1. The Van Allen belt – A radiation belt is a zone of energetic charged particles, most of which originate from the solar wind that is captured by and held around a planet by that planets magnetic field. The Earth has two belts and sometimes others may be temporarily created. The discovery of the belts is credited to James Van Allen, Earths two main belts extend from an altitude of about 1,000 to 60,000 kilometers above the surface in which region radiation levels vary. Most of the particles form the belts are thought to come from solar wind. By trapping the solar wind, the magnetic field deflects those energetic particles, the belts are located in the inner region of the Earths magnetosphere. The belts trap energetic electrons and protons, other nuclei, such as alpha particles, are less prevalent. The belts endanger satellites, which must have their sensitive components protected with adequate shielding if they spend significant time in that zone, kristian Birkeland, Carl Størmer, and Nicholas Christofilos had investigated the possibility of trapped charged particles before the Space Age. Explorer 1 and Explorer 3 confirmed the existence of the belt in early 1958 under James Van Allen at the University of Iowa, the trapped radiation was first mapped by Explorer 4, Pioneer 3 and Luna 1. The term Van Allen belts refers specifically to the radiation belts surrounding Earth, however, the Sun does not support long-term radiation belts, as it lacks a stable, global, dipole field. The Earths atmosphere limits the belts particles to regions above 200–1,000 km, the belts are confined to a volume which extends about 65° on either side of the celestial equator. The NASA Van Allen Probes mission aims at understanding how populations of relativistic electrons and ions in space form or change in response to changes in solar activity, the Van Allen Probes mission successfully launched on August 30,2012. The primary mission is scheduled to last two years with expendables expected to last four, NASAs Goddard Space Flight Center manages the Living With a Star program of which the Van Allen Probes is a project, along with Solar Dynamics Observatory. The Applied Physics Laboratory is responsible for the implementation and instrument management for the Van Allen Probes, Radiation belts exist around other planets and moons in the solar system that have magnetic fields powerful enough to sustain them. To date, most of these belts have been poorly mapped. The Voyager Program only nominally confirmed the existence of similar belts around Uranus, the inner Van Allen Belt extends typically from an altitude of 0.2 to 2 Earth radii or 1,000 km to 6,000 km above the Earth. In certain cases when solar activity is stronger or in areas such as the South Atlantic Anomaly. The inner belt contains high concentrations of electrons in the range of hundreds of keV and energetic protons with energies exceeding 100 MeV, the source of lower energy protons is believed to be proton diffusion due to changes in the magnetic field during geomagnetic storms. Due to the offset of the belts from Earths geometric centerThe Van Allen belt – Jupiter's variable radiation belts
2. Conduction current – An electric current is a flow of electric charge. In electric circuits this charge is carried by moving electrons in a wire. It can also be carried by ions in an electrolyte, or by both ions and electrons such as in an ionised gas. The SI unit for measuring a current is the ampere. Electric current is measured using a device called an ammeter, electric currents cause Joule heating, which creates light in incandescent light bulbs. They also create magnetic fields, which are used in motors, inductors and generators, the particles that carry the charge in an electric current are called charge carriers. In metals, one or more electrons from each atom are loosely bound to the atom and these conduction electrons are the charge carriers in metal conductors. The conventional symbol for current is I, which originates from the French phrase intensité de courant, current intensity is often referred to simply as current. The I symbol was used by André-Marie Ampère, after whom the unit of current is named, in formulating the eponymous Ampères force law. The notation travelled from France to Great Britain, where it became standard, in a conductive material, the moving charged particles which constitute the electric current are called charge carriers. In other materials, notably the semiconductors, the carriers can be positive or negative. Positive and negative charge carriers may even be present at the same time, a flow of positive charges gives the same electric current, and has the same effect in a circuit, as an equal flow of negative charges in the opposite direction. Since current can be the flow of positive or negative charges. The direction of current is arbitrarily defined as the same direction as positive charges flow. This is called the direction of current I. If the current flows in the direction, the variable I has a negative value. When analyzing electrical circuits, the direction of current through a specific circuit element is usually unknown. Consequently, the directions of currents are often assigned arbitrarilyConduction current – A simple electric circuit, where current is represented by the letter i. The relationship between the voltage (V), resistance (R), and current (I) is V=IR; this is known as Ohm's Law.
