RU185071U1 - DEVICE FOR FOCUSING BEAMS OF ACCELERATED CHARGED PARTICLES ON THE IRRADIATED OBJECT - Google Patents

Abstract

The proposed utility model relates to the technique of focusing beams of accelerated charged particles on the irradiated object and can be used for technological processes in which beams of accelerated charged particles are used, in particular, when conducting element-wise analysis of materials. The technical result of the utility model is the ability to quickly install the irradiated object as much as possible close to the end of the capillary without damaging it. The technical result of the utility model is ensured by the fact that in the device for foci beams of accelerated charged particles on an irradiated object placed in an evacuated volume and containing a truncated cone-shaped dielectric capillary fixed in a metal casing, the cone narrowing direction coinciding with the direction of propagation of charged particles, it is new that it is equipped with a contact sensor of extreme position, formed by two electrodes, one of which is mounted on the housing with the ability to move along the axis of the capillary and is made in the form of a metal rod, and ntaktnym electrode integral with the irradiated object. 1 s.p. f-ly, 1 ill.

Description

The proposed utility model relates to the technique of focusing beams of accelerated charged particles on the irradiated object and can be used for technological processes in which beams of accelerated charged particles are used, in particular, when conducting elementwise analysis of materials.

A device for focusing beams of accelerated charged particles is known (utility model RU No. 113859, “Device for focusing beams of accelerated charged particles”, published 02.27.2012, Bull. No. 6), placed in an evacuated volume and containing a dielectric capillary in the form of a truncated cone, fixed in a metal case, located between the source of accelerated charged particles and the irradiated object, and the direction of narrowing of the cone coincides with the direction of propagation of the charged particles.

The known device has the disadvantage associated with the lack of operational control of the distance between the capillary and the irradiated object. When conducting research, installation of the object at a minimum distance from the edge of the capillary is required. The smaller the distance from the object to the edge of the capillary will be established, the smaller the beam size on the irradiated object, and the more information about the structure of the material will be obtained. However, in the absence of control of the axial clearance between the object and the edge of the capillary, it is possible that the object touches the capillary end. In this case, the fragile, often made of glass, capillary end may break off. To avoid breaking the capillary, it is necessary to control the axial clearance between the object and the edge of the capillary.

The proposed utility model solves the technical problem of providing a high-performance analysis of the structure of the studied material.

The technical result of the utility model is the ability to quickly install the irradiated object as close as possible to the end of the capillary without damaging it.

The technical result of the utility model is ensured by the fact that in a device for focusing beams of accelerated charged particles placed in an evacuated volume and containing a truncated cone-shaped dielectric capillary fixed in a metal casing, the cone narrowing direction coincides with the direction of propagation of charged particles, new is that it is equipped with a contact sensor of the extreme position formed by two electrodes, one of which is mounted on the housing with the possibility of moving in eh axis of the capillary and is formed as a metal rod, and the contact electrode, is rigidly connected with the irradiated object.

In addition, a conductive layer may be applied to the dielectric capillary.

The contact sensor of the extreme position acts as a closing switch in the circuit of the optical signaling device (light bulb, LED) or the sound signaling device (sound frequency generator) and serves to indicate that the irradiated object has reached its working axial position relative to the end of the capillary. When the object reaches its working position, the metal rod of the sensor closes to the contact electrode, and the signaling device generates a light or sound signal, perceived by the operator as a command to stop the axial movement of the irradiated object.

Before work, the sensor is pre-configured, which includes the installation of the irradiated object at the required axial distance relative to the end of the capillary using an optical measuring microscope. After that, the rod moves towards the contact electrode until they are mutually shorted and is fixed in this position. Now, when the irradiated object is removed from the end of the capillary (for example, to replace one irradiated object with another), the installation of the object back to its working position takes the minimum time, since it consists in bringing the irradiated object to the end of the capillary until the contact sensor closes, which is much simpler and requires several times less time than installing with a microscope. In this case, the rigid connection of the contact electrode with the irradiated object provides a constant relative position of the electrode relative to the object and, accordingly, accurate positioning of the object relative to the end of the capillary.

The application of a conductive layer to a dielectric capillary aims to neutralize the electric charge that accumulates on the dielectric capillary when focusing accelerated charged particles. The conductive layer is applied using conductive glue (for example, Contactol glue) or vacuum deposition of silver or another metal.

The design of the proposed technical solution is schematically shown in Fig., Where:

1 - evacuated volume;

2 - source of accelerated charged particles;

3 - metal case;

4 - conductive layer;

5 - dielectric capillary;

6 - irradiated object;

7 - contact electrode;

8 - metal rod.

A device for focusing charged particle beams on an irradiated object is located in an evacuated volume 1 and contains a dielectric capillary 5 fixed in a metal case 3 and located between the source of accelerated charged particles 2 and the irradiated object 6. A metal rod 8 is mounted on the metal case 3, which has the possibility of axial displacement relative to the axis of the capillary 5. Opposite the rod 8 is a contact electrode 7, rigidly connected to the irradiated object 6, a mandrel connecting them or being 6. Land part of the object surface electrode 7 and the irradiated object 6 facing the end of the capillary 5 may act either to each other or in the same plane.

A device for focusing beams as follows.

Before work, the irradiated object 6 is pre-installed using appropriate means (stepper motor, micrometric screws) at the required axial distance relative to the end of the capillary 5 using an optical measuring microscope. After that, the rod 8 extends towards the contact electrode 7 until the contact sensor closes, which is accompanied by an optical or sound signal and means the working positioning of the object 6 relative to the capillary 5. The location of the surfaces of the electrode 7 and the irradiated object 6 from the side of the capillary 5 in one plane, the preset is to ensure the protrusion of the edge of the rod 8 relative to the end of the capillary 5 at a given distance.

After installing the irradiated object, a beam of accelerated protons from source 2 was introduced into the inner cavity of the capillary 5 in the direction of narrowing of the cone parallel to its axis. In the capillary 5, the beam was focused, which was then directed to the irradiated object.

To estimate the size of the spot of protons passing through the capillary, a Gafchromic EBT3 dosimetric film was selected, which was attached in front of the end of the Femtotip dielectric capillary. Before installation in the chamber, the edge of the rod 8 protruded from the end of the capillary 5 at a distance of 100 μm, which corresponded to the distance between the capillary 5 and the dosimetric film when the contact sensor was triggered. At the same time, a lamp illuminated, signaling a circuit closure. Then, the sample was irradiated with 4 MeV protons for 1 second at an average beam current of 1.5–10 ^-12 A. It was found that the beam diameter at a distance of 100 μm from the end of the capillary is 31 μm.

Tests of the inventive device showed that when using a contact sensor it is much easier to set the distance to the irradiated object, while the output end of the capillary is completely protected from damage.

The technical result, which consists in the ability to quickly install the irradiated object as close to the end of the capillary without damage, is fully implemented. The device is simple and cheap to manufacture.

Claims (2)

1. Device for focusing beams of accelerated charged particles on the irradiated object, placed in a vacuum volume and containing a dielectric capillary in the form of a truncated cone, mounted in a metal case, and the direction of narrowing of the cone coincides with the direction of propagation of the charged particles, characterized in that it is equipped with a contact sensor extreme position formed by two electrodes, one of which is mounted on the housing with the ability to move along the axis of the capillary and is made in the form of metal rod, and a contact electrode rigidly connected to the irradiated object. 2. The device according to claim 1, characterized in that a conductive layer is applied to the dielectric capillary.

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