Design of laser beam divergence angle program control system

2009 ◽  
Author(s):  
Chuang-xin Zhang ◽  
Yang Jiao ◽  
Shi-guang Yang ◽  
Xiao-quan Sun
Keyword(s):  
Control System ◽  
Laser Beam ◽  
Program Control ◽  
Beam Divergence ◽  
Divergence Angle ◽  
Beam Divergence Angle

Measuring Pulsed Laser Beam Divergence Angle Via Dual-Frame Image Fusion

2014 ◽  
Vol 41 (7) ◽  
pp. 0708002
Author(s):  
王劲松 Wang Jinsong ◽  
朱大钊 Zhu Dazhao ◽  
李延风 Li Yanfeng ◽  
安志勇 An Zhiyong
Keyword(s):  
Laser Beam ◽  
Image Fusion ◽  
Pulsed Laser ◽  
Beam Divergence ◽  
Divergence Angle ◽  
Dual Frame ◽  
Beam Divergence Angle ◽  
Pulsed Laser Beam

Analysis of the Effect of Beam Divergence Angle on Back-Streaming Electron Region in Ion Source for EAST-NBI

2017 ◽  
Author(s):  
Chundong Hu ◽  
Mingshan Wu ◽  
Yahong Xie ◽  
Jianglong Wei ◽  
Ling Yu
Keyword(s):  
Cross Section ◽  
Secondary Electron Emission ◽  
Circular Cross Section ◽  
Ion Source ◽  
Beam Divergence ◽  
Divergence Angle ◽  
Beam Extraction ◽  
Emission Surface ◽  
Ion Emission ◽  
Beam Divergence Angle

During the process of beam extraction in positive ion source under high voltage region, a large number of electrons are produced in the gaps of grids. After back-streaming acceleration, these electrons go back to arc chamber or impinge grids and heat electron dump or grids, which are harmful for the safety of ion source. Under the situation of poor beam extraction optics, a large part of the primary beam ions bombard the surface of suppressor grid. And this process produces a large number of electrons. Due to the huge extracted voltage, the secondary electron emission coefficient of the suppressor grid surface is also great, when beam ions bombard on it. As a result, the grids’ current grows. The curvature of ion emission surface and equipotential surface nearby are mainly connected to the perveance and plasma grid geometry. In order to optimize the beam performance of high current ion source and increase the mean arc efficiency, the plasma grid of accelerator is already replaced from circular cross section grid to diamond cross section grid. As a result, the shape of ion emission surface is only connected to the perveance. According the measurement of the current of suppressor grid and the calculation of the perveance of the corresponding shoot, we can analyze the effect of beam divergence angle on back-streaming electron. When the beam divergence angle increases, the number of back-streaming electrons increases rapidly, and grids current changes significantly, especially the current of gradient grid and suppressor grid. The results can guide the parameters operating on the ion source for EAST-NBI and find the reasonable operation interval of perveance and the best one to ensure the safety and stable running of the ion source, which has great significance on the development of long pulse, high power ion source.

Analysis of the Effect of Beam Divergence Angle on Back-Streaming Electron Region in Ion Source for EAST-Neutral Beam Injection

2018 ◽  
Vol 4 (3) ◽  
Author(s):  
Hu Chundong ◽  
Wu Mingshan ◽  
Xie Yahong ◽  
Wei Jianglong ◽  
Yu Ling
Keyword(s):  
Ion Beam ◽  
Ion Source ◽  
Neutral Beam Injection ◽  
Beam Divergence ◽  
Neutral Beam ◽  
Divergence Angle ◽  
Beam Extraction ◽  
Beam Injection ◽  
Back Plate ◽  
Beam Divergence Angle

During the process of beam extraction in positive ion source under high voltage region, a large number of electrons are produced in the gaps of grids. After back-streaming acceleration, these electrons go back to arc chamber or impinge grids and then heat back plate or grids, which are harmful for the safety of ion source. Under the situation of poor beam extraction optics, a large part of the primary beam ions bombard the surface of suppressor grid (SG). And this process produces a large number of electrons. Due to the huge extracted voltage, the secondary electron emission coefficient of the SG surface is also high. As a result, the grids' current grows. According to the measurement of the current of SG and the calculation of the perveance of the corresponding shoot, the effect of ion beam divergence angle on back-streaming electrons can be analyzed. When the beam divergence angle increases, the number of back-streaming electrons increases rapidly, and grids' current changes significantly, especially the current of gradient grid and SG. The results can guide the parameters operating on the ion source for Experimental Advanced Superconducting Tokamak-neutral beam injection (EAST-NBI) and find the reasonable operation interval of perveance and to ensure the safety and stable running of the ion source, which has great significance on the development of long pulse, high power ion source.

VARIATION OF BEAM DIVERGENCE AS A FUNCTION OF DISCHARGE GAP DISTANCE FOR A NITROGEN LASER

2009 ◽  
Vol 23 (11) ◽  
pp. 1457-1466 ◽  
Author(s):  
H. GOLNABI ◽  
M. R. NOURANI
Keyword(s):  
Laser Beam ◽  
Beam Width ◽  
Propagation Distance ◽  
Beam Divergence ◽  
Divergence Angle ◽  
Nitrogen Laser ◽  
Geometrical Method ◽  
Short Side ◽  
Discharge Gap

A simple geometrical method is used here for divergence determination of a TEA N 2 laser. Using beam cross-section (rectangle) monitoring on the fluorescence paper and geometrical method, the laser beam divergence is determined. Variations of the laser beam width (W) and height (H) with respect to the gap distance are investigated for propagation distances of 10, 30, and 50 cm from the laser aperture. For the 0.52 mm gap, the beam width (W) at a distance of 10 cm is about 2 cm and height is also 2 cm (H = 2 cm ), while both increase to about W = 3.125 cm , and H = 2.4 cm at a distance of 50 cm. At 50 cm distance, for a gap distance range of 0.52 mm, W = 3.125, H = 2.4 cm , which increases to W = 18.5 cm , H = 3.6 cm for gap distances of 1.3 mm. Variations of the defined aspect ratio (H/W) as a function of electrode separation and beam propagation distance are also investigated. Variation of the divergence angle along the short and long side of the rectangular beam is investigated. The divergence angle along the long side for the 0.52 mm gap is about 0.0281 rad, and increases with gap value, and for the 1.3 mm gap is 0.284 rad, corresponding to an average divergence of 0.156 rad in this range. The average divergence in the short side is about 0.01 rad, which is much smaller than the divergence angle along the long side (0.156 rad). This study shows that the discharge gap distance, in addition to its important role in N 2 laser output power, it also plays an important role in the beam divergence, especially in the horizontal plane.

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