On Oct 26, 3:43 pm, Jamie
solar flares cause massive disturbances to the earth's magnetic field.
Take a look at the Noise Floor of the Earth's Field:
<
http://www.vlf.it/naturalnoisefloor/naturalnoisefloor.htm>
the field noise data cmoes ffrom actual meaurments of sites
From paper, here is its bibliography:
1. E.L. Maxwell and D.L. Stone, "Natural Noise Fields 1cps to 100kc",
IEEE Transactions on Antennas an Propagation, Volume AP-11, Number 3,
pp 339-43, May 1963.
2_ D.A. Chrissan, A.C. Fraser-Smith, Seasonal Variations of Globally
Measured ELF/VLF Radio Noise, Technical Report D177-1, Stanford
University Dept of Electrical Engineering, STAR Lab, December 1996.
3_ R. Barr, D. Llanwyn Jones, C.J. Rodger, "ELF and VLF radio waves",
Journal of Atmospheric and Solar-Terrestrial Physics, Volume 62, Issue
18, pp 1689-1718, November 2000.
4_ Kenneth Davies, Chapter 9, Propagation of Low and Very Low
Frequency Waves, Ionospheric Radio Propagation, New York, N.Y., Dover
Publications, Inc., 1966.
5_ M. Balser and C.A. Wagner, "Observations of Earth-ionosphere cavity
resonances", Nature, Volume 188, pp 638-41, 1960
Magnetic fields are insidious, once created you can't destroy them,
simply redirect them. And, low frequency are the worst, because they
penetrate EVERYTHING! Using mumetal can get expensive, and if not done
properly can easily exacerbate the problem by 'sucking' in magnetic
fields and actually intensifying them locally, so even that type of
shielding must be done carefully.
from those charts:
at 1 Hz the noise spectral density is 'normally' 1pT/rtHz, and it has
a 1/f distribution [I think]
at 0.01Hz it has climbed to over 1nT/rtHz.
If your e-beams are low speed, circa 10-20kV and the run path is long,
it doesn't take much field to deflect the beam over 100nm down at the
target, which in today's geometries is HUGE!
Has anybody produced the calculations for you? It should be part of
your equipment's performance spec - specifying the operating ambient
fields that are allowed. Then it'sup to you to prove your fields are
less than that.
Anyway, the number in those charts is 'average' which means during
solar storms it can easily go above 10X that value - for days! and
even into the 100X for short periods.
Do you have ambient magnetic field instrumentation monitoring the
fields? They are purchaseable items.