Columbia Stellarator eXperiment (CSX)

The Columbia Stellarator eXperiment (CSX) is set to repurpose the Columbia Non-neutral Torus (CNT) into a superconducting, quasi-symmetric stellarator in order to test novel stellarator geometries and their intersection with high-temperature superconducting magnet technologies.

Columbia Non-Neutral Torus

Stellarators, given their steady-state operation, hold particular promise for a sustainable fusion energy system. Their potential has been further elevated by the advent of high-temperature superconductors (HTS), which allows for nearly-zero resistance magnets to operate at a higher magnetic fields and temperatures. HTS magnet technology greatly boosts system performance as fusion power is proportional to the magnetic field strength to the fourth power (B4). Adding another layer of promise is the concept of quasi-symmetry, a type of stellarator configuration that significantly increases particle confinement through optimal shaping. This project seeks to leverage both quasi-symmetry and HTS magnets to make a next-generation university-scale stellarator device.

The CSX device will consist of four coils, two of which are interlocking, non-planar, superconducting coils capable of generating a magnetic field up to 1 Tesla. These superconducting coils incorporate a 3D-printed metal 'bobbin' that are designed, strain-optimized, and assembled in-house. They will be layered with multiple winds of HTS, solder-potted for enhanced structural integrity, and encased within a cryostat for radiative shielding. The coil design leverages advanced winding techniques, low-resistance joint connections, and a series of cold heads for efficient cooling. These coils will live in the 1.5 m diameter vacuum vessel that currently houses the CNT and will be heated by a 10 kW 2.24 GHz magnetron. Experimental efforts, led by Dr. Carlos Paz-Soldan, are currently developing a scaled-down prototype that mirrors the main design's materials and procedures. In parallel, Dr. Elizabeth Paul leads the computation and theory team, which is refining the design of the full-sized coils and optimizing their resulting plasma boundaries.