Magnetic Susceptibility Meter

[JC1]

Same ol problem

Working under NASA's principle of "Follow the Water" the objectives of this investigation are to measure the electromagnetic properties of Mars analog materials under Mars ambient conditions.

Static magnetic experiments performed by Viking, Pathfinder, Spirit and Opportunity determined that magnetic minerals exist in Martian sediments. The presence of these magnetic minerals could make finding water on Mars using electromagnetic methods complicated. The frequency and temperature dependent properties of the Martian magnetic minerals, as well as their impact on electromagnetic measurements are unknown.

Experience in places like Australia and Hawaii with high iron oxide content ("red") soils has shown that magnetic minerals can strongly impact electromagnetic geophysical exploration.

Strongly Impact

School of Mines Ryan?

Excellent !!!

http://mars.mines.edu/index.htm

Magnetic Sup on Mars !!!

Now I see what you two are up to !

You guys are planning to Mine Mars !!!!


Most of the Martian analog samples in this investigation have been measured using a Bartington Instruments magnetic susceptibility meter that measures at 465 Hz and 4,650 Hz.

http://mars.mines.edu/magsus/Bart/index.htm

A new conspiracy theory.

too much fun.

[gem2neophyte]

magnetic susceptibility and electrical conductivity

hello to all,

can somebody please explain in laymans term, the difference between magnetic susceptibility and electrical conductivity in geophysics? Assuming i am scanning an area for 2 burried 2feet diameter drums, assuming that an instrument i used acquired this two data (for mag.susc and elec.cond) and displayed it on 2d, what will be my basis for the drums signature, is it mag.susc or elect. conductivity display?

thank you

[99thpercentile]

Magnetic susceptibility is the ratio of the magnetization of a material to the applied field. It is the physical property that affects a magnetometer survey. The earth's magnetic field is the applied field and the magnetic susceptibility of the soil controls the magnetization of the material. When mapping the ground with a magnetometer you generate a map of apparent magnetic susceptibility.

Electrical conductivity, or its reciprocal electrical resistivity, refers to the ease of movement of charges through a medium. This is the physical property of most interest to metal detectors.

Magnetic viscosity, the subject of this series of posts, is really an electromagnetic phenomenon not a magnetic phenomenon. Electromagnetic surveys are active surveys as opposed to magnetic surveys being passive. By active I mean that the user is generating the source signal. If the ground has zero magnetic viscosity then the electromagnetic energy generated by the transmitter travels into the ground and interacts with the soil. The soil generates a secondary magnetic field which is recorded by the receiver. The secondary magnetic field is a function of the magnetic susceptibility and the electrical conductivity. The response at the receiver is almost instantaneous. If the soil exhibits magnetic viscosity, there is a delay in the response recorded by the receiver. This can cause the response of the soil and a buried target to be almost indistinguishable.

From your description it sounds like you are looking for two buried 55 gallon drums. I am not sure, but it seems as if you are using a metal detector. If this is true the electrical conductivity would be the most important. But there is a caveat that it depends if you are using a time domain or frequency domain instrument and what information you are using from the data. Are you using a geophysical instrument that records the data? There are several other questions that I could ask that would help me give you useful guidance.

What type of sensor are you using?
Is it time domain or frequency domain?
Are you recording the data?
How are you plotting the data?
Are you doing any data processing?

[gem2neophyte]

mag sus and elec cond

thank you for your time,

the em is gem2 by geophex, and yes it has data and downloadable, using wingem and to the surfer 8....it is correct, i am looking for a 2 55 gal buried drums at 30 feet aprox,,,,,why is it that it is only in mag.susc that the drums appeared, and not in electrical conductivity? since ferrous drums are also conductive, it should be seen also right?.....another question...what are we seeing at electrical conductivity test if the drums did not appear? does electrical conductivity test output is not useful for cache hunting?

thanks again

gem2neophyte

Magnetic susceptibility is the ratio of the magnetization of a material to the applied field. It is the physical property that affects a magnetometer survey. The earth's magnetic field is the applied field and the magnetic susceptibility of the soil controls the magnetization of the material. When mapping the ground with a magnetometer you generate a map of apparent magnetic susceptibility.

Electrical conductivity, or its reciprocal electrical resistivity, refers to the ease of movement of charges through a medium. This is the physical property of most interest to metal detectors.

Magnetic viscosity, the subject of this series of posts, is really an electromagnetic phenomenon not a magnetic phenomenon. Electromagnetic surveys are active surveys as opposed to magnetic surveys being passive. By active I mean that the user is generating the source signal. If the ground has zero magnetic viscosity then the electromagnetic energy generated by the transmitter travels into the ground and interacts with the soil. The soil generates a secondary magnetic field which is recorded by the receiver. The secondary magnetic field is a function of the magnetic susceptibility and the electrical conductivity. The response at the receiver is almost instantaneous. If the soil exhibits magnetic viscosity, there is a delay in the response recorded by the receiver. This can cause the response of the soil and a buried target to be almost indistinguishable.

