Schmucker-Weidelt Lecture Notes, Aarhus, 1975 - MTNet
Schmucker-Weidelt Lecture Notes, Aarhus, 1975 - MTNet Schmucker-Weidelt Lecture Notes, Aarhus, 1975 - MTNet
the product WUL' constant with L denoting the length scale, The primary inducing field is produced by an oscilla-ting dipole source or-by extended current loops, situated as "ionospheric sources" above an arrangeme& of conductors which represent the conducting material below the Earth's surface. Alternatively, the conductors as a whole can be placed into the interior of coils, say Helmholtz coils, and thus be exposed to a uniform source field, .- \ I / I . 1 i: /' .
width, however, forces the induced currents to flow in loops which in strength and phase may be totally controlled by the edges of the conductor. In order to avoid this unwanted effect the source field at the level of the conductors should die away before reaching the edges of - the scale model. For instance, if a line current source is used, the half-width of the line current field on the surface of the scale model' should be considerably smaller then the width of the model.. These complicati.ons do not arise of course, when no attempt is made to simulate local anomal-ies of a large-scale induced current system, i.e. when the scale model is placed into the interior of coils in order to simulate local induction in isolated bodies (cf. subsection on this topLc in Sec. 9.4). Here are to men-tion the scale model experiments by GREWET and LAUNAY who showed how ,a large-scale induction can be simvlated also by the induction in the interior of coils. Their objective was to make a scale model of the coast effect at complicated coastlines. They nptedthat the i.nductive coupling between the ocean and highly conduc-ting ma-terial at some depth within the Earth is well represented by a system of image currents at the level 2 -hx below the ocean. Here h" is again the depth of a perfect substi-tute conductor for the oceanic substructure at the considered frequency. GRENCT and LAUNAY use as model conductors two thin metallic plates which are connected along two edges by vertical conducting strips.
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- Page 136 and 137: 9. --- Data 5.nterpretatj.on on the
- Page 138 and 139: The "modified apparent - - resistiv
- Page 140 and 141: Exercise Geomagne-tic varj.ations.
- Page 142 and 143: 9.2 Layered Sphere - The sphericity
- Page 144 and 145: The field within the conducting sph
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- Page 148 and 149: with I - and- a = gn g-n I 1 6-n-1
- Page 150 and 151: with ~ = - T E + as sheet current d
- Page 152 and 153: E~~ T r: j = const. or E T + E a r
- Page 154 and 155: Field equations and boundary condit
- Page 156 and 157: with N (w,y) being the Fourier tran
- Page 158 and 159: is calculated as function of freque
- Page 160 and 161: Both types of anomaly can be explai
- Page 162 and 163: A field line segment with the horiz
- Page 164 and 165: - 160 - below can neither enter nor
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- Page 172 and 173: anomalous conductivity oat OP the a
- Page 176 and 177: One of the thin plates represents t
- Page 178 and 179: low conductivity requires the use o
- Page 180 and 181: Other derivable properties of mantl
- Page 182: 11. References for general reading
width, however, forces the induced currents to flow in loops<br />
which in strength and phase may be totally controlled by the<br />
edges of the conductor. In order to avoid this unwanted effect<br />
the source field at the level of the conductors should die away<br />
before reaching the edges of - the scale model. For instance, if<br />
a line current source is used, the half-width of the line current<br />
field on the surface of the scale model' should be considerably<br />
smaller then the width of the model..<br />
These complicati.ons do not arise of course, when no attempt is<br />
made to simulate local anomal-ies of a large-scale induced current<br />
system, i.e. when the scale model is placed into the interior<br />
of coils in order to simulate local induction in isolated bodies<br />
(cf. subsection on this topLc in Sec. 9.4).<br />
Here are to men-tion the scale model experiments by GREWET and<br />
LAUNAY who showed how ,a large-scale induction can be simvlated<br />
also by the induction in the interior of coils. Their objective<br />
was to make a scale model of the coast effect at complicated<br />
coastlines. They nptedthat the i.nductive coupling between the<br />
ocean and highly conduc-ting ma-terial at some depth within the<br />
Earth is well represented by a system of image currents at the<br />
level 2 -hx below the ocean. Here h" is again the depth of a<br />
perfect substi-tute conductor for the oceanic substructure at the<br />
considered frequency.<br />
GRENCT and LAUNAY use as model conductors two thin metallic plates<br />
which are connected along two edges by vertical conducting strips.
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