JP2001305293A - Open type gas target equipped with gas flow regulating mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an open type gas target equipped with gas flow regulating mechanism capable of independently regulating the gas quantity flowing into a beam chamber and the gas quantity supplied into the gas target. SOLUTION: One-side ends of auxiliary canals 11 and 12 are connected to the central gas feed part 3A of a gas target canal 3 through a flow regulating valve 10. The other end of the auxiliary canal 11 is connected to the part closer to a first beam chamber from the one-end side gas extraction part 3B1 of the gas, target canal 3, and the other end of the auxiliary canal 12 is connected to the part closer to a second beam chamber 2 fpm the other-end side gas extraction part 3C1 of the gas target canal. The gas flow regulating mechanism is formed of the flow regulating valve 10 and the first and second auxiliary canals 11 and 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to the treatment of cancer, PIX
The present invention relates to an open-type gas target used for various ion beam application devices for performing E, RBS, ion doping, and the like.

[0002]

2. Description of the Related Art In various ion beam applied devices for performing cancer treatment, PIXE, RBS, ion doping, and the like, an open gas target containing a gas for irradiating an ion beam may be provided.

[0003] For example, a low energy side acceleration tube, a charge converter, and a high energy side acceleration tube are provided. Negative ions accelerated by the low energy side acceleration tube are charge-converted into positive ions, and then the high energy side acceleration tube is used again. In a tandem accelerator that obtains a high energy ion beam by accelerating,
An open gas target in which a gas that collides with negative ions in order to strip electrons from negative ions is provided at a portion of the charge converter provided between the low energy side acceleration tube and the high energy acceleration tube.

Usually, this type of gas target is connected at one end and the other end to first and second beam chambers through which an ion beam passes, and the ion beam passing through the first beam chamber is introduced from one end side. A gas target canal, a gas supply source connected to a gas supply unit provided at an intermediate portion of the gas target canal via a gas regulator to supply gas into the gas target canal, and a gas target canal near one end of the gas target canal. At least one end gas recirculation means for sucking a part of the gas in the gas target canal by a pump from the provided one end gas extraction unit and returning the gas to the gas supply unit of the gas target canal; The gas in the gas target canal is extracted from the other end side gas extraction unit provided near the end. Part was sucked by a pump and a least one other end-gas recirculation means recirculates the gas supply portion of the gas target Canal.

[0005] In the case of a tandem accelerator, the low energy side acceleration tube corresponds to the first beam chamber, and the high energy side acceleration tube corresponds to the second beam chamber.

[0006]

In an ion beam apparatus equipped with a beam chamber such as an accelerating tube, if the degree of vacuum in the beam chamber is too high, discharge occurs inside the beam chamber. Therefore, to operate this kind of equipment stably, supply an appropriate amount of gas into the beam chamber,
It is necessary to keep the degree of vacuum in the beam chamber in an appropriate range.

When an open gas target is connected to the beam chamber, a part of the gas supplied into the gas target canal flows into the beam chamber. In this case, if the amount of gas flowing into the beam chamber from the gas target canal and the amount of gas flowing in the gas target canal can be separately adjusted, the gas pressure in the gas target canal and the vacuum in the beam chamber can be adjusted. The degree can be kept in an appropriate range.

However, in the conventional gas target, when the amount of gas supplied to the gas target canal is adjusted, the amount of gas flowing from the gas target canal into the beam chamber changes accordingly. Could not be maintained in an appropriate range.

Therefore, conventionally, a gas supply system for supplying gas into the beam chamber is provided in addition to the gas supply system for supplying gas into the gas target canal, so that the amount of gas supplied into the gas target canal can be reduced. It was necessary to be able to separately adjust the supply amount of gas into the beam chamber, and it was inevitable that the configuration of ion beam applied equipment became complicated.

An object of the present invention is to provide a structure in which a part of the gas supplied to the gas target canal is supplied to the beam chamber, and furthermore, the supply amount of the gas to the gas target canal and the gas supply to the beam chamber. To provide an open-type gas target with a gas flow rate adjusting mechanism capable of individually adjusting the supply amount of the gas.

