RF design of RT CH cavities.

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RF design of RT CH cavities.

• Gennady Romanov

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New set of 16 RT cavities is ready
Cavity 16, ß0.142, 370 mm wall-to-wall
Cavity 1, ß0.075, 177 mm wall-to-wall
Whats new new total number of cavities, new
geometrical betas, new aperture of 18 mm, switch
to 4 spokes after 4th cavity.
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Pcopper 280 kW
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Mechanical details. Tolerances.
Length 0.025 mm OD 0.05 mm
- 0.0 mm Rblend 0.0 mm - 0.05
mm 0.1 mm everywhere
Roughness of 1 1.5 microns for spokes is
required to reduce losses and probability of
sparks
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Mechanical details. Blending of spokes.
Radius of blending is 5 mm for all parts of
spokes and for all cavities. Its enough for
smooth distribution of losses at least for cavity
1. RF models do not have round corners. The
error is about (-0.5) MHz for cavity 1, which
can be compensated by reduction of cavity radius
by 1 mm. After all mechanical details are known
(size and shape of base is another example) all
possible errors will be checked and compensated
if needed.
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Mechanical details. Double end walls.
May be we will need additional vent holes in
copper end wall for better vacuum conductivity.
Current estimation without additional vent holes
(AndersonRistori) is a pressure of 710-8 Torr
achievable in a few hours . Appropriate places
for the holes are in the minimums of surface
current.
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Mechanical details. Double end walls.
The holes (semicircles) with radius up to 5 cm do
not disturb noticeably field distribution and
operating frequency.
! Resonant frequency of volume between walls is
580-670 MHz.