Local tempering of welds in cylindrical shells with local heating

1975 ◽  
Vol 9 (3) ◽  
pp. 335-338
Author(s):  
G. V. Plyatsko ◽  
V. N. Maksimovich ◽  
Z. I. Goryacheva ◽  
D. P. Bolotyuk
Keyword(s):  
Local Heating ◽  
Cylindrical Shells

Numerical Investigations on Bearing Capacity of Grid-Stiffened Cylindrical Shells Subjected to Local Laser Irradiation

2013 ◽  
Vol 444-445 ◽  
pp. 72-76
Author(s):  
Hai Hong Liu ◽  
Lian Chun Long
Keyword(s):  
Numerical Simulation ◽  
Temperature Distribution ◽  
Bearing Capacity ◽  
Laser Irradiation ◽  
Irradiation Time ◽  
Local Heating ◽  
Initial Period ◽  
Cylindrical Shells ◽  
Thin Wall ◽  
Stiffened Cylindrical Shells

Grid-stiffened cylindrical shells are widely applied in aviation and aerospace engineering. Bearing capacities of grid-stiffened cylindrical shells will be reduced by local heating. In this study, numerical simulation method is applied to deduce the temperature distribution of the grid-stiffened cylindrical shells subjected to high power laser irradiation. Temperature dependent aluminum alloy properties are fully considered in the process of numerical simulation. Comparing to smooth thin-wall cylindrical shells, the effect of ribs size to temperature distribution is studied. As the material properties varying with temperature, the temperature rising rate is higher at the initial period when cylindrical shell is subjected to laser irradiation. The temperature rising rate gradually reduces with irradiation time increasing. Buckling analysis was performed to obtain the buckling bearing capacity and the effect of local heating on grid-stiffened cylindrical shells subjected to local heating.

UHV-TEM studies of laser-induced damage

1991 ◽  
Vol 49 ◽  
pp. 632-633
Author(s):  
T.S. Savage ◽  
R. Ai ◽  
D. Dunn ◽  
L.D. Marks
Keyword(s):  
Surface Science ◽  
Rapid Heating ◽  
Local Heating ◽  
Routine Practice ◽  
Transmission Electron ◽  
Northwestern University ◽  
Laser Induced Damage ◽  
Set Up ◽  
Focusing Lens ◽  
Diffusion Of Impurities

The use of lasers for surface annealing, heating and/or damage has become a routine practice in the study of materials. Lasers have been closely looked at as an annealing technique for silicon and other semiconductors. They allow for local heating from a beam which can be focused and tuned to different wavelengths for specific tasks. Pulsed dye lasers allow for short, quick bursts which can allow the sample to be rapidly heated and quenched. This short, rapid heating period may be important for cases where diffusion of impurities or dopants may not be desirable.At Northwestern University, a Candela SLL - 250 pulsed dye laser, with a maximum power of 1 Joule/pulse over 350 - 400 nanoseconds, has been set up in conjunction with a Hitachi UHV-H9000 transmission electron microscope. The laser beam is introduced into the surface science chamber through a series of mirrors, a focusing lens and a six inch quartz window.

Point-Cathode Electron Gun Using Electron-Beam Bombardment for Cathode Tip Heating

1990 ◽  
Vol 48 (1) ◽  
pp. 198-199
Author(s):  
Ryo Iiyoshi ◽  
Susumu Maruse ◽  
Hideo Takematsu
Keyword(s):  
Electron Beam ◽  
Tungsten Wire ◽  
Local Heating ◽  
Electron Gun ◽  
Original Position ◽  
Beam Power ◽  
Radius Of Curvature ◽  
High Brightness ◽  
Beam Focusing ◽  
Time Operation

Point cathode electron gun with high brightness and long cathode life has been developed. In this gun, a straightened tungsten wire is used as the point cathode, and the tip is locally heated to higher temperatures by electron beam bombardment. The high brightness operation and some findings on the local heating are presented.Gun construction is shown in Fig.l. Small heater assembly (annular electron gun: 5 keV, 1 mA) is set inside the Wehnelt electrode. The heater provides a disk-shaped bombarding electron beam focusing onto the cathode tip. The cathode is the tungsten wire of 0.1 mm in diameter. The tip temperature is raised to the melting point (3,650 K) at the beam power of 5 W, without any serious problem of secondary electrons for the gun operation. Figure 2 shows the cathode after a long time operation at high temperatures, or high brightnesses. Evaporation occurs at the tip, and the tip part retains a conical shape. The cathode can be used for a long period of time. The tip apex keeps the radius of curvature of 0.4 μm at 3,000 K and 0.3 μm at 3,200 K. The gun provides the stable beam up to the brightness of 6.4×106 A/cm2sr (3,150 K) at the accelerating voltage of 50 kV. At 3.4×l06 A/cm2sr (3,040 K), the tip recedes at a slow rate (26 μm/h), so that the effect can be offset by adjusting the Wehnelt bias voltage. The tip temperature is decreased as the tip moves out from the original position, but it can be kept at constant by increasing the bombarding beam power. This way of operation is possible for 10 h. A stepwise movement of the cathode is enough for the subsequent operation. Higher brightness operations with the rapid receding rates of the tip may be improved by a continuous movement of the wire cathode during the operations. Figure 3 shows the relation between the beam brightness, the tip receding rate by evaporation (αis the half-angle of the tip cone), and the cathode life per unit length, as a function of the cathode temperature. The working life of the point cathode is greatly improved by the local heating.

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