Differential testing method of power density distribution of electron beam

Abstract

The invention discloses a differential testing method of power density distribution of an electron beam. The differential testing method comprises the following steps: firstly arranging a testing system; designing a Faraday cup sensor; enabling the electron beam to move along a path which is parallel to the length direction of a slit, wherein the path is a forward stroke scanning path, and signals acquired during the process are effective signals and are used for follow-up processing; enabling the electron beam to move in reverse direction after the electron beam completely passes through theslit, wherein the path is a reverse stroke scanning path, and the signals acquired during the process are invalid signals and are not stored; repeating the steps and enabling projection spots of the electron beam on a tungsten sheet to move from one side to the other side of the slit; setting a current density distribution function of the electron beam as f(x,y), and then getting a power density distribution function g(x,y) which equals f(x,y)*Ua; and performing forward stroke scanning n times during the whole deflection scanning, then getting n fi(x)s, using computer software to draw the n fi(x)s into a current density distribution graph and finally getting a power density distribution graph and the diameter. The differential testing method disclosed by the invention does not need to usea new metal test sample to measure power density distribution every time, thereby saving the testing cost.

Description

technical field [0001] The invention belongs to the technical field of electron beam processing, in particular to a differential test method for electron beam power density distribution. Background technique [0002] For an electron beam welding machine, in order to study the difference between the theoretical design and the actual electron gun, the influence of factors such as the stability of the electron gun power supply system and the change of vacuum degree on the diameter of the electron beam spot and the distribution of power density, and the effect of the size and position of the beam spot on The influence of weld seam formation needs to study the characteristics of the beam accurately, and quantitatively measure the position, diameter and distribution of the beam power density of the electron beam focus. [0003] At present, there are small beam current empirical method, AB test method, probe test method, threshold power density test method and DIABEAM test method (...

AI Technical Summary

Problems solved by technology

Among them, the small beam empirical method can only roughly determine the focus position, and the operator's experience has a greater influence; the Arata-Beam Teat Method (AB method) invented by Professor Arata of Japan is to place metal sheets vertically at different heights, in a Sawtooth slope shape, the electron beam sweeps along the slope, by measuring the traces of the electron beam melting width on the metal sheet, the space diameter and focus position of the electron beam at different working distances are measured, the measurement error of the melting width is large; the probe type The test method is only suitable for the measurement of small power density due to the small diameter of the probe, which is burned quickly under high power density. At the same time, there is secondary electron emission, which will affect the measurement accuracy; the threshold power density test method is based on the Faraday cylinder , but it relies on the assumption that the power density distribution is circumferentially symmetric, which has limitations; the DIABEAM test method can measure the beam spot diameter and electron beam energy density distribution of relatively high-power electron beams, and the size of the small hole area for collecting current will affect Measurement accuracy, and the splashed metal is easy to block the small hole

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