Structure of Edge Turbulence in the HSX Stellarator

The magnetic field of HSX has a unique helical quasisymmetry, which can be broken by a set of auxiliary field coils. Hydrogen plasmas, produced by up to 130\,kW of ECRH power at 5\,kG, exhibit turbulent behavior which is diagnosed by a 16-pin Langmuir probe moved radially in the plasma, while a reference probe stays fixed in space. Measurements of plasma density and potential are processed with correlation analysis and conditional sampling to find the structure of particle transport events (``blob'') at the plasma edge ($r/a > 0.6$). The density-potential crossphases are used to classify the underlying instabilities (i.e. drift wave vs. interchange.) First results from inside the separatrix show blobs with 2--2.5\,cm diameter moving along with the bulk plasma rotation. The crossphase is small, hinting at drift wave dynamics. When a strong radial electric field is imposed on the plasma (via a bias probe), the radial correlation length is halved and the poloidal $E\times B$ rotation is increased.