[0011]

According to the present invention, one end and the other end are respectively connected to first and second beam chambers through which an ion beam passes, and the ion beam passing through the first beam chamber from one end side. A gas target canal to be introduced, a gas supply source connected to a gas supply unit provided at an intermediate portion of the gas target canal via a gas regulator to supply gas into the gas target canal, and a gas target canal near one end. At least one end-side gas recirculation means for sucking a part of the gas in the gas target canal by a pump from the one end side gas extraction unit provided to the gas target canal and returning the gas to the gas supply unit of the gas target canal; A part of the gas in the gas target canal is extracted from the other end side gas extraction unit provided near the other end. Those related to the open-type gas targets and at least one other end gas recirculation means for recirculating the gas supply portion of the gas target Canard by suction by pump.

In the present invention, a first auxiliary canal and a second auxiliary canal are connected in parallel to a first beam chamber side portion and a second beam chamber side portion of a gas target canal, respectively, to adjust a flow rate. The valve allows the conductance of each of the first auxiliary canal and the second auxiliary canal to be adjusted.

More specifically, the first auxiliary canal has one end connected to a gas supply section of the gas target canal via a flow rate control valve, and the other end connected to a gas extraction section on one end side of the gas target canal. Is also provided in a state of being connected to a portion near the first beam chamber. Also the second
The auxiliary canal is connected at one end to the gas supply unit of the gas target canal via the flow control valve, and the other end is closer to the second beam chamber than the gas extraction unit at the other end of the gas target canal. Provided in a connected state.

A gas flow control mechanism is constituted by the flow control valve and the first and second auxiliary canals. By adjusting the flow control valve, the amount of gas flowing into the first and second auxiliary canals is reduced. Adjust so that the amount of gas supplied into the gas target canal can be adjusted.

In the above-mentioned gas target, if the flow control valve is throttled while a fixed amount of gas is supplied from the gas supply source into the gas target canal, the amount of gas flowing into the auxiliary canal decreases, The amount of gas supplied into the target canal increases. At this time, the amount of gas supplied from the auxiliary canal into the beam chamber decreases, but the amount of gas supplied from the gas target canal into the beam chamber increases by the amount of gas supplied from the auxiliary canal into the beam chamber. To do
The total amount of gas supplied from the gas target canal and the auxiliary canal into the beam chamber is the same as before the flow control valve is throttled.

When the flow control valve is opened, the amount of gas flowing into the auxiliary canal increases, and the amount of gas supplied into the gas target canal decreases. At this time, the amount of gas supplied from the auxiliary canal into the beam chamber increases, but the amount of gas supplied from the gas target canal into the beam chamber increases as the amount of gas supplied from the auxiliary canal to the beam chamber increases. Since the amount is reduced by the amount, the total amount of gas supplied from the gas target canal and the auxiliary canal into the beam chamber is the same as before opening the flow control valve.

The amount of gas supplied into the beam chamber is determined by the amount of gas supplied from the gas supply source into the gas target canal, and is not affected by the amount of gas flowing through the gas target canal.

Therefore, with the above configuration, the amount of gas supplied into the first and second beam chambers can be adjusted by the amount of gas supplied from the gas supply source into the gas target canal. Also, by keeping the amount of gas supplied from the gas supply source into the gas target canal constant and adjusting the flow control valve, without changing the amount of gas supplied into the beam chamber,
The amount of gas supplied into the gas target chamber can be adjusted.

Therefore, according to the present invention, a part of the gas supplied into the gas target canal is supplied to the beam chamber side without separately providing a gas supply system for supplying the gas into the beam chamber. In addition, the supply amount of gas into the gas target canal and the supply amount of gas into the beam chamber can be individually adjusted. Both the degree of vacuum in the beam chamber can be adjusted to an optimum state.

In the above configuration, the flow control valve is provided in common for the first auxiliary canal and the second auxiliary canal, but the first and second auxiliary canals are respectively provided with the first and second auxiliary canals. And a second flow control valve is provided, one end of the first auxiliary canal is connected to the gas supply unit of the gas target canal via the first flow control valve, and one end of the second auxiliary canal is connected to the second canal. The gas target canal may be connected to a gas supply unit via a flow rate adjustment valve.

