JPH04190598A - Magnetic field measuring method for electromagnet for particle accelerating device - Google Patents

Abstract

PURPOSE:To perform the magnetic field measurement of an electromagnet with high accuracy and reliability by seeking the displacement of the measured position based on the measured result of the magnetic field and correcting the measured result according to the displacement to seek the magnetic field strength at the real position. CONSTITUTION:A measuring device 13A is moved against a particle accelerating electromagnet 2 fixed, in a specified position, on a rack 11A and having a symmetrical shape, so as to measure magnetic fields at respective measurement positions of the electromagnet 2, and the real position of the electromagnet 2 is obtained based on the asymmetry of the measured values at least at both ends of the electromagnet 2 due to the measurement process. And, according to the displacement relative to the specified position during measuring the obtained real position, the measured value on measurement is corrected such that it is equal to the measured value on the electromagnet 2 provided at the real position. Thus, the process for seeking the real position of the electromagnet 2 and the process for correcting the measured value co-operate so as to cancel the magnetic field measurement error caused by the aforementioned error, even in a case where there has been an error in specifying the position of the electromagnet 2. Consequently, the magnetic field measurement with high reliability can be performed.

Description

[Detailed Description of the Invention] [Summary] The present invention relates to a method for measuring the magnetic field of a bending electromagnet, which is a component of a synchrotron synchrotron radiation generator, with the aim of enabling highly reliable magnetic field measurement. a step of moving a measuring device with respect to a particle accelerator electromagnet having a specified symmetrical shape to measure the magnetic field at each measurement position of the electromagnet, and at least both ends of the electromagnet according to the measuring step; The step of determining the true position of the electromagnet based on the asymmetry of the measured value of and a step of correcting the position to be the measured value on the electromagnet.

[Industrial application field]

The present invention relates to a method for measuring the magnetic field of a bending electromagnet that is a component of a synchrotron radiation generator.

Research is underway into X-ray exposure technology that will make it possible to increase the density of semiconductors.

As one of the light sources for exposure X-rays, there is a synchrotron radiation light generating apparatus 1 shown in FIG.

2 is a bending electromagnet (see Figure 12), 3 is a quadrupole electromagnet, 4 is a
is a high frequency acceleration cavity, 5 is a vacuum duct, and 6 is an injector. A beam line 7 guides X-rays (synchrotron radiation) generated at the bending electromagnet 2 to a wafer exposure section.

X-rays for exposing wafers need to be high in intensity and stable.

In order to extract such X-rays from the above device 1, it is necessary for a large number of charged particles to orbit stably, and for this purpose, the bending electromagnet 2 must be able to form a sufficiently uniform magnetic field distribution. Something is required.

In particular, for the bending electromagnet 2, in the coordinate system of FIG.
X=O, 5=O) and ΔB is B(X,5)-Bo) or 5X10-4 or less (within ±50 mm of X).

In addition, in the sense of the magnetic field strength that is effectively felt while a particle passes through the bending electromagnet 2 along the S axis, the integrated magnetic field strength distribution defined as fB (X, S) ds for the bending electromagnet is also Must be uniform.

As shown by the line ■ in Figure 13, within the range of ±50mm from X, from △ (X, 5) ds/JB (0, 5) ds or lX
It needs to be 10-3 or less.

In order to obtain such a highly accurate magnetic field distribution in the bending electromagnet 2, the magnetic pole 2c of the bending electromagnet 2 is required.

It is necessary to process the 2d portion with high precision on the μm order, and a method for measuring the magnetic field with high precision is also required.

For areas where the magnetic field strength changes rapidly, such as the magnetic pole end 2a of the electromagnet 2, the magnetic field strength changes by as much as 50 Gauss just by 0.5 mm from the measurement position.

In this respect as well, measurement of magnetic fields requires considerably high precision.

[Conventional technology]

Conventionally, magnetic field distribution has been measured using a measuring device 1o having the structure shown in FIG. 14 and through the steps shown in FIG. 15.

In FIG. 14, reference numeral 11 denotes a stand, on which the deflecting electromagnet 2, which is the object to be measured, is placed and fixed.

Reference numeral 12 denotes an x-y moving stage, which moves a measuring instrument 13 made of a Hall element.

As shown in FIGS. 12 and 16, the bending electromagnet 2 includes a piezo magnet 14- which is a permanent magnet with a pointed upper end.
1. 14-2 are provided at two locations.

