Elegant users forum

Hello,

I am doing some studies using an RFDF element. I notice there is a big difference in the plot of Cy against PHASE (or equivalently TIME_OFFSET) when N_KICKS>1 compared to when N_KICKS=1. In the latter case, I obtain a sin curve as expected; in the former I obtain a highly distorted sin curve. This effect is magnified with higher VOLTAGE and greater L. Do you know what is causing this effect? It happens for very basic settings, including for single-particle tracking. elegant files and a plot attached.

Thanks in advance.

Daniel,

The reason for this odd behavior is that the deflector you are simulating is quite strong (30 MeV) and long (0.5m), while the beam is at relatively low energy (50 MeV). This results in a significant change in vertical coordinate inside the deflector, so the longitudinal component of the field comes into play. The momentum of the beam is changed significantly, which results in distortion of the deflection.

You can test this by, for example, trying a much more energetic beam. In that case, you'll see the expected sinusoidal deflection.

You can also cross-check with the RFTM110 element, which implements a pure TM110-mode deflector (this has its own deficiencies, as described in the manual).

--Michael