In the present invention, a first vacuum gauge for measuring the degree of vacuum in the gas supply section of the gas target canal, and a plurality of first vacuum gauges for measuring the degree of vacuum at a plurality of locations along the longitudinal direction of the gas target canal, respectively. Two vacuum gauges,
Gas pressure calculating means for calculating the gas pressure in the gas supply unit of the gas target canal from the degree of vacuum measured by the first vacuum gauge, and a plurality of second vacuum gauges are provided from the gas pressure calculated by the gas pressure calculating means. A vacuum degree distribution estimating means for estimating the degree of vacuum at the determined location, and comparing the degree of vacuum measured by each of the plurality of second vacuum gauges with the degree of vacuum estimated by the degree of vacuum distribution estimating means, the gas target Determining means for determining whether or not the degree of vacuum distribution in the canal is normal; and setting the degree of vacuum in the gas supply unit of the gas target canal in a state where the degree of vacuum is determined to be normal by the determining means. The gas supply unit of the gas target canal in a state where the flow rate of the gas flowing through the flow rate control valve is decreased when the pressure is higher than Further it is preferable to provide a valve control means for controlling the flow rate control valve such that a vacuum degree increases the flow rate of the gas flowing through the flow rate adjusting valve is lower than the set value of.

With this configuration, it is possible to automatically control the gas pressure and the degree of vacuum in the gas target canal. In addition, since it is possible to determine whether the degree of vacuum distribution in the gas target canal is normal or abnormal, it is possible to prevent the operation from being performed while the degree of vacuum distribution is abnormal.

In the above configuration, the gas pressure in the gas supply unit (the maximum gas pressure in the gas target canal) is calculated from the degree of vacuum in the gas supply unit of the gas target canal. The gas pressure in the gas supply unit of the gas target canal may be calculated from the gas flow rate.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of the structure of an open gas target used in a tandem accelerator as an example of an open gas target according to the present invention. In the figure, reference numerals 1 and 2 denote tubular first and second beam chambers (accelerating tubes in this example) arranged with their axes aligned, and reference numeral 3 denotes a tubular beam chamber arranged between the beam chambers 1 and 2. The gas target is Canal. Gas Target Canal 3
The beam chambers 1 and 2 are arranged so that their axes are aligned with each other, and one end is connected to the first beam chamber 1 and the other end is connected to the second beam chamber 2.

A gas supply unit 3A is provided at the center of the gas target canal 3. A gas cylinder 5 as a gas supply source is connected to the gas supply unit 3A via a regulator 4, and a gas return header 6 is connected to the gas supply unit 3A. One end of the auxiliary canal connection pipe 7 is connected. At one end of the gas target canal 3, first and second one-side gas extraction units 3B1 and 3B2 are provided. At the other end of the gas target canal 3, first and second other-side gas extraction units 3C1 are provided. And 3C2 are provided. First end side gas extraction unit 3B1
And the first other end side gas extraction unit 3C1 is provided symmetrically with respect to the gas supply unit 3A, and these gas extraction units 3B1 and 3C1
Are connected to a first end-side pump 8B1 and a first other-end side pump 8C1 for sucking and extracting a part of the gas in the gas target canal, respectively. The discharge port of the pump 8B1 is connected to the header 6 through a gas return pipe 9B1, and the discharge port of the pump 8C1 is connected to the header 6 through a gas return pipe 9C1.
It is connected to the.

Similarly, the second one-side gas extraction section 3B2 and the second other-side gas extraction section 3C2 are provided symmetrically with respect to the gas supply section 3A, and the gas extraction sections 3B2 and 3C2 are provided with gas respectively. A second one-side pump 8B2 and a second other-side pump 8C2 for sucking and extracting a part of the gas in the target canal are connected. The outlet of the pump 8B2 is connected to the header 6 through a gas return pipe 9B2.
The outlet of C2 is connected to the header 6 through a gas return pipe 9C2.

In this example, the pump 8B1 and the return pipe 9B1
The first end-side gas recirculation means G11 is constituted by the pump and the header 6, and the second end-side gas recirculation means G12 is constituted by the pump 8B2, the return pipe 9B2 and the header 6. The pump 8C1, the return pipe 9C1 and the header 6 make the first
The other end side gas recirculation means G21 is constituted, and the pump 8C2, the return pipe 9C2 and the header 6 constitute the second other end side gas recirculation means G22.