The dimensions of each part of the electromagnet 2, the center position of the arc, etc. are determined by measurement in advance.

First, a first stage pilot magnet position measuring step '20 is performed.

In this step 20, the pilot magnet of the electromagnet 2 mounted and fixed on the pedestal 11 + 4-1. Using a micrometer or the like, determine the position of the pilot magnet 14-2 using a micrometer, etc., using the reference plane 16 of the electromagnet 2 as a reference, and as shown in FIG. Coordinates (X,, Y,) in the electromagnet X-Y coordinate system of 2.

Find (X2.Y2). The origin of the electromagnet X-Y coordinate system is the center of the arc of the electromagnet 2.

Next, a second stage pilot magnet position measuring step 21 is performed.

In step 21, the moving stage 12 is operated to move the measuring instrument I3 as shown by the dotted chain line in FIG.
Measuring device] 3, pilot magnet 14-L1
Detects the position of 4-2, pilot 14-], + 4-
Coordinates (X3.yl) in the measurement coordinate system, which is the x-y coordinate system of the moving stage 12 of No. 2.

Find (X2.y2).

Next, step 22 of finding a conversion formula for converting the measurement coordinate system into the electromagnet coordinate system is performed.

In this step 22, the four-dimensional simultaneous equations are solved to obtain coefficients A, B, C, and D.

As a result, a conversion formula for converting the measurement coordinate system to the electromagnetic coordinate system can be found.

Next, a magnetic field measurement step 23 is performed.

In this step 23, the movable stage is converted into the coefficients obtained in the above step 22 based on the conversion formula for both coordinate systems by substituting B, C, and D into the expressions (1) and (2). 12 is operated to sequentially move the measuring device 13 to a predetermined measurement position in the electromagnetic coordinate system, and the magnetic field is determined by 1ltl.

Next, step 24 of determining the magnetic field distribution is performed.

In this step, the strength of the magnetic field at each predetermined position obtained in step 23 is processed to determine the magnetic field distribution as shown by lines 30 to 34 in FIG. 17, for example.

Lines 30 are lines connecting positions where the magnetic field strength is 7 KG, and are hereinafter referred to as contour lines.

Similarly, line 31 is a contour line connecting the positions where the magnetic field strength is 7.5KG, and lines 32, 33, and 34 are contour lines connecting the positions where the magnetic field strength is 8K.
This is a contour line connecting the positions of G, 8.5 KC; and 9 KG.

In FIG. 17, reference numeral 39 indicates the outline (position) of the bending electromagnet 2 in the electromagnet coordinate system.

[Invention or problem to be solved]

In the second measurement method, in the step 20, the pilot magnet 14-1.14 is attached to the base surface 16 of the electromagnet 2.
-2 position is measured with high accuracy, and the coordinates in the measurement coordinate system of the pilot magnets 14-1 and 14-2 are accurately determined in step 21, and the magnetic field measurement is performed with high precision. This is a prerequisite.

By the way, since the electromagnet 2 is quite large, with a length of several meters, the measurement error in step 20 may become so large (1 mm or less) that it cannot be ignored in terms of magnetic field measurement accuracy.

Furthermore, in step 21, there is no guarantee that the measuring device 13 will exactly match the tips of the pilot magnets 14-1 and 112, and there may be a slight deviation.

Therefore, in the conventional measurement method, the measurement position is set at a position that is slightly different from the true position of the electromagnet 2.
There is a risk that the magnetic field measurement result may be mistaken for the true position of the magnetic field, and sufficient reliability cannot be guaranteed for the magnetic field measurement results.

Therefore, if each part of the bending electromagnet 2 is finely corrected based on the magnetic field measurement results, the completed bending electromagnet will be
In reality, the uniformity of the magnetic field distribution will be disturbed, and ultimately the intensity of the X-rays generated by the synchro I-ron radiation generator will be impaired.

An object of the present invention is to provide a method for measuring a magnetic field of an electromagnet for a particle accelerator, which enables highly reliable magnetic field measurement.

[Means to solve the problem]

As shown in FIG. 1, the present invention measures the magnetic field at each measurement position of the electromagnet by moving a measuring device relative to an electromagnet for a particle accelerator that is fixed to a pedestal, has a specified position, and has a symmetrical shape. a step 36 of determining the true position of the electromagnet based on the asymmetry of the measured values at least at both ends of the electromagnet according to the measuring step; i1! This configuration includes a step 37 of correcting the measured value at the time of the measurement so that it becomes the measured value of the electromagnet at the true position in accordance with the deviation from the position specified at a fixed time.

