Bipolar programmable current supply for superconducting nuclear magnetic resonance magnets

Jaakko Koivuniemi*, R. Luusalo, P. Hakonen

*Corresponding author for this work

    Research output: Contribution to journalArticleScientificpeer-review

    3 Citations (Scopus)
    34 Downloads (Pure)


    In high resolution continuous-wave nuclear magnetic resonance (NMR) work well-reproducible, linear sweeps of current are needed. We have developed a microcontroller based programmable current supply, tested with superconducting magnets with inductance of 10 mH and 10 H. We achieved a resolution and noise of 4 ppm. The supply has an internal sweep with programmable ramping rate and a possibility for remote operation from a computer with either GPIB or RS232 interface. It is based on an 18-bit D/A converter. The maximum output current is ±10A, the sweep rate can be set between 1 μA/s-140 mA/s, and the maximum output voltage is ±2.5V. In work at ultralow temperatures, especially in superconducting quantum interference device NMR, all rf interference to the experiment should be avoided. One of the sources of this kind of unwanted input is the digital switching noise of fast logic devices. We discuss this problem in the context of our design.

    Original languageEnglish
    Pages (from-to)3418-3425
    Number of pages8
    JournalReview of Scientific Instruments
    Issue number9
    Publication statusPublished - 1998
    MoE publication typeA1 Journal article-refereed


    • superconductors


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