PLC-based BNCT high duty cycle ECR ion source efficient beam output system and method

Abstract

The present invention relates to the field of BNCT technology, and in particular to a BNCT high duty cycle ECR ion source efficient beam emission system and method based on PLC. The ECR ion source includes a microwave generation and microwave transmission feeding system, a discharge chamber, an extraction system, a vacuum system, a beam measurement system, a power supply system, a high-voltage system and a control system. The specific generation mechanism is: the microwave power generated by the magnetron is transmitted through a waveguide and coupled to the discharge chamber, and a microwave electric field is formed in the discharge chamber. Under the action and constraint of the axial static magnetic field, some electrons perform Larmor cyclotron motion in the magnetic field. When the cyclotron frequency of the electrons is equal to the microwave frequency, some electrons will be heated by cyclotron resonance and ionize the working gas to generate high-temperature plasma. After the delay treatment is performed using the method steps described in the present invention, the difficulty of beam emission of the ECR ion source is greatly reduced, and beam emission can be completed with one key, and the method described in the present invention is a sequential step, which can be implemented by PLC or host computer program, and is easy to integrate into the original control system.

Description

Technical Field

[0001] The invention relates to the technical field of BNCT, and in particular to a PLC-based BNCT high duty cycle ECR ion source efficient beam output system and method. Background Art

[0002] Boron neutron capture therapy (BNCT) is a radiotherapy that uses neutrons to react with boron in tumors to destroy cancer cells. It is mainly composed of proton accelerators, neutron generation targets, boron-containing drugs, treatment software, and dose measurement subsystems.

[0003] BNCT uses ECR ion source as a proton generator. Ion source is a device that ionizes neutral atoms or molecules and draws out ion beams. It is widely used in accelerators, high-energy physics, ion implanters, semiconductors, and cancer treatment. As a proton generator, ECR ion source first injects hydrogen, loads microwave power, and loads a confining magnetic field.

[0004] Ionization generates plasma, and then a high voltage of 75kV is applied to extract the protons in the plasma, and then further accelerate them to the required energy to complete the target shooting. At the moment of applying high voltage, the extraction optical path will change with the high voltage and will not be on the correct optical path, so some hydrogen protons will hit the suppression electrode and knock out electrons. Under the action of high voltage, the electrons will accelerate in the reverse direction to form a local short circuit, and the high voltage cannot be applied. Summary of the invention

[0005] In response to the above-mentioned problem that electrons will be reversely accelerated to form a local short circuit under the action of high voltage, and the high voltage cannot be applied, the present invention aims to provide a PLC-based BNCT high duty cycle ECR ion source efficient beam output system and method to solve the problems of local short circuit and inability to apply high voltage.

[0006] The technical solution adopted by the present invention to solve the technical problem is: a BNCT high duty cycle ECR ion source efficient beam output system based on PLC, wherein the ECR ion source includes a microwave generation and microwave transmission feeding system, a discharge chamber, an extraction system, a vacuum system, a beam measurement system, a power supply system, a high voltage system and a control system. The ion source extraction system adopts a three-electrode structure, including a plasma electrode, a suppression electrode and a ground electrode. The plasma electrode is at a positive high potential, the suppression electrode is at a negative potential, and the ground electrode is at a ground potential.

[0007] The plasma electrode is 70-80 kV.

[0008] The suppression electrode is -3--1kv.

[0009] The method includes completing the following steps based on PLC control:

[0010] S1, turn off the microwave power output: turn off the microwave power output of the ECR ion source;

[0011] S2, turn off the suppression power output: after a delay, turn off the suppression power output;

[0012] S3, turn off the acceleration power output: after a delay, turn off the acceleration power output;

[0013] S4, modify the timing pulse width: modify the duty cycle and set the timing pulse width;

[0014] S5, turn on the suppression power output: after a delay, turn on the suppression power output;

[0015] S6, turn on the acceleration power output: after a delay, turn on the acceleration power output;

[0016] S7, turn on the microwave power output: after a delay, turn on the microwave power output.

[0017] The PLC-based BNCT high-duty-cycle ECR ion source efficient beam emission method can achieve efficient beam emission through sequential operation under narrow pulses.

[0018] The delay time in S2 is 150-250 milliseconds.

[0019] The delay time in S3 is 150-250 milliseconds.

[0020] The delay time in S5 is 150-250 milliseconds.

[0021] The delay time in S6 is 350-450 milliseconds.

[0022] The delay time in S7 is 550-650 milliseconds.

[0023] The beneficial effects of the present invention are as follows: after adopting the system and method described in the present invention, the difficulty of ECR ​​ion source beam emission is greatly reduced, and beam emission can be completed with one click. Moreover, the method described in the present invention is a sequential step, which can be implemented through PLC or host computer program and is easy to integrate into the original control system. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the ECR source extraction structure of the present invention.

[0025] Figure 2 It is a schematic diagram of the one-key beam-emitting operation method of the present invention.

