The interaction of optical maser plasma with regard to a surface is reported in the procedure of optical maser plasma interaction.The dynamic account of the plasma was visualized by utilizing CCD picture camera. Before we discuss about optical maser plasma interaction we must be familiar with the term optical maser so foremost we will discourse optical maser.
LASER AND LASER LIGHT-
Laser is an acronym for Light Amplification by Stimulated Emission of Radiation. It is a particular type of emanation that involves either atoms or molecules.Since the find of optical maser in 1960 it has been used in legion system designed to run in the gas, liquid and solid province. These systems emit radiation s with wavelength runing from infrared seeable and UV. The coming of optical maser was genuinely revolutionized scientific discipline medical specialty and engineering.
Laser is a procedure by which we can acquire a visible radiation beam which is consistent, extremely monochromatic or it has exactly known wavelength, and therefore energy, and about absolutely parallel or really much intense. The word optical maser is besides used for the visible radiation obtained by this procedure. All the photons in the light beam, emitted by different atoms at different blink of an eyes are in stage. The spread alteration in wavelength is really little, it is of the order of 106 nanometers, which is about 103 times smaller than the spread in the usual Kr visible radiation.
A beam of optical maser can travel to the Moon and return to the Earth without much loss in the strength. This shows that optical maser may be obtained as an about absolutely parallel beam.
To understand the procedure involved in optical maser, we have to first discuss stimulated emanation.
STIMULATED EMISSION –
Let us see an atom which is in the higher energy province E2.If we merely leave the atom at that place, it will finally holding energy E2-E1.This procedure is called self-generated emanation. Typically an atom stays for 10ns in an exited province. The mean clip for which an atom stays in an exited province is called the life-time of that province. There are atoms which are holding certain exited province holding a life-time of the order of a msec. That is approximately 105 times longer than the usual life-time. Such provinces are called metastable provinces.
Finally say the atom is in the higher energy province E2 and a photon holding energy E2-E1 is incident on it. The incident photon interacts with the atom and may do the atom to come down to the lower energy province. A fresh photon is emitted in the procedure. This procedure is different from self-generated emanation in which the atom jumps to the lower energy on its ain. In the present instance the incident photon has stimulated the atom to do the leap.
When an atom emits a photon due to its interaction with a photon incident on it, the procedure is called stirred emanation. The emitted photon has precisely the same energy, stage and way as the incident photon.
PROPERTIES OF LASER-
( I ) LASER LIGHT IS HIGHLY MONOCHROMATIC-
Laser from an ordinary incandescent monochromatic. The radiation from a fluorescent Ne mark is monochromatic, true, to about 1 portion in 106, but the acuteness of definition of optical maser visible radiation can be many times greater, every bit much as 1 portion in 1015.
( II ) THE LASER LIGHT IS HIGHLY COHERENT-
Individual long waves for optical maser visible radiation can be several hundred kilometre long. When two separated beams that have traveled such distance over separate waies are recombined, they remember their common beginning and are able signifier a form of intervention peripheries. The corresponding coherency length for moving ridge trains emitted by a light bulb is typically less than a metre.
( III ) LASER LIGHT IS HIGHLY DIRECTIONAL –
A optical maser beam spreads really small ; it departs from rigorous correspondence merely because of diffraction at the issue aperture of the optical maser. For illustration, a optical maser pulsation used to mensurate the distance to the Moon generates a topographic point on the Moon ‘s surface with a diameter of merely a few metres. Light from an ordinary bulb can be made into an about parallel beam by a lens, but a beam divergency is much greater than for a leser visible radiation. Each point from a light bulbs fibril forms its ain separate beam, and the angular divergency of the overall composite beam is set by the size of the fibril.
( IV ) LASER LIGHT CAN BE SHARPLY FOCUSED –
If two light beams transport the same sum of energy, the beam can be focused to the smaller topographic point will hold the greater strength at that topographic point. For optical maser visible radiation, the focussed topographic point can be so little that the strength at that topographic point. For optical maser visible radiation, the focussed topographic point can be so little that the strength of 1017 W/cm2 is readily obtained. An oxyacetylene fire, by contrast, has an strength of merely about 103W/cm2.
