Pulse X-ray tube micro-focus point light source device and method

Abstract

The present invention discloses a pulse X-ray tube micro-focus point light source device and method, belonging to the field of pulsed rays, and the key points of the technical solution include a pulse power source, a transmission rod, an anode, a cathode, a point light source filter and a vacuum cavity, the transmission rod connects the pulse power source and the anode, the anode includes a conical rare earth metal material block, the cathode includes a ring-shaped steel sheet, the anode is horizontally arranged with the tip facing the cathode, the cathode is slidably connected to the inside of the vacuum cavity along the length direction of the vacuum cavity, and the inside of the vacuum cavity is slidably connected to the point light source filter along its length direction. The present invention achieves the effect that the size of the X-ray point source finally radiated can be on the order of hundreds of μm.

Description

Technical Field

[0001] The present invention relates to the field of pulsed rays, and more particularly to a pulsed X-ray tube micro-focus point light source device and method. Background Art

[0002] In pulse power device photography technology, in order to obtain X-ray point sources with a diameter of tens of microns, the method of using magnetic lenses to micro-focus electron beams for targeting is often used. Domestic and foreign laboratories have adopted many technical methods and carried out a large number of research projects and funding, but so far there have been no reports of X-ray point sources with a diameter of several hundred microns. Summary of the invention

[0003] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a pulse X-ray tube micro-focus point light source device and method, which adopts a cold cathode vacuum X-ray tube, uses a conical metal as an anode, and a circular steel sheet as a cathode, which is installed in a vacuum chamber to form a reflective target vacuum X-ray diode. The cold cathode has sharp corners or tips to promote the generation of field emission current; the design of the anode maximizes the intensity of the X-rays and minimizes the emission area.

[0004] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a pulse X-ray tube micro-focus point light source device, comprising a pulse power source, a transmission rod, an anode, a cathode, a point light source filter and a vacuum chamber, wherein the transmission rod connects the pulse power source and the anode, the anode comprises a conical rare earth metal material block, the cathode comprises a ring-shaped steel sheet, the anode is horizontally arranged with the tip facing the cathode, the cathode is slidably connected to the inside of the vacuum chamber along the length direction of the vacuum chamber, and the inside of the vacuum chamber is slidably connected to the point light source filter along its length direction.

[0005] By adopting the above technical solution, when the high-voltage positive pulse acts on the anode, the cathode field strength is very high. Due to field-induced emission, a ring-shaped electron beam will be generated in the cathode ring. After being accelerated by the electric field between the cathode and the cathode, it bombards the anode target and generates bremsstrahlung X-rays. This structure has the maximum X-ray transmission efficiency at an angle of 0 degrees. Through the fine processing of the anode target cone tip, the size of the X-ray point source can be in the order of hundreds of μm. Through the micro-focusing guidance of the cathode and the anode, a small focal spot X-ray point source is generated after interacting with the filter. Through measurement, the size of the point source is in the order of hundreds of microns, completing the micro-focusing effect of the X-ray point source.

[0006] Preferably, the anode includes a conical tungsten needle arranged in a conical shape toward the cathode.

[0007] By adopting the above technical solution, the conical tungsten needle arranged in a conical shape toward the cathode can increase the intensity of the X-rays, thereby making the emission area of ​​the X-rays as small as possible, thereby achieving micro-focusing of the X-ray power source.

[0008] Preferably: an enlarged portion forming a sharp edge is provided at the inner edge of the cathode.

[0009] By adopting the above technical solution, when the pulse wave acts on the anode, the cathode will generate a ring-shaped electron beam in the center of the ring. Due to the potential difference between the anode and the cathode, the electron beam of the cathode is accelerated to bombard the surface of the anode to generate field plasma and emit X-rays. This reflection target shooting method can obtain a smaller point source diameter and the maximum X-ray energy at an angle of 0°.

[0010] Preferably: the point light source filter comprises a molybdenum sheet with a thickness of 16 μm.

