16kOhm (not 1,6kOhm) is the impedance seen by the driver. If I apply 100v pulse, the current drawn from the power supply (and consequently flowing to the cell, because all components are in series) will be 100/16000 = aprox 6,25mA. At resonance, you have current restriction at cell, same effect if you use stainless stell coils instead of copper.
And, as I stated before, less current in the cell means less voltage in the cell, you cannot violate ohms law applying more voltage and having less current, IT WILL ALWAYS BE A LINEAR RELATIONSHIP between voltage and current.
It is the impedance of the self resonance of the coils, or anti-resonance, or parallel resonance, you can call it many names.
Im using a ferrite C core from a TV flyback, the frequency is right, as I`m using only the coils capacitance and inductance to resonante. If you want lower freuquencies, increase the number of turns or use a higher permeability core.
I bought this equpment at a junkyard, they were ready to crush it, and I save it. It worked fine for many years, but last year it stopped working and I didnt had time to open to fix it. It was from a siemens lab as you can see in the front tag.