  Use of a traveling wave (TW) accelerating structure with a small phase
advance per cell instead of standing wave may provide a significant increase of
accelerating gradient in a superconducting linear accelerator. The TW section
achieves an accelerating gradient 1.2-1.4 larger than TESLA-shaped standing
wave cavities for the same surface electric and magnetic fields. Recent tests
of an L-band single-cell cavity with a waveguide feedback demonstrated an
accelerating gradient comparable to the gradient in a single-cell ILC-type
cavity from the same manufacturer. This article presents the next stage of the
3- cell TW resonance ring development which will be tested in the traveling
wave regime. The main simulation results of the microphonics and Lorentz Force
Detuning (LFD) are also considered.
