T E M P U S P R O J E C T

Transcription

1 T E M P U S P R O J E C T GEOMAGNETIC MEASUREMENTS AND QUALITY STANDARDS No. IB_JEP GEOMAGNETIC AND ELECTROMAGNETIC MEASUREMENTS AND QUALITY STANDARDS Todor Delipetrov Jean Rasson Gerald Duma STIP, 2005

2 C O N T E N T S INTODUCTION TO GEOMAGNETISM THE GEOMAGNETIC FIELD OF THE EARTH Elements of geomagnetic field Geomagnetic maps GAUSS S METHOD OF ANALYSIS OF THE MAGNETIC FIELD VARIATIONS OF EARTH S MAGNETIC FIELD Time variations of the Earth s magnetic pole Variations of the magnetic pole over the geological evolution Secular variations Change of the Earth s magnetic moment Periodic variations Magnetic disturbances 60 INTRODUCION TO ELECTROMAGNETISM 63 Introduction to force and field MODEL OF MATTER Atoms and sub atomic particles Quantitisation of electricity Basic of electricity COULOMB S LAW AND SUPER POSITION OF ELECTRIC FORCES Coulomb s law Principle of super position of electric forces Experiment for electric force between three bodies Super position of electric force ELECTRIC FIELD AND STRENGTH OF VECTOR OF ELECTRIC FIELD Electric field Strength of vector of electric field Super position of electric field Equipotential lines of electric field vector GAUSS S LAW Flux of vector of electric field strength ELECTRIC FIELD POTENTIAL AND ELECTRIC VOLTAGE Idea of potential energy in electrostatic field 85

3 8.2. Electrostatic potential Difference of potentials Electric voltage Determination of potential from distribution of electric field Equipotential surfaces Determination of vector of strength of electric field from distribution of potential Electric dipole CONDUCTORS IN ELECTRIC FIELD Principle features of conductors Conditions for electrostatic balance The relation between electric field and distribution of electric charges on the surface of conductor Electrostatic induction Method of images Dependence of surface density of electric charge on image of the surface DIELECTRICS IN ELECTRIC FIELD Principle features of dielectrics Occurrence of polarization Kinds of polarization Vector of electric polarization MAGNETIC FIELD Magnetic force and magnetic occurrences Law of magnetic force between two current elements Force between two punctual charges MAGNETIC FIELD AND VECTOR OF MAGNETIC INDUCTION Vector of magnetic induction and Bio Savart law Vector lines of magnetic induction FORCE IN MAGNETIC FIELD Force and moment on current contour in magnetic field Moment of forces on ring of current in magnetic field Force and moment on non deformable contour in homogenous field AMPERE S LAW FLUX OF VECTOR OF MAGNETIC INDUCTION 152

4 15.1. Law for flux retention ELECTROMAGNETIC INDUCTION Induced electric field Idea for time variable magnetic field On movement Basic experiment for determination of electric and magnetic field Time variable electromagnetic field Faraday s law ELECTROMAGNETIC WAVES ALLOWED LEVELS OF ELECTROMAGNETIC RADIATION ACCORDING TO EU STANDARDS ANNEX I - Definitions Physical sizes Principle limitations and reference levels ANNEX II Principle limitations ANNEX III Reference levels Contact currents and boundary currents ANNEX IV Exposure from sources with multiple frequencies Principle limitations Reference levels MAGNETIC OBSERVATORY BASICS Building a magnetic observatory Site selection Territory of the magnetic observatory Instalattion of foundations and instrument pillars Non magnetic buildings Electric supply to the observing huts Astronomical azimuth mark/target Magnetic conditions in observatory environment Low magnetic field gradients Identical variation OBSERVATIONS WITH DIFLUX THEODOLITE The Diflux concept Angle units 205