TYPES OF LASER-
( I ) THE RUBY LASER
( II ) THE HELIUM NEON LASER
( III ) THE LEVEL SOLID STATE LASER
( IV ) THE CARBON DIOXIDE LASER
( V ) DYE LASER
( VI ) SEMICONDUCTOR LASER
The first optical maser to be operated successfully was the ruby optical maser which was fabricated by MAIMAN in 1960. It consists of a individual crystal of ruby whose terminals are level and on of it is wholly silvered and the other partly silvered ; the two terminals therefore form a resonating pit. A flash lamp is used to excite the Cr atoms to a higher energy degree. The aroused atoms are unstable, so at a given instant some of them will return to the land province by breathing a photon in the ruddy part of the spectrum. The photon bounces back and 4th many times between mirrors at opposite terminals of the optical maser tubing. This photon can excite the emanation of photons of precisely the same wavelength from other aroused Cr atoms ; these photons in bend can excite the emanation of more photons, and so on. because the light moving ridges are in stage -that is their upper limit and minima coincide-the photons heighten one another, increasing the power with each transition between the mirrors. One of the mirror is partly reflecting, so that when the visible radiation reaches the certain strength it emerges from the mirror as a optical maser beam. Depending on the manner of operation, the optical maser visible radiation may be emitted in pulsations or in uninterrupted moving ridges.
HELIUM -NEON LASER-
The He Ne optical maser was the first gas optical maser to be operated successfully ; the He Ne laser consist of a long discharge tubing filled with approximately 1 torr He and about 0.1 millimeter of mercury of Ne. The gas mixture He and Ne signifiers the lasing medium and this mixture is enclosed between the set of mirrors organizing a resonating pit ; one of the mirror is wholly reflecting and the other is partly reflecting so as to match out the optical maser beam.
The visible radiation from a gas optical maser as compared to that from solid province optical maser is found to be more directional and much more monochromatic. This is due to the assorted imperfectnesss present in the solids and besides the warming caused by the flash lamp. The gas optical maser are besides capable to provide a uninterrupted optical maser without the demand for luxuriant chilling agreements.
The disadvantage of utilizing internal mirrors is that the mirrors are normally eroded by the gas discharge and have to be replaced.Having the resonating chamber mirrors external to the optical maser pit besides provides for greater flexibleness. However, when the external mirrors are used, the terminals of a discharge tubing besides cause a loss due to reflaction, so polarize visible radiation base on ballss through the plane without contemplation loss.when such Windowss are used, the end product optical maser beam is polarized.
FOUR LAVEL SOLID STATE LASER-It consists of neodymium ions. Nd ions are exited to energy degrees above metastable energy degree with a life-time of about 0.25msecs.Laser action is obtained between the metastable energy degree and land energy degree.
Typical threshold of a few hundred watts uninterrupted wave power inputs are required for attainment of population inversion. Output powers of several hundred Wattss have been obtained by utilizing several optical maser rods in cascade.
THE CARBON DIOXIDE LASER-
Carbon dioxide optical maser is much more efficient than other gas optical masers. In this optical maser one makes the passage between a rotational sublevel of a vibrational degree and rotational sublevel. The add-on of N2 gas to the C dioxide gas is seen to increase the efficiency of the C dioxide optical maser. Thus the N molecules are excited to the upper vibrational bed and it is seen that the energy difference between this bed and vibrational land degree of the N molecule lucifers really good with the energy required to excite the C dioxide molecule to the upper optical maser degree. Therefore there is really efficient transportation of energy between a N molecule and a C dioxide molecule.
The wavelength at which CO2 optical masers lase falls in the set where atmospheric fading is really small. Hence C dioxide optical maser should besides happen applications in unfastened bed communications system. It besides be utile in optical radio detection and ranging system.
DYE LASERS-Dyes used in optical masers are organic substances which absorb in the close UV, seeable, or the close infrared parts of the electromagnetic spectrum. Because of surface assimilation of visible radiation, dye molecules get exited from the land province S0 to higher vibrational rotational degrees of the following electronic province S1. Because of thermic redistribution in the degrees in the degree S1 ( which takes topographic point in times of about 10-11sec ) , most of the dye molecules drop down to the lowest vibrational degree to any higher lying vibrational sublevels of S0. This is termed as fluorescence. The life-time for S1 is about 10-9sec.hence the peak wavelength of the emitted fluorescence spectrum is higher than that of the soaking up spectrum.
Molecules from province S1 can besides do a nonradiative relaxation to the three degree T1 ; this is referred to as inter system traversing. First this procedure leads to a population of degree S1 which is the upper optical maser degree. Second the soaking up spectrum of T1-T2 normally overlaps the emanation spectrum of S1-S2, therefore taking to the loss at the wavelength matching to the optical maser emanation. In fact this loss can be so strong as to even forestall laser oscillation.
