Abstract
The sealed neutron tube shell dissection process utilizing the traditional lathe turning method suffers from low efficiency and high cost due to the frequency of replacement of the diamond knife. In this study, a hybrid dissection method is introduced by combining the continuous-wave (CW) laser for efficient tangential groove production with an ultra-short pulse laser for delamination scanning removal. In this method, a high-power CW laser is firstly employed to make a tapered groove on the shell’s surface, and then a femtosecond pulse laser is used to micromachine the groove in order to obtain a cutting kerf. The thermal field was theoretically investigated in a finite element model. The simulation results show that the width of the area of temperature exceeding 100 °C is 1.9 mm and 0.4 mm with rotating speeds of 20 rad/s and 60 rad/s, respectively. In addition, a 2 mm deep slot in the 25 mm diameter tube was successfully produced in 1 min by a kilowatt fiber laser, and a 500-femtosecond pulse laser was employed to cut a plate with a material removal rate of 0.2 mm3/min. By using the hybrid method, the cutting efficiency was improved about 49 times compared to the femtosecond laser cutting. According to the simulation and experimental results, this method provides a high-efficiency and non-thermal cutting technique for reclaimed metallic neutron tube shells with millimeter-level thick walls, which has the advantages of non-contact, minimal thermal diffusion, and no effect of molten slag. It is indicated that the hybrid dissection method not only offers a new solution for thick neutron tube shell cutting but also extends the application of laser cutting techniques.
Highlights
The neutron tubes based on 2 H(d,n)3 He(D-D) or 3 H(d,n)4 He(D-T) fusion reactions to generate monochromatic neutrons have been widely applied in the fields of neutron radiography [1,2,3], borehole logging [4], coal analysis [5], searching for water [6], etc
The deuterium (D) and tritium (T) ions extracted from the ion source are firstly accelerated by high voltage electric field, and focused and bombarded to the ion target, producing high energy neutrons
By combining continuous-wave laser efficient tangential grooving with ultra-short pulse laser delamination scanning removal, a new dual laser beam asynchronous cutting method is presented for the efficient dissection of neutron tube shells with thick metallic walls
Summary
The neutron tubes based on 2 H(d,n) He(D-D) or 3 H(d,n) He(D-T) fusion reactions to generate monochromatic neutrons have been widely applied in the fields of neutron radiography [1,2,3], borehole logging [4], coal analysis [5], searching for water [6], etc. The process is messy and characterized by huge quality variation in terms of the kerf width and striations It is not an appropriate approach for the dissection of neutron tube shells. The high-power laser cutting process is highly efficient but with a large thermal diffusion region, and the ultra-short pulse micromachining process is a non-thermal technique but with ultra-low material removal rates: both of them are not suitable for the dissection of neutron tube shells. By combining continuous-wave laser efficient tangential grooving with ultra-short pulse laser delamination scanning removal, a new dual laser beam asynchronous cutting method is presented for the efficient dissection of neutron tube shells with thick metallic walls. A kilowatt continuous-wave fiber laser and a femtosecond pulse laser were employed to process a tube part and plate sheet in the experiments to certify the novel method
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