[0026] Description of the accompanying drawings: 1-plasma generator, 2-plasma electrode, 3-suppression electrode, 4-ground electrode. DETAILED DESCRIPTION

[0027] The specific implementation of the present invention is described in detail below with reference to the accompanying drawings:

[0028] like Figure 1-2 , a BNCT high duty cycle ECR ion source efficient beam output system and method based on PLC, used to solve the problems of local short circuit and inability to apply high voltage; wherein the extraction structure of the ECR ion source includes a plasma electrode, a suppression electrode, and a ground electrode. The plasma electrode is at a positive high potential, the suppression electrode is at a negative potential, and the ground electrode is at a ground potential; the plasma electrode 2 of the arc chamber plasma generator 1 is at a positive high potential, the plasma electrode 2 is 0-80kv, the suppression electrode 3 is at a negative potential, the suppression electrode 3 is -3--1kv, and the ground electrode 4 is at a ground potential; as shown in the ECR source extraction structure diagram, the plasma electrode 2 is at a positive high potential, preferably 75kv; the suppression electrode 3 is preferably -2.2kv, and the ground electrode 4 is at a ground potential. Due to the negative potential of the suppression electrode 3, the free electrons generated by the protons hitting the ground electrode 4 after the suppression electrode 3 cannot be reversely injected back into the ion source.

[0029] The BNCT high duty cycle ECR ion source efficient beam emission method based on PLC, the method described in the present invention is a sequential step, which can be realized by PLC or host computer program, and is easy to integrate into the original control system, and is mainly realized by the following steps:

[0030] S1, turn off microwave power output: turn off the microwave power output of the ECR ion source.

[0031] S2, turn off the suppression power output: after a delay of 150-250 milliseconds, preferably after 200 milliseconds, turn off the suppression power output.

[0032] S3, turn off the acceleration power output: turn off the acceleration power output after a delay of 150-250 milliseconds, preferably after 200 milliseconds.

[0033] S4, modify the timing pulse width: modify the duty cycle and set the timing pulse width; the timing pulse width can be manually input through the device operation interface and modified in the program background. This value is usually input in advance and read directly when used.

[0034] S5, turn on the suppression power output: delay 150-250 milliseconds, preferably 200 milliseconds, and then turn on the suppression power output.

[0035] S6, turning on the acceleration power output: after a delay of 350-450 milliseconds, preferably 400 milliseconds, the acceleration power output is then turned on.

[0036] S7, turn on the microwave power output: after a delay of 550-650 milliseconds, preferably 600 milliseconds, turn on the microwave power output to achieve one-key beam emission.

[0037] The present invention discloses a sequential step of a PLC-based BNCT high-duty-cycle ECR ion source efficient beam emission method, which can be realized by a PLC or a host computer program and is easy to be integrated into an original control system. The difficulty of beam emission of the ECR ion source is greatly reduced, and the beam emission of the ion source can be completed with one key. The present invention mainly requires protection of the operation steps of the one-key beam emission and the delay time of each step, thereby avoiding the problems of frequent beam emission failures due to manual operation, especially beam emission difficulties at high duty cycles, requiring repeated operations, or gradually increasing the duty cycle after beam emission at low duty cycles. After adopting this method, the difficulty of beam emission is greatly reduced, and the beam emission of the ion source can be completed with one key.

[0038] The above description is only a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Technical personnel in this industry can make some deformation and modifications under the inspiration of this technical solution. Any modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A PLC-based BNCT high duty cycle ECR ion source efficient beam output method, characterized by: The ECR ion source includes a microwave generation and microwave transmission feeding system, a discharge chamber, an extraction system, a vacuum system, a beam measurement system, a power supply system, a high voltage system and a control system; the ion source extraction system adopts a three-electrode structure, including a plasma electrode, a suppression electrode, and a ground electrode; the plasma electrode is at a positive high potential, the suppression electrode is at a negative potential, and the ground electrode is at a ground potential; the method includes completing the following steps based on PLC control: S1, turn off the microwave power output: turn off the microwave power output of the ECR ion source; S2, turn off the suppression power output: after a delay, turn off the suppression power output; S3, turn off the acceleration power output: after a delay, turn off the acceleration power output; S4, modify the timing pulse width: modify the duty cycle and set the timing pulse width; S5, turn on the suppression power output: after a delay, turn on the suppression power output; S6, turn on the acceleration power output: after a delay, turn on the acceleration power output; S7, turn on the microwave power output: after a delay, turn on the microwave power output; The method described achieves efficient beam generation through sequential operation under narrow pulses; The plasma electrode is 70-80kv; The suppression electrode is -3--1kv; The delay time in S2 is 150-250 milliseconds; The delay time in S3 is 150-250 milliseconds; The delay time in S5 is 150-250 milliseconds; The delay time in S6 is 350-450 milliseconds; The delay time in S7 is 550-650 milliseconds.

Images