As the pumps 8B1, 8B2, 8C1 and 8C2, turbo molecular pumps are used.

The other end of the auxiliary canal connecting pipe 7 is connected to the first tubular auxiliary canal 1 through a flow control valve 10.
One end of one and one end of the second auxiliary canal 12 are connected. The other end of the first auxiliary canal 11 is connected to a portion closer to the first beam chamber 1 than the gas extraction unit 3B1 on one end side of the gas target canal 3, and the other end of the second auxiliary canal 12 is connected to the gas target canal 11. The other end 3 is connected to a portion closer to the second beam chamber 2 than the gas extraction unit 3C1.

The gas flow control mechanism is constituted by the flow control valve 10 and the auxiliary canals 11 and 12.

A first vacuum gauge 13 for measuring the degree of vacuum inside the gas supply unit 3A set at an intermediate portion of the gas target canal 3 is attached to the gas supply unit 3A.
Connection point between the other end of the gas target canal 3 and the intermediate point between the gas extraction units 3B1 and 3B2, gas extraction units 3C1 and 3C2
And four second vacuum gauges 14 for measuring the degree of vacuum inside each of the intermediate point between them and the connection point between the other end of the auxiliary canal 12 and the gas target canal 3 are attached.

Each of the vacuum gauges 13 and 14 outputs an electrical detection signal indicating the degree of vacuum measured by the vacuum gauge. The detection signals output from these vacuum gauges are output to a control unit 15 having a microcomputer. Has been entered. The control device 15 processes signals given from the vacuum gauges 13 and 14 by an algorithm described later, and sends a control signal to the operation unit 10a of the flow rate adjustment valve 10 so as to keep the gas pressure in the gas target canal 3 at a set value. give.

In the example shown in FIG. 1, the gas target functioning as a charge converter is constituted by the gas target canal 3, the gas recirculation means G11, G12, G21 and G22, the flow regulating valve 10 and the auxiliary canals 11 and 12. Have been.

Although not shown, a vacuum pump for evacuating the inside of the beam chambers 1 and 2 is provided, and the inside of the beam chambers 1 and 2 is evacuated by the vacuum pump. The inside of the auxiliary canals 11 and 12 is evacuated.

In the gas target shown in FIG.
Since the gas is supplied from the gas cylinder 5 to the central portion of the gas target canal 3, the gas pressure in the gas target canal 3 becomes maximum at the central portion, and the gas pressure inside the gas target canal 3 increases toward one end and the other end. Is getting lower. The pressure distribution in the gas target canal 3 shown in FIG. 1 is schematically shown in FIG. 2, points a to i shown on the horizontal axis correspond to points a to i shown in FIG. 1, respectively. Points a and b are points corresponding to the edge on the beam chamber 1 side and the edge on the opposite side of the beam chamber 1 of the gas extraction port provided in the first end side gas extraction unit 3B1, respectively, and points c and d.
The points correspond to the edge on the beam chamber 1 side and the edge on the opposite side of the beam chamber 1 of the gas extraction port provided in the second one-side gas extraction unit 3B2. The point e is the center point of the gas supply section 3A of the gas target canal, and the points f and g are located on the opposite side of the beam chamber 2 of the gas extraction port provided in the second other end gas extraction section 3C2. This is a point corresponding to the edge and the edge on the beam chamber 2 side. Further, points h and i correspond to the edge of the gas extraction port provided in the first other end side gas extraction unit 3C1 on the side opposite to the beam chamber 2 and the edge on the side of the beam chamber 2, respectively.

The example shown in FIG. 1 shows a charge converter portion of a tandem accelerator. In the tandem accelerator, the beam chamber 1 is a low energy side acceleration tube, and the beam chamber 2 is a high energy side acceleration tube. Tube. In this case, the ends of the beam chambers 1 and 2 on the gas target side and the gas target canal 3 are electrically connected to each other so as to have the same potential, and the ends (not shown) of the beam chambers 1 and 2 are grounded. . Then, a high voltage is applied between the ground potential section and the gas target canal 3, and a negative ion beam is introduced into the beam chamber (acceleration tube) 1 from an end (not shown) of the chamber 1. The negative ion beam is accelerated while passing through the ion chamber 1 and is introduced into the gas target canal 3. Negative ions introduced into the canal 3 are converted into positive ions because they collide with gas molecules in the canal 3 and lose their electrons. The positive ions are supplied to beam chamber 2 (accelerator)
Then, it is accelerated again and irradiated to a target (not shown).