If we form a junction between p-type and n- type semiconducting material so the extra negatron in the n type part tends to flux across the junction into the p-type part and extra holes in the p part tends to flux to the n part. This creates an electric field opposing this flow and the flow Michigans.
If we connect the P type semiconducting material to the positive terminus of the direct current beginning and the n type to the negative terminus so one produces a flow of negatrons and holes into the junction part
.these negatrons and holes may recombine to bring forth radiation. This amounts to the deexcitation of an negatron from the conductivity set to the valency set. If the current is big plenty 1 may hold laser actions.
PLASMA-plasma is the 4th province of affair. It is the most common signifier of affair. Plasma which is in the stars and in the tenuous infinite between them makes up
the seeable existence and possibly most of that is non seeable.
On the Earth island upon which we live is made up of ordinary affair. By and large we find the three different provinces of affair which are solid liquid and gas. We learnt to work, play and rest utilizing these familiar provinces of affair. Sir William Crookes an English physicist identified a 4th province of affair, now called plasma in 1879.plasma temperatures range from comparatively cool to really hot, and densenesss range from tenuous ( like dawn ) to really heavy ( like the cardinal nucleus of star ) .ordinary solids liquids and gasses are both electrically impersonal and cool or dense to be in a plasma province.
The word plasma was foremost used to ionise gas by Dr Irvin Langmuir, an American chemist and physicist in 1929.
Plasma consists of a aggregation of free traveling negatrons and ions, atoms that have lost negatrons. Energy is needed to deprive negatrons from atoms to do plasma. The energy can be of assorted beginnings, thermic electrical or light ( ultraviolet visible radiation or intense seeable visible radiation from a optical maser ) with insufficient prolonging power plasma recombine into impersonal gas.
Plasma can be accelerated or steered by magnetic or electric Fieldss, Which allows it to be controlled and applied. Plasma research has yield a greater apprehension of the existence. It provides many practical utilizations. New fabricating techniques, consumer merchandises. The chances of abundant energy, more efficient lightening, surface cleansing, waste remotion and many more application subjects.
LASER PLASMA INTERACTION-
The procedure of interaction of optical maser plasma requires really high energy. This is due to the fact that unless the karyon have really high kinetic energies, the C repulsive force will non let them to come sufficiently near for interaction to happen. The temperature required are normally ~100 million 0K, and at such a high temperature the affair is in a to the full ionized province and its parturiency causes laser plasma interaction.
The formation and development of plasma produced during the interaction of a high power beam with solid insulators are subjects of practical housemans.
The experiment was carried out at the Rutherford Appleton Laboratory, using the 100 TW Nd Glass Vulcan optical maser operating in the chirp pulse elaboration manner. The affaire d’honneur CPA constellation was employed, supplying two CPA pulsation with adjustable comparative relay sat PS preciseness. Each of the end product beams delivered about 50J in 1.2 PS ( FWHM ) continuance. By utilizing off axis parabolas the beam were focused down, on different marks to descry of beams interacted with the He gas a supersonic nose driven at 50bar force per unit area. The other CPA beam was employed to bring forth the investigation proton beams by enlightening it onto a 10 micro m Au foil. The sensor of 2-3 centimeter from the gas jet. In the status of the experiment this provides a multi-frame temporal scan of the interaction for upto 50 PS in a individual shooting. The clip of reaching of the proton of a given energy at the interaction pint was controlled by the comparative clip of reaching of the split CPA beams on their several finish.
RESULTS AND DISCUSSION-
The typical consequences were obtained from plasma glass interaction. The frames are increased in go uping order of the optical maser energy.
The plasma was appeared in contact with glass surface. The plasma was spread outing supersonically towards the optical maser beam.
The entry of the short pulsation into the field of position and its extension through the plasma were observed due to the coevals of an instantaneous negatron depleted ion channel under the action of the strong radial ponder motor force of the optical maser. The radial electric field nowadays in the positively charged ion channel detected the investigation proton outward from the optical maser axis, making a negative shadow of the channel over the RCF. The proton projection channels are a slug shaped channel with crisp boundary, and a white channel with a dark line on the axis.
The image shown is the snapshot of the plasma taken during the extension of the optical maser pulsation through the extension of the optical maser pulsation through the gas pre ionized by the prepulse. The characteristics mentioned above are imprinted in the proton investigation cross subdivision due to the consequence of the radial field environing the extension axis at assorted phases of plasma development during or instantly after the pulse extension. At even later times the development of quasi- periodic transitions inside the channel was observed. These constructions evolved into round constructions which were observed to disintegrate on hydrodynamic clip graduated tables.