Bipolar programmable current supply for superconducting nuclear magnetic resonance magnets
作者:
Jaakko Koivuniemi,
Reeta Luusalo,
Pertti Hakonen,
期刊:
Review of Scientific Instruments
(AIP Available online 1998)
卷期:
Volume 69,
issue 9
页码: 3418-3425
ISSN:0034-6748
年代: 1998
DOI:10.1063/1.1149109
出版商: AIP
数据来源: AIP
摘要:
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±10 A,the sweep rate can be set between 1 &mgr;A/s–140 mA/s, and the maximum output voltage is±2.5 V.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. ©1998 American Institute of Physics.
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