In order to properly perform charge conversion in this type of gas target, it is necessary to keep the gas pressure in the gas target canal 3 (particularly, the maximum pressure in FIG. 2) at a set value. In order to prevent discharge from occurring in the beam chambers 1 and 2, it is necessary to supply an appropriate amount of gas into the beam chambers 1 and 2. In the gas target shown in FIG. 1, the gas pressure in the gas target canal 3 can be adjusted by adjusting the flow rate adjustment valve 10, and the amount of gas supplied from the gas cylinder 5 into the gas target canal 3 is adjusted. By doing so, the amount of gas supplied into the beam chambers 1 and 2 can be adjusted.

In the above gas target, when the flow control valve 10 is squeezed while a constant amount of gas is being supplied from the gas cylinder 5 into the gas target canal 3, the amount of gas flowing into the auxiliary canals 11 and 12 is reduced. Decreased,
The amount of gas supplied into the gas target canal 3 increases. At this time, the amount of gas supplied from the auxiliary canal 11 into the beam chamber 1 and the amount of gas supplied from the auxiliary canal 12 into the beam chamber 2 decrease.
Since the amount of gas supplied from the gas target canal 3 to the beam chambers 1 and 2 increases by the amount of gas supplied from the auxiliary canals 11 and 12 into the beam chambers 1 and 2, respectively, the gas targets canal 3 and The total amount of gas supplied from the auxiliary canal 11 into the beam chamber 1 and the total amount of gas supplied from the gas target canal 3 and the auxiliary canal 12 into the beam chamber 2 are the same as before the flow control valve 10 is throttled.

When the flow control valve 10 is opened, the amount of gas flowing into the auxiliary canals 11 and 12 increases, and the amount of gas supplied into the gas target canals 3 decreases. At this time, the amount of gas supplied into the beam chambers 1 and 2 from the auxiliary canals 11 and 12 respectively increases. And 12 decrease by the increase in the amount of gas supplied to the beam chambers 1 and 2. Therefore, the total amount of gas supplied from the gas target canal 3 and the auxiliary canal 11 into the beam chamber 1 and the total amount of gas supplied from the gas target canal 3 and the auxiliary canal 12 to the beam chamber 2 open the flow control valve. Same as before.

The amount of gas supplied to each of the beam chambers 1 and 2 is determined by the amount of gas supplied from the gas cylinder 5 to the gas target canal.
It is not affected by the amount of gas flowing in the gas target Canal 3.

Therefore, with the above configuration, the amount of gas supplied into the first and second beam chambers 1 and 2 can be adjusted by the amount of gas supplied from the gas cylinder 5 into the gas target canal 3. Can be. By adjusting the flow control valve 7 while keeping the amount of gas supplied from the gas cylinder 5 into the gas target canal 3 constant, the gas target chamber 3 can be supplied without changing the amount of gas supplied into the beam chambers 1 and 2. The amount of gas supplied into the inside can be adjusted.

Therefore, according to the present invention, a part of the gas supplied into the gas target canal 3 is supplied to the beam chambers 1 and 2 without separately providing a gas supply system for supplying the gas into the beam chambers 1 and 2. And the gas target canal 3
The amount of gas supplied into the gas target and the amount of gas supplied into the beam chambers 1 and 2 can be individually adjusted, and the vacuum distribution and beam chamber in the gas target canal 3 can be adjusted without complicating the configuration. Both the degree of vacuum in 1 and 2 can be adjusted to an optimal state.

FIG. 3 is a flowchart showing an algorithm of a program executed by the microcomputer of the control device 15 in order to automatically adjust the gas pressure in the gas target canal 3.

