ADPF spoke cavity cryomodule concept Page: 4 of 8
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&r Cold Stepper Motor
Split Arm Support
FIGURE 3. The R=0.34 helium vessel tuner assembly. A cold motor is used to minimize radial penetrations.
modified Ledford/Wood tuner used for the APT program was adopted . The cavity
stiffeners are used to transfer the tuning load through the helium vessel back to the cavity
where it is balanced by the load on the beam tube. Bellows are used to decouple the beam
tubes from the helium vessel, which is similar to the APT design approach. A cold stepper
motor drives the tuner (similar to TESLA ) though a warm motor with axial drive shaft
is possible. A piezoelectric actuator is used to detune the cavity in < 300 msec.
The use of individual helium vessels limits the volume available for helium inventory.
With its superior cooling properties at 4.5 K, bath cooling of the cavity was selected over
supercritical forced flow. Hence, boiling of the helium is anticipated with the potential for
vapor locking. To cope with space constraints, provide reasonable helium inventory,
reduce vapor locking and improve heat transfer, an open-loop thermosyphon cooling
approach was selected. Fig. 4 shows details of the j=0.34 cryomodule thermosyphon and
analytical predictions for mass flow rates and flow quality . The analysis includes
bellows in the runs between risers. Orifice plates at the bottom of the risers balance the
flows. The reservoir is located in the cryomodule Tee section.
The fixed power coupler is a 75 Q, coaxial, unbiased unit . Couplers are oriented
200 from vertical, with adjacent couplers in a lattice on alternate sides of the module. The
couplers closest to the center Tee section are on the same side of the module. The near
vertical orientation was due to APT tunnel constraints. The alternating-sides coupler
arrangement is necessary to maintain clearance between large WR2300 waveguides (0.584
5.1 cm Tu
15.2 cm Tube 0.61 m
Q / mt 0.75
Q im im
m m2 m3
be 15.2 cm Tube
3.8 cm Orifice
3.3 cm Orifice
ml = 35.3 g/s, Xi
m,2 = 35.2 g/s, x2
All tube 0.165 cm wall m2 = 34.9 g/s, x3
mt = 210.9 g/s
FIGURE 4. Thermosyphon schematic and analytical results for the =0.34 cryomodule.
between risers were included in the analysis but are not shown.
Bellows in the runs
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Kelley, J. P. (John Patrick); Roybal, P. L. (Phillip L.); La Fave, R. P. (Richard P.); Waynert, J. A. (Joseph A.); Schrage, D. L. (Dale L.); Schmierer, E. N. (Eric N.) et al. ADPF spoke cavity cryomodule concept, article, January 1, 2001; United States. (digital.library.unt.edu/ark:/67531/metadc935319/m1/4/: accessed November 20, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.