Experimental study on ion polarization drift dynamics during fast guide field magnetic reconnection in MRX

We report the detection of ion polarization drift and its effects during fast guide field magnetic reconnection in the two-fluid regime. The normalized guide field, b_gn=b_g/b_up is held at 0.7, where b_g is the guide field at the X-point and b_up is the upstream reconnecting field. The projection of the measured ion flow along the perpendicular electric field E_⊥ is highly compressive and consistent with the measured quadrupolar density variation. These results are consistent with theoretical and numerical predictions [Kleva et al. Phys. Plasmas. 1995]. E_⊥ is observed to transfer a significant amount of magnetic energy to ions in regions with enhanced plasma density, suggesting that the ion polarization drift energizes ions by compression. A limited set of ion temperature measurements show a higher ion temperature near a location where E_⊥ is observed to transfer a significant amount of energy to ions. A study of the energy conversion process shows that the parallel electric field energizes electrons in and around the electron diffusion region (EDR). Away from the EDR, the electrons are found to work against E_⊥, losing energy to ions.