When the algorithm shown in FIG. 3 is followed, the degree of vacuum Ve at point e detected by the vacuum gauge 13 is read in step 1 and then, in step 2, each part other than point e is detected by the plurality of vacuum gauges 14. Is read. Next, in step 3, the gas pressure Pe at point e is calculated from the degree of vacuum Ve at point e using a pressure calculation table.
Then, using the pressure / vacuum conversion table prepared in advance,
The degree of vacuum of each part when the gas pressure at point e is Pe (vacuum gauge 14
The estimated value Vn 'of the degree of vacuum of each part provided with is calculated. Next, in step 5, the estimated value V of the degree of vacuum of each part is obtained.
By comparing n ′ with the actual vacuum degree Vn of each part measured by the vacuum gauge 14, it is determined whether or not the estimated value Vn ′ of the vacuum degree and the actual vacuum degree Vn match within an error range. I do.

When the gas flow in the gas target is normal, the estimated value Vn 'of the degree of vacuum and the actual degree of vacuum Vn match within a predetermined error range.

If it is determined in step 5 that the estimated value of the degree of vacuum of each part and the actual degree of vacuum are within the error range, it is determined that the degree of vacuum distribution in the gas target canal 3 is normal. In step 6, the gas pressure Pe at the center e of the gas target canal 3 calculated in step 4 is compared with a set value. As a result of comparing the gas pressure Pe with the set value, if the gas pressure Pe is higher than the set value, the process proceeds to step 7 to increase the flow rate of the gas flowing through the flow control valve 10, and returns to step 1.

If it is determined in step 6 that the gas pressure Pe matches the set value within the error range, the process proceeds to step 8, leaving the flow control valve 10 as it is, and returns to step 1.

When it is determined in step 6 that the gas pressure Pe is lower than the set value, the routine proceeds to step 9 where the flow regulating valve 10 is throttled, and the routine returns to step 1.

If it is determined in step 5 that the estimated value of the degree of vacuum of each part does not match the actual degree of vacuum, the process proceeds to step 10 to output an abnormality detection signal.
When the abnormality detection signal is output, a warning display such as lighting of a red lamp is performed, and measures such as stopping the operation of the device using the gas target are taken.

In the example shown in FIG.
A gas pressure calculating means for calculating the gas pressure in the gas supply unit 3A of the gas target canal 3 from the degree of vacuum measured by the first vacuum gauge 13 is realized.

In step 4, the plurality of second vacuum gauges 14 are calculated from the gas pressure Pe calculated by the gas pressure calculating means.
Is realized, a degree-of-vacuum distribution estimating means for estimating the degree of vacuum at the location where is provided.

Further, in step 5, the degree of vacuum measured by the plurality of second vacuum gauges 14 is compared with the degree of vacuum estimated by the degree-of-vacuum distribution estimating means to determine the degree of vacuum distribution in the gas target canal. Is realized, which determines whether or not is normal.

In steps 6 to 9, when the gas pressure in the gas supply section 3A of the gas target canal 3 is higher than the set value in a state where the vacuum degree distribution is determined to be normal by the determination means, the flow rate is determined. When the gas pressure in the gas supply unit 3A of the gas target canal 3 is lower than the set value while the flow rate of the gas flowing through the adjustment valve is reduced and the determination unit determines that the degree of vacuum distribution is normal, Valve control means for controlling the flow control valve so as to increase the flow rate of the gas flowing through the flow control valve 10 is realized.

Step 10 implements an abnormality detection signal generating means for generating an abnormality detection signal indicating that the gas flow in the gas target is abnormal.

If the control device 15 having the above functions is provided, the flow control valve 10 is automatically adjusted to automatically maintain the gas pressure in the gas target canal 3 at an appropriate value. Can be.

In the above example, the gas target canal 3
The gas pressure in the gas supply unit (the maximum gas pressure in the gas target canal) Pe is calculated from the degree of vacuum in the gas supply unit 3A (the degree of vacuum measured by the vacuum gauge 13). A sensor for measuring the flow rate of the gas flowing through 10 may be provided, and the gas pressure in the gas supply unit 3A of the gas target canal may be calculated from the flow rate of the gas detected by the sensor. This calculation can also be performed by a known method of performing an interpolation operation on data read from a gas flow rate / gas pressure conversion table that gives a relationship between the gas flow rate flowing through the flow rate adjustment valve 10 and the gas pressure Pe.