[0011] Preferably: the pulse power source comprises a Marx generator-pulse forming line-diode combination.

[0012] Preferably: the anode needle is 5mm long, the bottom diameter is 5mm, and the cone tip diameter is 0.2mm-0.4mm; the cathode outer diameter is 54mm, the inner diameter is 24mm, the inner diameter tip chamfer is 8-12°, the point light source filter is vertically arranged and the anode is opposite to the point light source filter, and the horizontal distance between the center position of the point light source filter and the center position of the cathode is 30mm-70mm; the pulse power source output voltage is 160kv, the voltage wave rise time is not more than 30ns, and the voltage wave pulse width is 90-115ns.

[0013] Preferably: the conical tungsten needle is 5mm long, the bottom diameter is 5mm, and the cone tip diameter is 0.2mm; the cathode outer diameter is 54mm, the inner diameter is 24mm, the inner diameter tip is chamfered at 10°, the point light source filter is vertically arranged and the anode is opposite to the point light source filter, and the horizontal distance between the center position of the point light source filter and the center position of the cathode is 50mm.

[0014] A method for producing a pulsed X-ray tube micro-focus point light source, comprising the pulsed X-ray tube micro-focus point light source device according to claims 1 to 7, and further comprising the following steps:

[0015] a) Fix the anode at the output of the pulse power device and the vacuum chamber, and keep it installed horizontally. The anode length is 5 cm, the bottom diameter is 5 mm, and the cone tip diameter is 0.2 mm.

[0016] b) The cathode has an outer diameter of 54mm, an inner diameter of 24mm, and a chamfer of 10° at the inner diameter tip. The horizontal distance between the cathode and the anode tip can be adjusted within 1-5mm. The point light source filter uses a 16μm thick molybdenum sheet and is installed at a 0° angle to the horizontal to ensure that the horizontal distance between the point light source filter and the cathode center is about 50mm. The horizontal distance can be adjusted within 10-20mm according to experimental needs.

[0017] c) Use molecular pump and mechanical pump to evacuate the vacuum chamber to make the vacuum degree Pa or higher.

[0018] The output voltage amplitude of the pulse power device is 160kV, the voltage wave rise time is 30ns, and the voltage wave pulse width is about 100ns, which discharges the vacuum cavity.

[0019] In summary, the present invention has the following beneficial effects compared with the prior art: 1. A cold cathode vacuum X-ray tube is adopted, a conical metal is used as an anode, and a circular steel sheet is used as a cathode, which is installed in a vacuum chamber to form a reflective target vacuum X-ray diode. The cold cathode has sharp corners or tips to promote the generation of field emission current. The design of the anode maximizes the intensity of the X-rays, while the emission area is as small as possible, thereby achieving a micro-focusing effect of the X-rays. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is an axonometric view of the first embodiment;

[0021] Figure 2 is a schematic diagram showing the position of the transmission rod in the first embodiment;

[0022] Figure 3 yes Figure 2 The middle is an enlarged view of part A showing the anode structure.

[0023] Figure numerals: 1. Pulse power source; 2. Vacuum chamber; 21. Transmission rod; 211. Base; 22. Mounting tube; 221. Point light source filter; 23. Moving table; 24. Generator tube; 25. Fixed table; 26. Fixed flange; 3. Anode; 4. Cathode; 41. Amplifier. DETAILED DESCRIPTION

[0024] Embodiment 1: A pulsed X-ray tube micro-focus point light source device and method, see Figure 1 and Figure 2 , including a pulse power source 1; the pulse power source 1 in this embodiment is composed of a Marx generator, a pulse forming line, and a diode, the pulse power source 1 outputs a voltage of 160kV, the voltage wave rise time is no more than 30ns, and the voltage wave pulse width is 90-115ns (the pulse power source 1 here is a prior art, so it will not be repeated). A vacuum cavity 2 is provided at the transmitting end of the pulse power source 1, and a horizontally arranged transmission rod 21 is fixedly connected between the vacuum cavity 2 and the pulse power source 1, and one end of the transmission rod 21 extends into the vacuum cavity 2.

