High Gain and Frequency Ultra-Stable Integrators for ICC and Long Pulse ITER Applications

In modern fusion concepts, inductive pickup loops continue to be one of the primary magnetic diagnostics. This is due to their simple construction, ease of use, and durability, especially when compared to other methods of determining magnetic profiles. Inductive pickup loops are capable of extremely high bandwidths, allowing for the measurements of both high frequency magnetic perturbations as well as the slower field profiles associated with the more steady confinement. To convert the direct voltage measurements from the inductive pickup loop to a meaningful measurement of magnetic field, an integration of the loop voltage must be conducted. In principle a direct integration of the signal should not pose a significant challenge, but in practice several factors make the integration difficult, especially when there are many orders of magnitude difference between the fast and slow magnetic signals. The challenges can broadly be grouped into three general areas; input offset errors, dynamic bandwidth resolution, and long term stability. To address this problem, Eagle Harbor Technologies proposes to transfer and upgrade integrators developed at the University of Washington Redmond Plasma Physics Lab (RPPL) with prior DOE funding. These integrators have a demonstrated utility within the Innovative Confinement Community (ICC) community for having high gain and frequency ultra-stable operation. The proposed work seeks to modify the existing design to provide an ultra-stable integrator system for long pulse ITER and burning plasma applications, as well as to integrate the system into a low cost form factor that will be compatible with several off the shelf data acquisition systems. Commercial Applications and Other Benefits: There is a demonstrated need for configurable high gain, ultra stable integrators within the fusion science and high energy physics communities. These communities will provide a commercial market for the integrators, especially if they are compatible with standard off the shelf data acquisition systems. At this point there is no commercial option for a high quality low cost integrator system, and most laboratories are forced to develop custom integrators; a costly and time intensive endeavor. Other potential commercial applications include feedback and control systems for semi-conductor processing and magnetic sensing in some aerospace and space physics applications.