In the above example, one flow control valve 10 is provided in common for the first auxiliary canal 11 and the second auxiliary canal 12, but as shown in FIG. First and second flow control valves 10A and 10B are provided for the canal 11 and the second auxiliary canal 12, respectively, so that one end of the first auxiliary canal 11 is connected to the first auxiliary canal 11.
Connected to the gas supply unit 3A of the gas target canal 3 via the flow control valve 10A of
2 may be connected to the gas supply unit 3A of the gas target canal via the second flow control valve 10B.

In the above example, the gas target canal 3
The first and second one end gas recirculation means G11 and G12 are provided at one end of the gas target, and the first end is provided at the other end of the gas target canal 3.
And the second other end gas recirculation means G21 and G22 are provided. At least one of these gas recirculation means may be provided on one end side and the other end side of the gas target canal, respectively. One is not limited to the above example.

In the above example, a gas target used as a charge converter in a tandem accelerator is taken as an example. However, the present invention is not limited to this, and an open type gas target provided in an ion beam application device is used. The present invention can be widely applied to (a target in which an ion beam is irradiated is a gas and the gas is contained in a canal having both ends opened at a predetermined internal pressure).

[0060]

As described above, according to the present invention, the first and second auxiliary canals are connected in parallel to one end and the other end of the gas target canal, respectively. Since a flow rate adjusting valve for adjusting the flow rate of the gas flowing to the second auxiliary canal side was provided, and the gas pressure in the gas target canal was adjusted by adjusting the flow rate adjusting valve,
The amount of gas supplied into the first and second beam chambers can be set according to the amount of gas supplied from the gas supply source into the gas target canal. In addition, by adjusting the flow control valve while keeping the flow rate of the gas supplied from the gas supply source into the gas target canal constant, the amount of gas supplied into the first and second beam chambers is not changed. The amount of gas supplied into the gas target chamber can be adjusted.

Therefore, according to the present invention, a part of the gas supplied into the gas target canal is supplied to the beam chamber without providing a gas supply system for supplying the gas into the beam chamber. In addition, the supply amount of gas into the gas target canal and the supply amount of gas into the beam chamber can be individually adjusted. Both the degree of vacuum in the beam chamber can be adjusted to an optimum state.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a configuration example of a gas target according to the present invention.

FIG. 2 is a diagram schematically showing a pressure distribution in a gas target canal of the gas target of FIG. 1;

FIG. 3 is a flowchart illustrating an example of an algorithm of a process performed by a control device provided in the gas target of FIG. 1;

FIG. 4 is a configuration diagram showing another configuration example of the gas target according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... 1st beam chamber, 2 ... 2nd beam chamber, 3 ... gas target canal, 3A ... gas supply part, 3B1, 3B2 ... one end side gas extraction part, 3C1, 3C2 ... other end side gas extraction part, 4 ... Regulator, 5 ... Gas cylinder, 1
0, 10A, 10B: flow control valve, 11: first auxiliary canal, 12: second auxiliary canal, 13: first vacuum gauge, 14: second vacuum gauge, 15: control device.

Claims (4)

