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Fabrication of resonant optical waveguide biosensors using electron gun depositionsCornell, Timothy Allen. January 2005 (has links)
Thesis (M.S.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains iv, 94 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 93-94).
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Low-noise electron guns for television pickup tubes /Campbell, R. M. January 1966 (has links)
No description available.
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Carbon nanotubes as electron gun sourcesMann, Mark January 2008 (has links)
No description available.
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The development of an electron gun for performing ultrafast electron diffraction experimentsErasmus, Nicolas 12 1900 (has links)
Thesis (MSc (Physics))--Stellenbosch University, 2009. / ENGLISH ABSTRACT: This thesis aims to comprehensively discuss ultrafast electron di raction and
its role in temporally resolving ultrafast dynamics on the molecular level. Theory
on electron pulses and electron pulse propagation will be covered, but the
main focus will be on the method, equipment and experimental setup required
to generate sub-picosecond electron pulses, which are needed to perform time
resolved experiments. The design and construction of an electron gun needed
to produce the electron pulses will be shown in detail, while preliminary pulse
characterization experiments will also be illustrated. An introduction into the
theory of electron diffraction patterns and how to interpret these diffraction
patterns will conclude the thesis. / AFRIKAANSE OPSOMMING: Hierdie tesis het ten doel om ultravinnige elektrondi raksie deeglik te bespreek
asook die rol wat dit speel om ultravinnige tyd-dinamika op 'n molekulêre vlak
op te los. Die teorie van elektonpulse en die voortplanting van elektronpulse sal
gedek word, maar die fokus sal op die metode, gereedskap en eksperimentele opstelling
wees wat benodig is om sub-pikosekonde elektronpulse te genereer. Die
ontwerp en konstruksie van 'n elektrongeweer, wat benodig word om elektronpulse
te produseer, sal in detail bespreek word, terwyl aanvanklike pulskarakterisasie
eksperimente ook illustreer sal word. 'n Inleiding tot die teorie van
elektrondi raksie patrone en hoe om hulle te interpreteer sal die tesis afsluit.
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MODELING AND FABRICATION OF LIGHTWEIGHT, DEFORMABLE MIRRORS SUBJECTED TO DISCRETE LOADINGRoche, Michael E. 01 January 2001 (has links)
The push towards larger diameter space telescope mirrors has caused the space industry to look at lightweight, deformable alternatives to the traditional monolithic mirror. One possible solution to the dilemma is to use the piezoelectric properties of certain materials to create a lightweight, deformable mirror. Current piezoelectric deformable mirror designs use individual actuators, creating an immensely complex system as the mirrors increase in size. The objective of this thesis is to aid in the design and development of lightweight, deformable mirrors for use in space based telescopes. Two topics are considered to aid this development. A doubly curved, lightweight, bimorph mirror is investigated. The fabrication method entails forming a thin film piezoelectric polymer into a doubly curved shape using a specially designed forming machine. The second topic entails the finite element modeling of a composite mirror substrate with a piezoceramic actuator backing. The model is generated using a meshing program designed to generate off-centered spot loads of electric potential. These spot loads simulate the actuation due to an electron gun. The effects of spot location and size on mirror deformation are examined.
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CHARACTERIZATION OF AN ELECTRON GUN CONTROLLED MULTIPLE SPATIAL REGION PIEZOELECTRIC THIN FILMMacke, Benjamin Tyler 01 January 2003 (has links)
Piezoelectric bimorph thin films may hold solutions for many future applications, such as lightweight deployable mirrors and inflatable struts. Non-contact actuation by an electron gun has shown promise in preventing issues that arise from attaching many wire leads to a thin film surface. This study investigates piezoelectric bimorph thin film response to electron gun actuation when covered with multiple spatial regions of control. Desired parameter ranges are found that will lead to predictable control under certain circumstances. Under such circumstances, film response is influenced almost solely by the primary electrons incident on the film, and secondary electrons have negligible effect. Such information is vital before attempting closed loop control of a thin-film piezoelectric mirror with multiple electrodes.
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Construção de um acelerador de elétrons de 20KeV: aplicação ao estudo dos polímeros. / Development of a 20KeV electron gun for the study pf polymers.Sandonato, Gilberto Marrega 05 August 1983 (has links)
Construiu-se um acelerador de elétrons de baixa energia (Máximo de 20 KeV). Como fonte de elétrons utilizou-se um canhão de elétrons de cinescópio preto e branco, ou seja, com um único emissor termiônico. A energia do feixe eletrônico pode ser continuamente variada desde 0 a 20 KeV. A corrente eletrônica pode ser variada desde um valor mínimo de 10-12A a 3μA, permanecendo constante no tempo uma vez fixado o seu valor. Através da focalização ou desfocalização da imagem do feixe de elétrons, é possível variar-se a área irradiada desde um diâmetro mínimo de 1 milímetro a um máximo de 6 cm. A pressão final atingida nas câmaras de vácuo foi da ordem de 10-7Torr. Durante o funcionamento do canhão de elétrons, o cátodo do mesmo é danificado devido ao bombardeamento de íons em sua superfície. Para examinarmos o grau de danificação causado por este bombardeamento iônico, basta focalizarmos e examinarmos a imagem de feixe eletrônico sobre uma tela luminescente. Deve-se ressaltar que todo o acelerador de elétrons foi construído a partir de materiais e componentes totalmente nacionais. O acelerador de elétrons foi aplicado para estudar efeitos de irradiação de elétrons em Teflon usando-se o método do Split Faraday Cup. Foram medidas correntes transitórias de carga e descarga e determinaram-se o alcance médio dos elétrons e o valor da condutividade induzida pela radiação. / We have constructed a low energy electron accelerator (maximum energy 20 KeV). A black and white kinescope electron gun, with a single thermionic emitter was used as an electron source. The energy of electron beam can be changed continuously from 0 to 20 KeV. The intensity of the current can be changed from a minimum of 10-12A to a maximum of 3μA, and can be maintained constant in time after its value has been fixed. The irradiated area can be changed from a diameter of 1 millimeter to a maximum of 6 centimeter, by focalizing or defocalizing the image of electron beam. The final pressure reached in vacuum chambers was 10-7Torr. During operation the surface of cathode of electron gun is damaged by ion bombardment. The degree of damage can be checked if the cathode image is focalized and examined on a luminescent screen. The accelerator was used to study electron irradiation effects in Teflon, employing the method of the Split Faraday Cup. Transient charging and discharging currents were measured. The average range of electrons of the electrons and induced conductivity were determined.
