The National Spherical Torus Experiment (NSTX) has as an integral part of its mission the assessment of the physics that defines its operating space with respect to MHD stability and confinement, and the development of tools to expand that operating space. Through the efforts of an international collaborative team, the NSTX program has adopted as a central theme that it serves the plasma physics community best when it is focusing on physics questions that are best highlighted by virtue of its unique attributes as compared to other magnetic confinement configurations. With respect to the goals of the CMPD, these attributes include the capability of achieving local beta values of many tens of percent and approaching unity on a routine basis. In such plasmas, electromagnetic effects can become dominant in governing the turbulence characteristics.

This fact combines with theory work that preceded NSTX and GS2 simulations based on data from measured NSTX profiles in high beta plasmas to motivate the present research plan regarding microturbulence studies. First, it is suggested in both studies that long wavelength (ion scale) turbulence is either stable or easily suppressed by ExB flow shear in many cases. Also, these studies indicate that short wavelength (electron scale) turbulence may dominate the transport. To explore these predictions, the NSTX program has in place a correlation reflectometer capable of long wavelength turbulence measurements that can penetrate into the confinement zone of many NSTX plasmas. Planned for deployment in the first year of the life of this Center is a high k scattering system capable of measuring the spectral characteristics of radial wavenumbers in selected spatial locations. Finally, pending support for developing proposals, the NSTX program looks forward to the deployment of an exciting capability of spatially imaging the radial and poloidal components of turbulence ranging from the ion to electron scales.