3. Adiabatic ionization – Ionization is the process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons to form ions, often in conjunction with other chemical changes. Ionization can result from the loss of an electron after collisions with particles, collisions with other atoms, molecules and ions. Heterolytic bond cleavage and heterolytic substitution reactions can result in the formation of ion pairs, ionization can occur through radioactive decay by the internal conversion process, in which an excited nucleus transfers its energy to one of the inner-shell electrons causing it to be ejected. Everyday examples of gas ionization are such as within a fluorescent lamp or other electrical discharge lamps and it is also used in radiation detectors such as the Geiger-Müller counter or the ionization chamber. The ionization process is used in a variety of equipment in fundamental science and in such as mass spectrometry. Negatively charged ions are produced when an electron collides with an atom and is subsequently trapped inside the electric potential barrier. The process is known as electron capture ionization, positively charged ions are produced by transferring a sufficient amount of energy to a bound electron in a collision with charged particles or with photons. The threshold amount of the energy is known as ionization potential. The study of such collisions is of importance with regard to the few-body problem. The Townsend discharge is an example of the creation of positive ions. It is a reaction involving electrons in a region with a sufficiently high electric field in a gaseous medium that can be ionized. Following an original event, due to such as ionizing radiation. If the electric field is strong enough, the free electron gains sufficient energy to liberate a further electron when it collides with another molecule. The two free electrons then travel towards the anode and gain sufficient energy from the field to cause impact ionization when the next collisions occur. This is effectively a chain reaction of electron generation, and is dependent on the free electrons gaining sufficient energy between collisions to sustain the avalanche, ionization efficiency is the ratio of the number of ions formed to the number of electrons or photons used. The trend in the energy of atoms is often used to demonstrate the periodic behavior of atoms with respect to the atomic number. This is a tool for establishing and understanding the ordering of electrons in atomic orbitals without going into the details of wave functions or the ionization process. An example is presented in figure 1, the periodic abrupt decrease in ionization potential after rare gas atoms, for instance, indicates the emergence of a new shell in alkali metalsAdiabatic ionization – Figure 1. Ionization energies of neutral elements.
4. Electrosphere – The ionosphere is a region of Earths upper atmosphere, from about 60 km to 1,000 km altitude, and includes the thermosphere and parts of the mesosphere and exosphere. It is ionized by radiation, plays an important part in atmospheric electricity. It has practical importance because, among other functions, it influences radio propagation to distant places on the Earth. The ionosphere is a shell of electrons and electrically charged atoms and molecules that surrounds the Earth and it owes its existence primarily to ultraviolet radiation from the Sun. The lowest part of the Earths atmosphere, the troposphere extends from the surface to about 10 km, above 10 km is the stratosphere, followed by the mesosphere. In the stratosphere incoming solar radiation creates the ozone layer, at heights of above 80 km, in the thermosphere, the atmosphere is so thin that free electrons can exist for short periods of time before they are captured by a nearby positive ion. The number of free electrons is sufficient to affect radio propagation. This portion of the atmosphere is ionized and contains a plasma which is referred to as the ionosphere, in this process the light electron obtains a high velocity so that the temperature of the created electronic gas is much higher than the one of ions and neutrals. The reverse process to ionization is recombination, in which an electron is captured by a positive ion. Recombination occurs spontaneously, and causes the emission of a photon carrying away the energy produced upon recombination, as gas density increases at lower altitudes, the recombination process prevails, since the gas molecules and ions are closer together. The balance between two processes determines the quantity of ionization present. Ionization depends primarily on the Sun and its activity, the amount of ionization in the ionosphere varies greatly with the amount of radiation received from the Sun. Thus there is an effect and a seasonal effect. The local winter hemisphere is tipped away from the Sun, thus there is less received solar radiation, the activity of the Sun is associated with the sunspot cycle, with more radiation occurring with more sunspots. Radiation received also varies with geographical location, there are also mechanisms that disturb the ionosphere and decrease the ionization. There are disturbances such as flares and the associated release of charged particles into the solar wind which reaches the Earth. At night the F layer is the layer of significant ionization present. During the day, the D and E layers become more heavily ionized, as does the F layerElectrosphere – Electric currents created in sunward ionosphere.
