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Abstrak :
Characterizations have been performed on single stage Transversely Excited Nitrogen Laser of Blumlein type. Optical cavity arrangement is varied prior to measurement which shows no significant increase in energy on both configurations of inserting a mirror only and a pair of mirror and a quartz parallel plate. Frequency repetitions respond reveals a small drop in energy at higher frequency i.e. 10 Hz by a factor of 20%. N2 flow rate consideration behaves on the similar way like pressure profile. At higher supply voltage maximum energy is shifted to higher N2 flow rate. A similar tendency occurs on pressure curve but with more pronounced maximum energy. Higher supply voltage would shift maximum energy to higher N2 pressure. Other operating conditions have been kept constant. Beam divergence measurement has given 1,87 mrad on vertical direction and 9,32 mrad on horizontal axis. However, beam cross section experiences a -10° tilt against horizontal reference. This may happen due to a slight twist on main electrodes. Measurements on different date have showed inconsistent results. Major cause is suspected on using different N2 cylinder, replacement on the gauge pressure, and crater creation on HV side spark gap electrode.

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A spectrometer application of time resolved method spectroscopy has been used in many times of experiment on physical of atomic, molecule and ionized plasma behavior. This paper is completed to make experimental work easier in reading and processing of datum. Using PC and interfaces can make signal convert to digital signals and it can save for long time in a very popular magnetic media. So, we can recall specific signal datum to re analyze or compare with new datum. Beside that, the spectrum of any saved datum can be printed many times. This half automatic spectrometer consists of: - Delay and Gating time, - Sample and Hold. - Analog to Digital Conversion ( ADC ). This design consists some modules of software that have been written in C language, and have compiled by a Borlan C compiler.

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ABSTRAK
An N2 laser system that consists of transversely excited atmospheric (TEA) oscillator and transversely excited (TE) amplifier has been designed and constructed. The laser system employs single common spark gap for both oscillator and amplifier. The optimum operating voltage is 15 kV at 2 Hz repetition rate. The measured energy of the output oscillator-amplifier system has maximum value of 55 pJ and beam divergence of 2 mrad horizontally and 1 mrad vertically.

Synchronization between the oscillator and amplifier was achieved by varying the gas pressure in amplifier tube, inductance between oscillator and spark gap as well as the optical path between the oscillator and amplifier. The result of its characterization showed that this system is capable to producing BOO % amplification in a single pass.

Abstrak :
Computer simulation program has been developed on the basis of Liapunov approach for the study of MRAC technique applied to pressure control for a vacuum system. Both proportional and integral feedback as well as disturbance feedforward is considered in the closed-loop system. The simulation result obtained with a personal computer demonstrates that this MRAC technique is feasible and provides effective and satisfactory control despite its poor initial control policies and wide range of choice for the adaptive gains. For a series of step disturbance, MRAC resulted in continually improved control with very good agreement obtained between process and reference model responses after the second disturbance.

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A fluorescence spectrometer, with gating PMT (Photo Multiplier Tube) has been designed and constructed for the observation of Time Resolved Spectroscopy. Employed as a source far the fluorescence spectrometer a pulsed N2 lasers with about 5-nanosecond pulse width and 400-kilowatt power. Gating PMT carries out the sampling. In this method some of the dynodes of the PMT are being biased at voltages below normal operating voltage, while the other dynodes are held at their normal voltages. Sampling pulses generated by avalanche transistor are fed into the dynodes of the lower voltage to operate the PMT. A variable delay circuit of the order of nanosecond with respect to the N2 lasers pulse delays the sampling pulses. The output of the PMT is read on an oscilloscope and the lifetime of the fluorescence can be obtained by plotting the output of the PMT vs. the delay time.

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ABSTRACT
A vacuum chamber has been designed and constructed for the observation the primary plasma and secondary plasma which is generated by the bombardments of brass by N2 Laser beam with about 5 ns pulse width and 1 1W power.

The Radius and spectral emission of the resulting secondary plasma of the brass sample at the surrounding gas pressure range 2 and 8 torr in N2, is presented.

This study can be developed to generated plasma and it can used for the analysis the composition the sample irradiated by N2 laser beam.

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The design and construction of eight-bit tune delay autocorrelator is discussed, suitable for use in photon correlation experiments. The sampling time of the correlator can be varied from 1 usec to 100/usec, devide into a number ( typically 256 ) channels (time interval). The instruments records the number of pulses occuring in each sampling time and is stored in location memory in a RAM-BANK. The data is stored in binary form, the data can be converted to analog form by digital to analog converter and is displayed on an oscilloscope.

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ABSTRACT
The principles of frequency stabilization is to keep constant the optical path length in laser cavity by controlling the laser- tube length. In this system used temperature servo control to control the laser tube length.

As reference to an error derived by a sensitive frequency discriminator. Basically the operation of this sensitive frequency discrimantor utilized the longitudinal Zeeman Laser, which splits atomic gain profile.

When a longitudinal magnetic field is applied to an internal mirror of single mode He-Ne Laser, the active medium acquires a negative circular dichroism. There fore the intensity of the left cicular polarization (LCP) output of the, laser will be different from the intensity of the right circular polarization (RCP) output and only when the two are simmetrically disposed about the center line will their intensities be equal. This intensity difference as feedback can be detected by passing the output beam throught Wallaston prism and the two orthogonally polarized beams are received by two identical photodiodes. The difference between the output of photodiode as amplified and the resulting signal is passed throught a system controller (PID) before it is fed back as heating or cooling current of peltier elements. This current controls the resonator length thermally and lock the laser frequencies of the two polarized beam symmetrically on either side of the profile.

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A computerized intensity detection system has been designed and constructed using single board TK-85 microprocessor system. Two types of hardware architectures, Address Mapped and Memory Mapped Input-Output systems are utilized as Input module from light detector and Output module to X-Y recorder, respectively. A performance test on the computer system has shown that the system hardware and software function properly with consistent gain -of l.36O. An educational grating- used for the overall performance test has also indicated instrumental accuracy consistent with design limitation. A preliminary application of this system in light scattering experiment has exhebited qualitative features in the angular distribution of the scattered light intensity which are consistent with theoritical prediction.

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Many alkali halides crystal develop new absorption bands upon exposure to ionizing radiations. the absorbing centers responsible for these bands are called "Color-Centers". De Boer 1937 was proposed a model for one of the color centers, is called the "F-Center" which consisted essentially of an electron trapped at the position a missing halogen ion (halogen ion vacancy). with the recognition of the highly mportant influence of structural imperfection or defect (Frenkel and Schottky defects) on the physical properties of alkali cyrstal it seemed clear that the imperfection were involved in the production and constitutional of the color centers.

in this experiment, the formation and decay of color centers under N2 laser light (λ=337,1 nm) irradiation has been studied on pure KBr crystal in the romm temperature using the "Oscilloscopiic Method". the F band reach maximum hights in optical density at the end of the radiation pulse. from this experiment were obtained:

the peak position of the F-band at the wavelength 620nm, or t the energy E=2,00 ev.

the half-width of the F-band however, was : W= 0,241 ev.

Decay time constant = 16,8 , and the concentration of the F center was: N = 1,6 x 10(^15) per cc.