[Claims] 1. A gas target canal having one end and the other end connected to first and second beam chambers for passing an ion beam, respectively, and an ion beam passing through the first beam chamber being introduced from the one end side. A gas supply source connected to a gas supply unit provided at an intermediate portion of the gas target canal via a gas regulator to supply gas into the gas target canal, and a gas supply source provided near one end of the gas target canal. At least one end gas recirculation means for sucking a part of the gas in the gas target canal from the one end gas extraction unit by a pump and returning the gas to the gas supply unit of the gas target canal; The gas in the gas target canal is extracted from the other end side gas extraction unit provided near the other end. An open-type gas target comprising at least one other gas recirculation means for sucking a part of the gas by the pump and returning the gas to the gas supply unit of the gas target canal; A first auxiliary canal having one end connected via an adjustment valve and having the other end connected to a portion of the gas target canal closer to the first beam chamber than the one end side gas extraction unit; and One end is connected to the gas supply unit via the flow control valve, and the other end is connected to a portion closer to the second beam chamber than the other end side gas extraction unit of the gas target canal. Gas flow adjustment by the flow control valve and the first and second auxiliary canals. Open type gas target with the gas flow rate adjusting mechanism configured is configured. 2. A gas target canal having one end and the other end connected to first and second beam chambers for passing an ion beam, respectively, and an ion beam passing through the first beam chamber being introduced from the one end side. A gas supply source connected to a gas supply unit provided at an intermediate portion of the gas target canal via a gas regulator to supply gas into the gas target canal, and a gas supply source provided near one end of the gas target canal. At least one end gas recirculation means for sucking a part of gas in the gas target canal from the one end gas extraction unit by a pump and returning the gas to the gas supply unit of the gas target canal; The gas in the gas target canal is extracted from the other end side gas extraction unit provided near the other end. An open-type gas target having at least one other end-side gas recirculation means for sucking a part of the gas by the pump and recirculating the gas to the gas supply unit of the gas target canal; One end is connected via a flow control valve of the first gas target canal, and the first gas extraction unit of the gas target canal is connected to the first end.
The other end of which is connected to the portion near the beam chamber of
One end of the gas target canal is connected to the gas supply section of the gas target canal via a second flow control valve, and the second end of the gas target canal is connected to the second end of the gas target canal.
The other end of which is connected to the portion near the beam chamber of
And the first and second flow control valves and the first and second canal.
An open type gas target with a gas flow rate adjustment mechanism in which a gas flow rate adjustment mechanism is constituted by the auxiliary canal. 3. A first vacuum gauge for measuring the degree of vacuum in the gas supply section of the gas target canal, and a plurality of second gauges for measuring the degree of vacuum at a plurality of locations along a longitudinal direction of the gas target canal. Vacuum gauge and the first
Gas pressure calculating means for calculating the gas pressure in the gas supply unit of the gas target canal from the degree of vacuum measured by the vacuum gauge, and the plurality of second vacuum gauges based on the gas pressure calculated by the gas pressure calculating means. A vacuum degree distribution estimating means for estimating the degree of vacuum at a location provided with, and comparing the degree of vacuum measured by the plurality of second vacuum gauges with the degree of vacuum estimated by the vacuum degree distribution estimating means. Determining means for determining whether or not the degree of vacuum distribution in the gas target canal is normal, and the gas of the gas target canal in a state where the degree of vacuum is determined to be normal by the determining means. When the degree of vacuum in the supply unit is higher than a set value, the flow rate of the gas flowing through the flow rate control valve is reduced, and the determination unit determines that the degree of vacuum distribution is normal. Valve control means for controlling the flow rate control valve so as to increase the flow rate of gas flowing through the flow rate control valve when the degree of vacuum in the gas supply unit of the gas target canal is lower than the set value in a state where The open gas target with a gas flow rate adjusting mechanism according to claim 1 or 2, further comprising: 4. A plurality of vacuum gauges for measuring a degree of vacuum at a plurality of locations along a longitudinal direction of the gas target canal, a flow sensor for detecting a flow rate of gas flowing through the flow control valve, and the flow sensor. Gas pressure calculating means for calculating the gas pressure in the gas supply unit of the gas target canal from the detected gas flow rate, and a place where the plurality of vacuum gauges are provided from the gas pressure calculated by the gas pressure calculating means Vacuum degree distribution estimating means for estimating the degree of vacuum, and comparing the degree of vacuum measured by the plurality of vacuum gauges with the degree of vacuum estimated by the vacuum degree distribution estimating means, the gas target canal Determining means for determining whether the vacuum degree distribution is normal,
When the degree of vacuum is determined to be normal by the determination means and the degree of vacuum in the gas supply unit of the gas target canal is higher than a set value, the flow rate of the gas flowing through the flow rate control valve is reduced. The flow rate of the gas flowing through the flow rate control valve when the degree of vacuum in the gas supply unit of the gas target canal is lower than the set value in a state where the degree of vacuum distribution is determined to be normal by the determination means. The open type gas target with a gas flow rate adjusting mechanism according to claim 1, further comprising valve control means for controlling the flow rate adjusting valve so as to increase the flow rate.