Status of HCC simulation study

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Status of HCC simulation study

• Katsuya Yonehara
• Accelerator Physics Center, Fermilab

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Particle Motion in Helical Magnet
Y.S. Derbenev and R.P. Johnson, PRSTAB 8, 041002
(2005)
Combined function magnet Solenoid Helical
dipole Helical Quadrupole
Red Reference orbit
Magnet Center
Blue Beam envelope
Dispersive component makes longer path length
for higher momentum particle and shorter path
length for lower momentum particle.
Helical solenoid coils
Repulsive force
Attractive force
3
Basic concept in HS design
V. Kashikhin

• Need to adjust (Bz, b, b) on red dot
• Blue dot and green dot are centers of
• upstream (Coil-1) and
• downstream (Coil-2) HS coils
• Br on red dot is zero
• Bz and b are tuned by the location of
• HS coil
• b is tuned by the coil size

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Expand inner radius of HS coil

• Need to adjust (Bz, b, b)
• Calculate the ratio b/b
• Adjust b/b by primary HS
• and correction HS coils
• Finally tune the Bz by adding
• Solenoid coil

Primary HS coil
300 MHz RF cavity
Solenoid coil
Correction HS coil
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Example result
HCC l1.6 m, k1.0 Primary HS Inner R 460
mm, Outer R 510 mm Current density -74
A/mm2 Correction HS Inner R 150 mm, Outer R
200 mm Current density 208 A/mm2 Solenoid
Inner R 860 mm, Outer R 910 mm Current
density 47 A/mm2
400 MHz RF cavity
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Series of HCCs
1st HCC l2.0 m, k1.0 Primary HS Inner R
650 mm, Outer R 680 mm Current density -69
A/mm2 Correction HS Inner R 250 mm, Outer R
280 mm Current density 414 A/mm2 Solenoid
Inner R 1000 mm, Outer R 1050 mm Current
density -11 A/mm2
bsol -2.7 T, b 0.86 T, b/b -0.84
Cooling factor gt 10,000
bsol -5.3 T, b 1.63 T, b/b -0.86
200 MHz RF
2nd HCC l1.0 m, k1.0 Primary HS Inner R
367 mm, Outer R 397 mm Current density -129
A/mm2 Correction HS Inner R 150 mm, Outer R
180 mm Current density 387 A/mm2 Solenoid
Inner R 600 mm, Outer R 650 mm Current
density -31 A/mm2
400 MHz RF
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Series of HCCs (contd)

• Careful adjustment for initial phase space
• Fake longitudinal reduction at begin of HCC
  disappears

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Difficulties in current design
l 0.4 m k 1.0 bsol -13.2 T b 3.95 T b
-5.64 T/m
RF frequency 1.2 GHz RF radius 0.096 m Inner
radius of primary HS 0.176 m
b becomes positive at inner radius of HS more
than 0.13 m Required huge current density in
correction coil
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Possible solution
Helical Elliptical coil
Add helical conductors surround on primary HS coil
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RF breakdown suppression by high pressurized GH2
in RF cavity
R. Johnson et al, A. Tollestrup, D. Rose

• RF is required to compensate the energy loss
• High pressurized GH2 filled RF cell is
  preferable for HCC
• Suppress dark current ? High field gradient in
  magnetic field
• GH2 can be used as the ionization cooling absorber

805 MHz High Pressurized RF test cell
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Lars Thorndale
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(No Transcript)
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Ansys stress simulation
Ang Lee
At 1500PSI (100atm) SS316 1.25 wall
required Inconel 625 0.75 wall required ASME
pressure vessel code used
Andreas Jansson
MUTAC Meeting 8-10 April 2008
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HS for Cooling Demonstration Experiment
V. Kashikhin, A. Zlobin, M. Lamm, S. Kahn, M.
Lopes
Goals cooling demonstration, HS technology
development Features SSC NbTi cable, Bmax6 T,
coil ID 0.5m, length 10m

• Status conceptual design complete
• solenoid
• matching sections
• Next engineering design
• mechanical structure
• field quality, construction tolerances
• cryostat
• powering and quench protection

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4-coil model Analysis

• Magnetic and mechanical design and analysis
  complete
• 3D field distribution
• 3D stress/strain in coils and mechanical
  structure

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4-coil fabrication status

• Parts
• design complete
• procurement in progress
• Cable
• strand samples were tested
• Practice winding complete
• cable stability and support during hard bend
  winding
• coil size control
• Instrumentation
• development started

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Summary

• Found a solution to embed RF cell in HCC
• Obtain cooling factor gt 10,000 in lt 200 meters
• Mechanical analysis of high pressurized helical
  pipe
• Power and structure of HPRF cell
• Train winding HS coil

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Next to do

• Find effective field correction
• Helical elliptic coil, Helical conductor
• Matching
• HP windows
• Upstream downstream of HCC
• RF structure RF power
• OK with 300 mm Be window
• Investigate traveling wave acceleration
• Test LiH wedge absorber
• Reduce GH2 pressure
• Optional cooling
• Transverse/longitudinal dominant cooling