5. Hydromagnetics – Magnetohydrodynamics is the study of the magnetic properties of electrically conducting fluids. Examples of such magnetofluids include plasmas, liquid metals, salt water, the word magnetohydrodynamics is derived from magneto- meaning magnetic field, hydro- meaning water, and -dynamics meaning movement. The field of MHD was initiated by Hannes Alfvén, for which he received the Nobel Prize in Physics in 1970. The fundamental concept behind MHD is that magnetic fields can induce currents in a conductive fluid. The set of equations that describe MHD are a combination of the Navier-Stokes equations of fluid dynamics and these differential equations must be solved simultaneously, either analytically or numerically. The importance of the waves in this respect are pointed out. The ebbing salty water flowing past Londons Waterloo Bridge interacts with the Earths magnetic field to produce a difference between the two river-banks. Michael Faraday tried this experiment in 1832 but the current was too small to measure with the equipment at the time, however, by a similar process the voltage induced by the tide in the English Channel was measured in 1851. The simplest form of MHD, Ideal MHD, assumes that the fluid has so little resistivity that it can be treated as a perfect conductor and this is the limit of infinite magnetic Reynolds number. In ideal MHD, Lenzs law dictates that the fluid is in a sense tied to the field lines. To explain, in ideal MHD a small volume of fluid surrounding a field line will continue to lie along a magnetic field line. This is sometimes referred to as the field lines being frozen in the fluid. This difficulty in reconnecting magnetic field makes it possible to store energy by moving the fluid or the source of the magnetic field. The energy can become available if the conditions for ideal MHD break down. The ideal MHD equations consist of the continuity equation, the Cauchy momentum equation, Amperes Law neglecting displacement current, as with any fluid description to a kinetic system, a closure approximation must be applied to highest moment of the particle distribution equation. This is often accomplished with approximations to the flux through a condition of adiabaticity or isothermality. The main quantities which characterize the electrically conducting fluid are the plasma velocity field v, the current density J, the mass density ρ. The flowing electric charge in the plasma is the source of a magnetic field B, All quantities generally vary with time tHydromagnetics – The sun is an MHD system that is not well understood.
6. Planetary magnetic field – A magnetosphere is the region of space surrounding an astronomical object in which charged particles are controlled by that objects magnetic field. The magnetic field near the surface of many astronomical objects resembles that of a dipole, the field lines farther away from the surface can be significantly distorted by the flow of electrically conducting plasma emitted from a nearby star. Study of Earths magnetosphere began in 1600, when William Gilbert discovered that the field on the surface of Earth resembled that on a terrella. In the 1940s, Walter M. Elsasser proposed the model of dynamo theory, through the use of magnetometers, scientists were able to study the variations in Earths magnetic field as functions of both time and latitude and longitude. Beginning in the late 1940s, rockets were used to study cosmic rays, in 1958, Explorer 1, the first of the Explorer series of space missions, was launched to study the intensity of cosmic rays above the atmosphere and measure the fluctuations in this activity. This mission observed the existence of the Van Allen radiation belt, also in 1958, Eugene Parker proposed the idea of the solar wind. The term magnetosphere was proposed by Thomas Gold in 1959, the Explorer 12 mission led to the observation by Cahill and Amazeen in 1963 of a sudden decrease in the strength of the magnetic field near the noon meridian, later named the magnetopause. In 1983, the International Cometary Explorer observed the magnetotail, or the distant magnetic field, the distance at which a planet can withstand the solar wind pressure is called the Chapman–Ferraro distance. Mercury, Earth, Jupiter, Ganymede, Saturn, Uranus, a magnetosphere is classified as induced when R C F ≪ R P, or when the solar wind is not opposed by the objects magnetic field. In this case, the solar wind interacts with the atmosphere or ionosphere of the planet, when R C F ≈ R P, the planet itself and its magnetic field both contribute. It is possible that Mars is of this type, the bow shock forms the outermost layer of the magnetosphere, the boundary between the magnetosphere and the ambient medium. For stars, this is usually the boundary between the wind and interstellar medium, for planets, the speed of the solar wind there decreases as it approaches the magnetopause. The magnetosheath is the region of the magnetosphere between the bow shock and the magnetopause and it is formed mainly from shocked solar wind, though it contains a small amount of plasma from the magnetosphere. It is an area exhibiting high particle flux, where the direction. This is caused by the collection of solar wind gas that has effectively undergone thermalization and it acts as a cushion that transmits the pressure from the flow of the solar wind and the barrier of the magnetic field from the object. The magnetopause is the area of the magnetosphere wherein the pressure from the magnetic field is balanced with the pressure from the solar wind. It is the convergence of the solar wind from the magnetosheath with the magnetic field of the object. Because both sides of this convergence contain magnetized plasma, the interactions between them are complex, the structure of the magnetopause depends upon the Mach number and beta of the plasma, as well as the magnetic fieldPlanetary magnetic field – Infrared image and artist's concept of the bow shock around R Hydrae