deperm

Etymology

de- (“prefix indicating removal or reversal”) + perm(anent magnet).

verb

1. (transitive, chiefly nautical) To degauss or demagnetize; especially, to degauss a ship by dragging a large powered electrical cable along its side.
   Vessels wiped and depermed as outlined above were found to age towards their original state, so the processes as described were only effective for comparatively short periods and had to be repeated at regular intervals. 1948, The School Science Review: A Magazine for Science Teachers, volume 30, London: John Murray for the Science Masters' Association and the Association of Women Science Teachers, →ISSN, →OCLC, page 46
   Our present system deperms more reliably and is arranged to deperm the sensor each time the power source for the magnetometer is turned on. 1964 June, Manual for Fluxgate Ferrite Magnetometer (CRSR; 172), Ithaca, N.Y.: Center for Radiophysics and Space Research, Cornell University, →OCLC, page 6
   When it is not possible to deperm the assembly below 95% of the post exposure magnitude, ascertain if the component contains parts with permanent magnets such as relays which would not deperm in the 50 gauss field. 1966 April, C[hester] L. Parsons, C. A. Harris, “Appendix C: Test Procedure”, in IMP-I Spacecraft Magnetic Test Program (NASA Technical Note; D-3376), Washington, D.C.: National Aeronautics and Space Administration, →OCLC, archived from the original on 2017-03-12, page 33
   Deperming the boards individually lead to a significant decrease in the magnetic moment of the whole unit, this was then repeated on all units. 2008, M. Ludlam et al., “The THEMIS Magnetic Cleanliness Program”, in J[ames] L. Burch, V[assilis] Angelopoulos, editors, The THEMIS Mission:[…], [New York, N.Y.]: Springer Science+Business Media, published 2009, →DOI, section 4 (Unit Testing), page 176

noun

1. (chiefly nautical) The act or process of deperming.
   Fortunately a very pronounced extension of life was found to be possible for wipes and deperms by making the initial current very strong so that, for example, a positive component was made a larger negative one before being reduced to zero […] 1948, The School Science Review: A Magazine for Science Teachers, volume 30, London: John Murray for the Science Masters' Association and the Association of Women Science Teachers, →ISSN, →OCLC, page 46
   One interesting feature of the S/N 008A and S/N 009 data is that the residual moment after deperms one through three increased from 735 to 870 pole-cm for S/N 008A, but decreased from 854 to 659 pole-cm for S/N 009. 23 December 1968, A. W. Fihelly, “Appendix III: Memorandum by A. W. Fihelly re SNAP-19 S/N 009 Magnetic Moments Measurement”, in W[illia]m S. West, J. Michael Holman, Herbert W. Bilsky, Techniques for Achieving Magnetic Cleanliness on Deep-space Missions: A Report Covering Task III Effort under the Study: NASA Evaluation with Models of Optimized Nuclear Spacecraft (NEW MOONS), Greenbelt, Md.: Goddard Space Flight Center, published April 1969, →OCLC, archived from the original on 2017-03-03, pages III-3–III-4