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The Study and Fabrication of High Efficiency Yb:YAG Ring LaserCheng, Kuo-Wei 21 July 2005 (has links)
In the past three decades, Nd:YAG has been the dominating high power solid-state laser gain medium. Compared with Nd:YAG, Yb:YAG has lower quantum defects which produces less heat so that it can reduce thermo-optical deformation. In addition, the achieved doping concentration can be 100%, and the absorption FWHM at 941 nm is 18 nm. Based on above listed advantages, Yb:YAG has the potential to replace Nd:YAG.
Using Yb:YAG as the laser gain medium in reentrant two-mirror laser cavity, we have succeeded in Yb:YAG ring laser and all the intracavity elements are coated by our electron gun deposition system.
The main purpose of my research is to continue the previous result (slope efficiency: 20.1%), and further increasing the slope efficiency of our ring cavity with different round-trip transmittance of couplers. Besides, we measured and analyzed the polarization of the planar and non-planar ring cavities. At present, the highest slope efficiency we achieved is 38.9% with a round-trip transmittance of 16.4%.
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A gridless, variable perveance Pierce electron gun.Foulis, Bruce David. January 1994 (has links)
This thesis covers the design and development of a modulated Pierce electron gun
used in the construction of experimental travelling wave tube (TWT) amplifiers. The
gun incorporated an open aperture switching electrode, positioned mid-way between
anode and cathode, to pulse the beam. This method of modulation did not have the
same adverse effects on electron trajectories as in the case of a conventional mesh
grid, but rather the electrode could be used to alter the focus conditions within the
gun and subsequently improve certain beam characteristics. Ion focusing effects
could also be eliminated with the electrode, allowing dual mode operation of the guns
without the complications normally associated with such a practice.
The switching electrode was simulated to ascertain its effect on electron trajectories
within the gun, using finite element analysis as well as an electron optics design
program. A test gun was constructed in a glass envelope in order to investigate the
performance of the new design. The glass gun allowed a beam analysis to be
performed, as well as thermal measurements to be made. Results from this gun
compared favourably with earlier simulations. The results of two metal/ceramic
construction TWTs are presented, showing the beneficial effects of the switching
electrode on the performance of the tubes as a whole, and the electrode's potential
to compensate for constructional anomalies.
The joining of metals to ceramic using active brazing techniques is also an important
aspect tackled by the thesis, with several innovative ideas being implemented in the
construction of the devices. A simple yet reliable electrical feed-through was
developed for those guns having a ceramic envelope.
Extensive work was also performed on the manufacture of impregnated tungsten
cathodes for use in the electron guns. Several test diodes, including a water-cooled
demountable test vehicle, were constructed to test the performance of the cathodes.
An analysis was performed on the patchy behaviour of some of the initial cathodes
to improve the preparation methods used in the laboratory. The emission results
obtained from the cathodes are documented, as is the successful incorporation of
several of them into the new modulated gun design. / Thesis (Ph.D.)-Univesity of Natal, Durban, 1994.
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The development of an experimental, low profile, broadband travelling wave tube amplifier.Vassilopoulos, Nicolaos. January 1994 (has links)
An experimental, field replaceable travelling wave tube (TWT) with low profile, TEM
transitions has been developed with the aim of combining the cost advantages of field
replaceable TWTs with the bandwidth advantages of TEM transitions. Field replaceable
TWTs are cheaper because their periodic permanent magnet (PPM) stacks (which are
expensive) are easier to produce and can be reused. Standard TEM transitions have a
high profile and prevent TWTs from being plugged into PPM stacks. The stacks of
packaged TWTs are therefore built onto the tubes, using split ring magnets, before the
tubes are potted. Upon failure, such tubes are discarded together with their focusing,
coupling and cooling structures.
Two types of low profile, TEM transitions were investigated: a ring and a plug transition.
In the former, the helix was joined to a metal ring that was sandwiched between two
ceramic rings in the vacuum envelope. Due to its high shunt capacitance, this transition
was narrowband. In the plug transition, the helix was joined to a small metal plug in the
wall of a ceramic tube. Plug transitions with a return loss of better than 10 dB over an
octave were made but some technological difficulties were encountered. Metal/ceramic
joining with active solder is therefore discussed.
The development of graphite attenuators was attempted but graphite of high enough
resistivity to achieve the attenuation and matching required was not available. Thin film
attenuators were therefore used instead. Some good attenuators were made but the
molybdenum films were sensitive to processing conditions.
An empirical procedure was developed to magnetize PPM stacks to a wanted profile.
The stacks that were designed and built resulted in good beam focusing. TWT tests
were made using an automated test station that was built. Maximum RF gains and
output powers of 20 dB and 43 dBm respectively were measured.
The TWT design, construction and testing was a combination of materials science and
microwave work. Some simulations were used to solve electromagnetic problems but
much of the work was practical, involving trial and error and many measurements. / Thesis (Ph.D.)-University of Natal, Durban, 1994
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