704 MHz Cavity Design

Rama Calaga
Brookhaven National Lab
Files Updated: Feb 5, 2010


Superconducting RF technology in the 700 MHz frequency range is of increasing interest for high average current electron and high intensity proton beams. The key challenge is to develop a multi-cell cavity with state-of-the-art accelerating gradient while providing strong higher order mode (HOM) damping and efficient removal of the HOM power. A five-cell cavity was designed, fabricated and tested to 20 MV/m which served as the original prototype for the electron cooling project (BNL I). The experience led to improvements geared for longer LINACS by lowering the peak magnetic fields and mechanical stifness of the design which evolved in the next generation (BNL II). Details of the 2nd generation design is of the main focus with correspoding comparisons to the orginal design.


BNL II - SPL Design

Fudamental Mode (Mid & End cells)
Higher Order Modes
Fundamental Power Coupler & Kicks
Transition Section, HOM Loops & Bellows
Mehanical & Thermal Analysis
Mechanical Specifications & Tuner
Cavity Treatment & Testing
Cryogenics, Vacuum & Interfaces
BNL I Design (Old)
SPL, beta=1.0 ESS, beta=0.75 ESS, Beta=0.63 ESS, beta=0.83 ESS, Beta=0.67 ESS, Beta=0.65
Mid-Cell End-Cell Mid-Cell End-Cell Mid-Cell End-Cell Mid-Cell End-Cell Mid-Cell End-Cell Mid-Cell End-Cell
Frequency [MHz] 704 704 704 704 704 704 704 704 704 704 704 704
Iris Radius [cm] 7.5 7.5 6.2 6.2 5.5 5.5 7.8 7.0 5.8 5.8 5.8 5.65
Cavity Wall Angle [deg] 14 14 6.0 9.3 6.0 7.2 10.0 14.5 6.0 7.4 6.0 8.4
Equatorial Ellipse Ratio 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0
Iris Ellipse Ratio 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2
Cavity Wall to Iris Plane [cm] 1.7 1.7 1.5 1.5 1.3 1.3 1.5 1.5 1.3 1.3 1.3 1.35
Half Cell Length [cm] 10.65 10.5 7.98 7.98 6.7095 6.7095 8.832 8.832 7.128 7.128 7.128 6.916
Eq. Height [cm] 19.3728 19.2375 - - 18.7202 18.7202 - - - - - 18.753
Superfish File & Beta [v/c] SPL, beta=1.0 ESS, beta=0.75 ESS, beta=0.63 ESS, beta=0.83 ESS, beta=0.67 ESS, beta=0.65
ILC Type & Beta [v/c] ILC, beta=1.0 ILC, beta=0.84 ILC, beta=0.74


MAFIA File BNL II Design
ABCI File:BNL2, BNL3
Microwave Studio File
Engineering Format (SAT, STL)

send e-mail to: rcalaga [at] bnl.gov