From your description it sounds like you are looking for two buried 55 gallon drums. I am not sure, but it seems as if you are using a metal detector. If this is true the electrical conductivity would be the most important. But there is a caveat that it depends if you are using a time domain or frequency domain instrument and what information you are using from the data. Are you using a geophysical instrument that records the data? There are several other questions that I could ask that would help me give you useful guidance.

What type of sensor are you using?
Is it time domain or frequency domain?
Are you recording the data?
How are you plotting the data?
Are you doing any data processing?

[Unregistered]

sir

any reply sir?..........

[JC1]

I'll do One

I'll do a reply.

Maybe will help.

Not an expert on this one.

Never stopped me yet.

One of the disadvantages of an electromagnetic induction (EMI) instrument, such as an EM 31 or a GEM 2, is that it is unable to penetrate a layer of high conductivity. In short, the EM radiation emitted from an EMI sensor will only penetrate down to the layer of high conductivity Therefore, while it will give a very accurate estimate of the horizontal extent of the impact in two dimensions, it will not address the vertical dimension that is necessary for information about the plume volume or dispersion. In order to gain information about the plume of conductivity, intrusive measurements must be conducted.

http://www.penserv.ab.ca/nextstep.htm

Magnetic Methods

Basic Concept: A metal tank is magnetized by the Earth's magnetic field. It then produces a secondary field. The resultant field contains both the Earth's magnetic field and the field from the tank and results in a distortion of the Earth's magnetic field. A magnetometer can be used to survey an area where metal tanks are expected and should be able to locate the tanks.

http://www.cflhd.gov/agm/engApplicat...orageTanks.htm

[JC1]

links

Gravity measurements !!!

http://www.umr.edu/2006geophysics/hg...0landfills.pdf

The U.S. Geological Survey has conducted a study of the use of the Geophex GEM-2 handheld broadband electromagnetic induction system to provide resistivity depth sections. The GEM-2 allows the collection of multiple frequency data with a fixed offset single receiver/transmitter coil set in an easily portable system that allows global positioning system input. The system produces data similar to airborne frequency domain electromagnetic systems with streaming data at multiple frequencies along a line. In order to invert the data, care needed to be exercised in the analysis of noise selection of frequencies, drift leveling, and calibration. Due to the nature of the broadband instrument smoothing of the data was necessary as noise levels are substantially greater than tuned loop systems. Dc resistivity data were collected at a fixed calibration point to be used to adjust the response, and for accurate drift leveling. These steps have produced useful resistivity depth images that compare to dc resistivity images at selected field sites. The resistivity depth images produced by a broadband EM induction system can provide a useful view of the subsurface allowing more accurate determinations of targets, more cost effective placement of subsurface sampling/drilling, and more accurate volume calculations.

http://www.x-cd.com/sageep06cd/prof53.html

[wyndham]

My apologies to all because I am once again treading in a swamp of ignorace on my part.
But,is it possible that the magnetic lag is due to the coupling of the iron and the silica causing a responce that , for want of the proper term, a feedback in the iron silicate where the crystal of silica is producing energy because of the induced pulse and there fore the viscosity.
I am a potter and the interaction of iron and silica in my glazes and the cooling at different points causes different types of iron crystal to form with in the glaze matrix. I use this behavior to produce different optical effect.
My point I guess is the reaction of a material not possibly concidered as important, may well play a bigger part. Maybe the frequency is based,in part,on the silica.
Wyndham

[99thpercentile]

Most theory says that magnetic viscosity is due primarily to grain size, although there is some debate over the actual cause. The issue is how quickly magnetic domains can rotate from the orientation that the external field places them in back to the orientation that they were in in the absence of the external field. Larger grain materials have multiple domains and it is impossible to get all of the magnetic domains to orient in the same direction when dealing with high frequencies. Small grain materials can be superparamagnetic, which means that each grain may have only one magnetic domain. This domain is not influence by other domains in the same grain and can rotate further in a fixed amount of time than a multidomain grain. At higher frequencies only the superparamagnetic grains can rotate back, while the larger grains cannot leading to smaller susceptibility values.

Dearing, J., 1994, Environmental magnetic susceptibility using the Bartington MS2 system, Chi Publishing,

[gem2neophyte]

gem2 data

I'll do a reply.

Maybe will help.

Not an expert on this one.

Never stopped me yet.

