For the reference BPMs and BPM designs we have now

1
For the reference BPMs and BPM designs we have
now

• A. Liapine

Most of the pictures can be scaled to a bigger
size if needed!
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NanoBPMs at ATF
KEK BPMs on flexure piezo movers
BINP BPMs in SLAC/LLNL frame
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The two existing BPMs
BINP
KEK
No info on BINP couplers except they are using
electric coupling and they are tapered
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KEK BPM v.1.0
Refer also to KEK_cavity_BPM_test_cell.pdf (test
cavity sketch) and KEK_BPM3_mcd.pdf (seemingly
the final design)
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KEK BPM test model feedthrough
Note that initially the pin length of the
feedthrough was much smaller than it is in the
final design. It was set up experimentally.
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KEK BPM simulations

• Estimation of the symmetric mode residual signal
• 40 µm of the equivalent signal for the perfect
  structure
• 60-70 µm for an extreme asymmetric case 0.5
  mm shift of the coupler/coupler components
• We have to be careful about the details

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ATF2 Q-BPM design

• Successor of previous designs
• Longitudinal design
• 4-coupler symmetrical structure
• Beam pipe diameter increased to 20 mm to meet
  the ATF2 beam optics requirements
• Increased coupling for a higher sensitivity
• Dipole mode frequency 6426 MHz (harmonic of the
  bunch repetition frequency)

Symmetric mode leakage Leakage is less than
computation error for the perfect
structure Introducing asymmetries (Slot wg
feedthrough shifted by 0.5 mm, 0.2 mm meshstep)
we get a signal equivalent to 10 µm offset
Sensitivity to the incline component 7 µm/mrad
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Basic parameters of the BPMs
Q08600 used for calculation, elsewhere Q08180
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BINP cavities what is simulated
parameters of the main cavity define(R0,
27.06e-3) Cavity radius define(L, 12e-3)
Cavity length define(a, 9e-3) Beam pipe
radius parameters of output couplers
define(WgW, 30e-3) Width of coupler
define(WgH, 4e-3) Starting height of coupler
define(WgL, 30e-3) Coupler length define(COff,
13.75e-3) Coupler offset from the z axis
define(Wall, 1e-3) Coupler offset from the
cavity parameters of coupling slots
define(SlW, 12e-3) Width of slot define(SlH,
1.5e-3) Height of slot define(SlCOff,
20.3e-3) Slot offset from the z axis
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KEK cavities what is simulated
parameters of the main cavity define(R0,
26.85e-3) Cavity radius define(L, 12e-3)
Cavity length define(a, 8e-3) Beam pipe
radius parameters of output couplers
define(WgW, 27.5e-3) Width of coupler
define(WgH, 7.5e-3) Height of coupler
define(TWgH, 4e-3) Initial height of the
tapered part define(WgL, 40e-3) Coupler
length define(COff, 13.75e-3) Coupler offset
from the z axis define(Wall, 1e-3) Coupler
offset from the cavity parameters of the
round part define(Rround, 26.5e-3) Inner
radius of the round part define(alpha,
30/180_at_pi) Sector angle of the round part
parameters of the feedthrough define(Rout,
2.05e-3) Outer cylinder radius define(Lant,
11.75e-3) Antenna pin's length define(Rin,
0.9e-3) Inner conductor's radius define(Lcoax,
20e-3) Coaxial "cable" length parameters of
coupling slots define(SlW, 11.5e-3) Width of
slot define(SlH, 2.5e-3) Height of slot
define(SlCOff, 20.3e-3) Slot offset from the z
axis