[0025] See also Figure 2 and Figure 3The end of the transmission rod 21 extending into the vacuum chamber 2 is fixedly connected with a base 211, and the base 211 is fixedly connected with an anode 3. The anode 3 in this embodiment is a conical tungsten needle with a length of 5 mm, a bottom diameter of 5 mm, and a cone tip diameter of 0.2 mm. A fixed flange 26 coaxially arranged with the transmission rod 21 is fixedly connected inside the vacuum chamber 2, and a generator tube 24 coaxially arranged with the fixed flange 26 is bolted inside. The anode 3 and the base 211 are both located inside the generator tube 24, and the tip of the anode 3 is arranged toward the generator tube 24 and away from the end of the transmission rod 21. A fixed platform 25 is fixedly connected to the end of the generating tube 24 facing away from the transmission rod 21, and the fixed platform 25 is bolted to the movable platform 23, the side wall of the movable platform 23 abuts against the inner wall of the generating tube 24, and the end face of the movable platform 23 facing the anode 3 is fixedly connected to the cathode 4. In this embodiment, the cathode 4 is a circular steel sheet, and an enlarged portion 41 with a sharp edge is provided at the inner edge of the circular steel sheet, and the enlarged portion 41 extends from the inner edge of the cathode 4 toward the outer circle of the cathode 4, and forms a conical sidewall-shaped arc surface groove on the end face of the cathode 4 facing the anode 3. The cathode 4 has an outer diameter of 54 mm, an inner diameter of 24 mm, and a chamfer of 10° at the tip of the inner diameter. The end of the vacuum chamber 2 facing away from the transmission rod 21 is plugged with a mounting tube 22 coaxially arranged with the transmission rod 21, one end of the mounting tube 22 extends into the interior of the vacuum chamber 2, and a point light source filter 221 is fixedly connected to this end, and the transmission rod 21, the anode 3, the cathode 4 and the point light source filter 221 are coaxially arranged. The point light source filter 221 in this embodiment is a 16μm thick molybdenum sheet, the point light source filter 221 is vertically arranged and the anode 3 is directly opposite to the point light source filter 221, and the horizontal distance between the center position of the point light source filter 221 and the center position of the cathode 4 is 50mm.

[0026] The working principle of the pulse X-ray tube micro-focus point light source device and method when used is as follows: when the high-voltage positive pulse acts on the anode 3, the cathode 4 field strength is very high, and a ring-shaped electron beam will be generated in the cathode 4 ring due to field emission. After being accelerated by the electric field between the cathode and cathode 3, it bombards the anode 3 target to generate bremsstrahlung X-rays. This structure has the maximum X-ray transmission efficiency at an angle of 0 degrees. Through the fine processing of the anode 3 target cone tip, the size of the X-ray point source finally radiated can be in the order of hundreds of μm. Through the micro-focusing guidance of the cathode 4 and the anode 3, a small focal spot X-ray point source is generated after interacting with the filter. Through measurement, the size of the point source is in the order of hundreds of microns, completing the micro-focusing effect of the X-ray point source.

[0027] Embodiment 2: A method for producing a pulsed X-ray tube micro-focus point light source, comprising the following steps:

[0028] a) Fix the anode at the output of the pulse power device and the vacuum chamber, and keep it installed horizontally. The anode length is 5 cm, the bottom diameter is 5 mm, and the cone tip diameter is 0.2 mm.

[0029] b) The cathode has an outer diameter of 54mm, an inner diameter of 24mm, and a chamfer of 10° at the inner diameter tip. The horizontal distance between the cathode and the anode tip can be adjusted within 1-5mm. The point light source filter uses a 16μm thick molybdenum sheet and is installed at a 0° angle to the horizontal to ensure that the horizontal distance between the point light source filter and the cathode center is about 50mm. The horizontal distance can be adjusted within 10-20mm according to experimental needs.

