3-D simulation of hollow-beam helix TWTs

We present physics studies of hollow-beam helix TWTs using 3D particle-in-cell simulation methods. Modern desktop computing power now permits us to perform true-geometry simulation of the helix slow-wave device with near-realistic tube length, although with course resolution of the helix wire element. One important benefit of true-geometry simulation is the implicit inclusion of the strong backward-wave physics at a wavelength corresponding to twice the pitch. These 3-D simulations are intended to verify and calibrate this and other known 3-D TWT behavior.