I was recently experimenting with a full-bridge exciter, that can drive current in both directions through the wire.

The circuit is more complicated but has the advantage  that it produces good torsion waves with lower voltages. The circuit works best with short pulse durations 1 us (C3=C6=500pF). Actually I have R17=0 Ohms.

With short excitation pulses  only one wavelet is triggered and the signal becomes much clearer.