[0030] c) Use molecular pump and mechanical pump to evacuate the vacuum chamber to make the vacuum degree Pa or higher. Among them: the output voltage amplitude of the pulse power device is 160kv, the voltage wave rise time is 30ns, the voltage wave pulse width is about 100ns, and the vacuum cavity is discharged

[0031] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A pulsed X-ray tube micro-focus point light source device, characterized in that: The invention comprises a pulse power source (1), a transmission rod (21), an anode (3), a cathode (4), a point light source filter (221) and a vacuum chamber (2); the transmission rod (21) connects the pulse power source (1) and the anode (3); the anode (3) comprises a conical rare earth metal material block; the cathode (4) comprises a ring-shaped steel sheet; the anode (3) is arranged horizontally with its tip facing the cathode (4); the cathode (4) is slidably connected to the inside of the vacuum chamber (2) along the length direction of the vacuum chamber (2); and the inside of the vacuum chamber (2) is slidably connected to the point light source filter (221) along its length direction; An enlarged portion (41) having a sharp edge is provided at the inner edge of the cathode (4); The point light source filter (221) comprises a molybdenum sheet with a thickness of 16 μm; The anode (3) has a needle length of 5 mm, a bottom diameter of 5 mm, and a cone tip diameter of 0.2 mm-0.4 mm; the cathode (4) has an outer diameter of 54 mm, an inner diameter of 24 mm, and an inner diameter tip chamfer of 8-12°; the point light source filter (221) is vertically arranged and the anode (3) is directly opposite to the point light source filter (221); the horizontal distance between the center position of the point light source filter (221) and the center position of the cathode (4) is 30 mm-70 mm; the pulse power source (1) has an output voltage of 160 kV, a voltage wave rise time of no more than 30 ns, and a voltage wave pulse width of 90-115 ns.

2. The pulse X-ray tube micro-focus point light source device according to claim 1, characterized in that: The anode (3) comprises a conical tungsten needle arranged in a conical shape toward the cathode (4).

3. The pulse X-ray tube micro-focus point light source device according to claim 1, characterized in that: The pulse power source (1) comprises a Marx generator-pulse forming line-diode combination.

4. The pulse X-ray tube micro-focus point light source device according to claim 1, characterized in that: The anode (3) is 5 mm long, has a bottom diameter of 5 mm, and a cone tip diameter of 0.2 mm; the cathode (4) has an outer diameter of 54 mm, an inner diameter of 24 mm, and a chamfer of 10° at the inner diameter tip; the point light source filter (221) is vertically arranged and the anode (3) is directly opposite to the point light source filter (221); and the horizontal distance between the center position of the point light source filter (221) and the center position of the cathode (4) is 50 mm.

5. A method for producing a pulsed X-ray tube micro-focused point light source, comprising the pulsed X-ray tube micro-focused point light source device according to claims 1 to 4, characterized in that: The following steps are also included: Fix the anode at the output of the pulse power device and the vacuum chamber, and keep it installed in a horizontal direction. The anode length is 5 cm, the bottom diameter is 5 mm, and the cone tip diameter is 0.2 mm. The cathode has an outer diameter of 54mm, an inner diameter of 24mm, and a chamfer of 10° at the inner diameter tip. The horizontal distance between the cathode and the anode tip can be adjusted within 1-5mm. The point light source filter uses a molybdenum sheet with a thickness of 16μm and is installed at an angle of 0° to the horizontal to ensure that the horizontal distance between the point light source filter and the cathode center is about 50mm. The horizontal distance can be adjusted within 10-20mm according to experimental needs. The vacuum chamber is evacuated by molecular pump and mechanical pump to make the vacuum degree ρ = 5 × 10 -3 Pa or higher; The output voltage amplitude of the pulse power device is 160kV, the voltage wave rise time is 30ns, and the voltage wave pulse width is about 100ns, which discharges the vacuum cavity.

Images