The trap that we are using is an adaptation of the linear Paul Trap. It has a blade design as shown in the image below.
Figure: RF trap used in our experiments and its cross section with a view of all the electrodes .
An important characteristic of this blade design is that it allows for a larger solid angle of optical access to the ions. This is essential for collection of the ion's fluorescence. The four blade electrodes allow us to radially confine the ions. The endcap electrodes have a small hole to allow axial control of the ions. There are also three cylindrically shaped compensation electrodes around the blades which allow us to adjust and control the micro-motion of the ions.
We use this trap to perform some really cool quantum gates experiments!
 J. Mosca-Toba, "Design of an Imaging System for the State Detection of Trapped Ca ions," Imperial College London, Department of Physics, London, 2018.
 J. Mosca-Toba, "Design of an Imaging System and implementation of Photoionization for a Linear Paul Trap," Imperial College London, Department of Physics, London, 2019.