Fig. 6
From: Fabrication of ion-trap electrodes by self-terminated electrochemical etching
The current density versus voltage curve for electrochemical etching the tungsten rods (0.5 mm diameter and 40 mm immersion depth). The blue curve is the average current density versus the etching voltage. The etching process are divided into four zones. Zone I shows very rough surface and Zone II shows a transition stage where the surface evolves from rough to smooth. Zone III is our targeting region where the tungsten electrodes show very smooth surfaces after etching. In Zone IV, the electrolyte solution begins to breakdown and fluid turbulence appears