ATST Near-IR spectropolarimeter

The development of new solar IR instrumentation in the past decade had opened new windows of opportunity for solar physics research which were not accessible before. Many spectral lines in the near-IR wavelength range from 1 to 2 microns offer powerful diagnostics for the study of solar magnetism in the photosphere, the chromosphere, and the corona. Significant progress and breakthroughs were made in areas such as the generation of weak background magnetic fields by small-scale surface dynamos, the physics of the sunspot, and the direct measurement of magnetic fields in the corona. The combination of these new IR diagnostics tools, and the unprecedented 4-meter aperture and versatile photospheric and coronal capabilities of the Advanced Technology Solar Telescope (ATST), will greatly enhance our capability to study the Sun. It further promises breakthrough observations that can help to resolve many of the long-standing mysteries of solar physics. The instruments for the ATST will need to accommodate a broad range, of science subjects, each with its unique observational requirements. This paper examine the near-IR instrumentation required to achieve the ATST science goals, and present conceptual designs of a near-IR SpectroPolarimeter (NIRSP) aimed at addressing the new challenges of observational solar physics brought upon by the ATST.