5 21. OBSERVATIONS WITH THE PROTON MAGNETOMETER Measurement procedure with a proton magnetometer Check of a proton magnetometer electronics DETERMINATION OF PILLARS DF & INTERCOMPARISONS OF PROTON MAGNETOMETERS Introduction Description of the procedure Obtaining the equations Practical tips for accurate results Heading errors REDUCTION TO THE BASELINES OF A DFI, DHZ OR XYZ DIGITAL VARIOMETER WITH DIFLUX AND PROTON MAGNETOMETER ABSOLUTE OBSERVATIONS Introduction Case of DFI variometer General relationships Note on equations (19) and (20) Deriving Diflux instrumental errors Case of DHZ variometer Continuous proton magnetometer F record is available No continuous proton magnetometer F record is available Case of XYZ variometer Continuous proton magnetometer F record is available No continuous proton magnetometer F record is available Rotation of a XYZ variometer by software SPECIAL ISSUES IN REPEAT SURVEY MEASUREMENTS Astronomical sun obseravations for getting true north Procedure with the Zeiss Iena 010, 015 or 020 theodolite Processing of the astronomical observations Getting astronomical data from MICA The soleil.exe GWBASIC program Use of satellite imagery Extracting the image Rectifying the image 230

6 Transforming the image into a map Coverting topo maps coordinates to/from GPS obtained coordinates From one coordinate system to another: geodetic transformations Datums Topographic maps Global Navigation Satellite Systems (GNSS) Converting from a datum to another ANNEX I: PARAMETERS FOR DATUM CONVERSIONS BASICS OF NON IONIZING ELECTROMAGNETIC RADIATION AND MEASUREMENT PRACTICE Introduction Radiation Non ionizing radiation Frequency ranges by definition PART I: LOW FREQUENCY RANGE Physical units Magnetic field Electric field Natural electric and magnetic fields The most common technical fields Attenuation of intensity with distance Preventive limits set out by the WHO/IRRA for the general public Measurements Introduction Measure instruments for LF fields Measuring sites and objects Measuring protocol PART II: HIGH FREQUENCY RANGE Physical units The most common radio transmission fields Reference levels set out by the Council of EU (1999/519/??) Measurements Instruments Measuring sites and objects 268

7 Measuring protocol THE PUBLIC EXPOSURE TO ELECTRIC, MAGNETIC AND ELECTROMAGNETIC FIELDS, RESTRICTIONS AND STANDARDS, LITERATURE EXCERPTS Static magnetic fields Units Origins Results of studies Measurements (1994) Time varying electric, magnetic and electromagnetic fields Units Physics of sources Results of basic exposure studies Biological basic for limiting exposure (up to 100 KHz) Biological basic for limiting EMF exposure (100 khz-300 GHz) Guidelines for limiting EMF exposure 287

8 PREFACE This book, according to the authors opinion, contains the basic material for the candidates who will attend the courses organized within the Tempus Project under the title Geomagnetic Measurements and Quality Standards. It also gives other users the opportunity to study the theoretical grounds necessary in the application of up to date methodologies for measurements of electromagnetic and the magnetic field of the earth, data processing and their transformation into practical and useful indicators, comparable to normal values of the earth s magnetic field and allowed standards of electromagnetic radiation accept by European Union. Electromagnetic and geomagnetic investigations have seen intense development over the last decades, in terms of application of new technologies and in practical utilization of theoretical achievements. In the era of environmental protection, more and more projects deal with electromagnetic pollution caused by anthropological activities. The book is divided into three parts: geomagnetism, electromagnetism and standards for allowed electromagnetic radiation. The book will be used for training of personnel and better understanding of this specific scientific field in the Republic of Macedonia, thanks to the efforts of authors who were involved in the implementation of the Tempus Project Geomagnetic Measurements and Quality Standards financed by European Union.

9 Note This book is published in the Macedonian language (Cyrillic script). Therefore it is not available online.. Some parts of it are available in English on special request. For consultations, please contact author J. Rasson at or Telephone