One of the disadvantages of an electromagnetic induction (EMI) instrument, such as an EM 31 or a GEM 2, is that it is unable to penetrate a layer of high conductivity. In short, the EM radiation emitted from an EMI sensor will only penetrate down to the layer of high conductivity Therefore, while it will give a very accurate estimate of the horizontal extent of the impact in two dimensions, it will not address the vertical dimension that is necessary for information about the plume volume or dispersion. In order to gain information about the plume of conductivity, intrusive measurements must be conducted.

http://www.penserv.ab.ca/nextstep.htm

Magnetic Methods

Basic Concept: A metal tank is magnetized by the Earth's magnetic field. It then produces a secondary field. The resultant field contains both the Earth's magnetic field and the field from the tank and results in a distortion of the Earth's magnetic field. A magnetometer can be used to survey an area where metal tanks are expected and should be able to locate the tanks.

http://www.cflhd.gov/agm/engApplicat...orageTanks.htm

i thank you sir for that reply, clear enough in layman's term......yes, to determine the most accurate depth, we have to use another method, say multiple probe earth resistivity meter with imagging (vertical display), taking note on inverse polarization,.....so the drawback of gem2 were taken care of when it comes to soil electrical conductivity.....one more thing...i beleive gem2 has a built-in magnetometer(cesium), isnt it right sir? for the magnetic susceptibility? does a magnetometer depth of penetration depends also in some factors like soil,rocks?pardon my ignorance...

thanks for the link on federal lands highway program.....that is definitely informative for a cache hunter like me...

truly yours,
gem2neophyte

[JC1]

Patent?

Forgot about patents

still looks a bit involved.

METHOD FOR MEASURING MAGNETIC SUSCEPTIBILITIES

http://www.google.com/patents?id=Kg1...eter+schematic

http://www.google.com/patents?id=RRM...eter+schematic


Abstract

An important methodological question for magnetic susceptibility measurements is if a variation of the soil conductivity, as a result of a change in soil moisture, influences the measured susceptibility values. An answer to this question is essential because an accurate magnetic susceptibility mapping requires a grid of comparable magnetic susceptibility values, which indicate the magnetic iron-mineral contents of the soils. Therefore, in the framework of the MAGPROX project (EU-Project EVK2-CT-1999-00019), the study aims at investigating the influence of soil moisture and the possible correlation between magnetic susceptibility and electric conductivity. This approach was realised by model experiments in the laboratory and a field monitoring experiment, which was performed in an analogical manner as the model. For the laboratory experiment, a plastic tub with a water in- and outflow system and installed lines of electrodes was used. The measurements were carried out with layers of different magnetic material within the experimental sand formation under varying water saturation conditions. For the field experiment, which was carried out from July to December 2003, two test sites were selected. The magnetic susceptibility was measured by means of the recently developed vertical soil profile kappa meter SM400 and a commonly used Bartington MS2D probe. The electric resistivity was recorded using a 4-point light system (laboratory) and a ground conductivity meter EM38 (field). The knowledge of the resistivity of the sand formation enabled an estimation of porosity and water saturation in consideration of the Archie equations. The laboratory experiment results showed a very slight variation of measured magnetic susceptibility under different degrees of moisture, indicating mainly the influence from the diamagnetic contribution of the water volume. A measurement error in connection with the measurement method, for example caused by an interfering effect of soil conductivity variations, was not found. The authors conclude, that in practical use of the investigated instruments for topsoil magnetic susceptibility mapping in the field, the influence of soil moisture and resulting soil conductivity can be neglected, especially compared to the influence of the contact between measurement loop and soil. The study presented here verifies the magnetic susceptibility data reproducibility and comparability, which provides the basis for magnetic susceptibility monitoring. Additionally, new application approaches of magnetic susceptibility measurements were proposed, which show again the versatility and the potential of the method.

http://www.sciencedirect.com/science...8d5da5efb5cc16

[Wirechief]

Hi Eric, I hope all is well with ya and I am enjoying the discussion here on this thread. Also I want to say hello to Wyndham! I am to be included in the ignorance dept.

I am curious if the medium between the loop and ground surface has any effect on the eddy currents from say a gold nugget? Or is this just nitpicking?

Eric I am wishing you all the best in your quest for conquering that nasty ground in Australia. Ok I just am being curious and thank you all for sharing the knowledge. God Bless.

John Tomlinson,CET
John's Detectors
Blackwell,Tx.
Land of the Mighty Diamondback!

[tjfinan]

MS Field Meter

I would be very interested in hearing about any developments of MS meters that can be used for field survey. The Bartington is typically used for archaeological surveying (my interest), but it is really cost prohibitive. At the same time SM-30 would be ideal, but I cant imagine bending over 400 times to survey a 20m x 20m grid square!

Any thoughts or ideas appreciated.

Tom

[Alpegee]

Susceptibility, is a specific electronic device to make a measurements, in this blog, find a mixed physical technologies, please I am do not understanding, is only ideas storm,?

Please explain me, Tanks in advance,,,