronics rack
Power diode connected in shunt with magnet
Static Thermal Analysis … peak temperature in coils for case 2
Main coil Dipole Corrector coil Bucking coil
February 17, 2020 IIFC Magnet meeting presentation - Kumud Singh | SSR2 lenses For PIP-II
Quench Design
+ PS -
V Tap1 V Tap2 V Tap3 V Tap4
Quench Protection by passive
diodes
Differential Voltage between
Main coil 1 and main coil 2 can
be sensed to detect Quench
To reduce noise, resistor can be
used in series
Two voltage taps can be used
per pair of Corrector coil also
BC coil1 MC coil1 MC coil2 BC coil1
February 17, 2020 IIFC Magnet meeting presentation - Kumud Singh | SSR2 lenses For PIP-II
Vacuum pumps Electronics rack
Power diode connected in shunt with magnet
Quench Design (Quench initiated in Main coil)
At t = 0s At t = 0.01s At t = 0.1s At t = 0.4s
At t = 5s
At t = 20s
Flux initiated by
1W of heat
deposition at peak
B field location
February 17, 2020 IIFC Magnet meeting presentation - Kumud Singh | SSR2 lenses For PIP-II
Peak temperature and voltage in coil
Peak Voltage Current Resistance
February 17, 2020 IIFC Magnet meeting presentation - Kumud Singh | SSR2 lenses For PIP-II
B field level at Current lead location
Peak field of 0.04T at 150mm
away from magnet axis
February 17, 2020 IIFC Magnet meeting presentation - Kumud Singh | SSR2 lenses For PIP-II
Vacuum pumps Electronics rack
Power diode connected in shunt with magnet
Conclusions and summary
• Magnet design has been completed and the design values meet the
requirements stated in FRS
• Quench initiated in Bucking coils results to be compiled . (Transient) Quench
simulations are pending. This is to include heating due to eddy currents.
• Current lead engineering design to be included in FDR.
• Manufacturing drawings initiated.
• BPM interface and Cryomodule interface required to complete manufacturing
drawings.
Thank You for your kind attention
February 17, 2020 IIFC Magnet meeting presentation - Kumud Singh | SSR2 lenses For PIP-II