[Effect]

The step 36 of determining the true position of the electromagnet and the step 37 of correcting the measured value work together to eliminate magnetic field measurement errors caused by errors even if there is an error in identifying the position of the electromagnet. do.

〔Example〕

FIG. 2 shows a method for measuring the magnetic field of a bending electromagnet for a particle accelerator, which is an embodiment of the present invention.

Figure 3 shows the measuring device that measures the magnetic field, and Figure 4 shows the measuring device that measures the magnetic field.
The x-y moving stage is shown in the figure.

This measuring device 40 has substantially the same structure as the measuring device 10 shown in FIG. 14, and corresponding parts are designated by the same reference numerals with the suffix A added thereto.

41 is a stage for moving in the X direction, and 42 is a stage for moving in the Y direction.

In order to measure the magnetic field of the bending electromagnet 2, steps 20 to 24 are first performed as in the conventional method.

Description of steps 20 to 24 will be omitted.

Next, step 50 is performed to determine the true position of the electromagnet 2 in the electromagnet coordinate system based on the magnetic field distribution determined in step 24.

In this step 50, the ends 2a and 2b on both sides in the longitudinal direction of the electromagnet 2 are formed symmetrically with high precision, and the contour lines of the ends 2a and 2b are also parallel to the ends 2a and 2b. Assuming that it is supposed to be symmetrical,
Seeking true location.

17 and 5, 60-1 to 60-n are measurement positions along the right end 2a of the electromagnet 2 on the electromagnet coordinate system,
61-1 to 6N-n are measurement positions along the left end portion 2b.

Each measurement position 60-1 to 60-n, 61-1 to 61-
The distribution of the magnetic field strength measured at n is shown by the line 30 to 30 in FIG.
34.

This magnetic field distribution is asymmetric, and in FIG. 17, the magnetic field distribution on the right end 2a side is more protruding toward the inner or outer circumference, and the magnetic field distribution on the left end 2b side is , it can be seen whether it protrudes outward compared to the outer periphery or the inner periphery, contrary to the right side end 2a side.

Therefore, the electromagnet coordinate system obtained in steps 20 to 22 coincides with the true electromagnet coordinate system. The position should be slightly rotated clockwise with respect to the position 35 obtained by 22.

Next, the true position 62 of the electromagnet 2 in step 50 of 1.
We will explain the specific method of finding .

(1) First, obtain the rotation angle α.

■ In Figure 6, the measurement system -1 is exactly from the contour line on the -10° side.
Assuming that the magnetic field strength at point P on the S axis on the 0° line is 31,
Let Q be a point on the S axis on the +10° side that has the same strength as B1.

■ From the slope α of the contour line, assume that the center of deflection of the electromagnet system is located at point 0' in Figure 6. △θ1 from the position of point Q
is also known, and θ0. ρ. is also known. Therefore, the coordinates of points P and Q are (xp, yp) - (ρ., 0) (xo, yo) · (oo - cos (θ.

−Δθ1), ρ. It is found as sin (θ0−Δθ,)).

■ The formula for line segment zQ, β is 1! o ”'→y3'o = jan (θ.-α)・
(X-Xo) p, .→y = -tanα. (X-ρ0). Therefore, the coordinates of point O' can be found as follows.

(2) Next, obtain the origin movement (△X, △Y).

In reality, the magnetic field distribution seen in the radial direction perpendicular to the S-axis is not symmetrical about the S-axis due to the above-mentioned parallel movement (xo, yo). Therefore, the symmetry is adjusted by finely adjusting the position of 0' to be on the bisector (β.') of PQ. That is, in FIG. 6, ■-τ-ρ. How do you like it? 'Line segment up 0'
move.

As a result of the above, the rotation angle α and the origin movement (△X).

△Y) can be obtained.

Next, a step 51 of finding new coordinates of the electromagnet 2 is performed.

In this step 51, new coordinates (X', Y'') of the true position of the electromagnet 2 on the electromagnet coordinate system are determined by the following equation.

Next, a step 52 is performed in which the magnetic field strength on the new coordinate system is determined by interpolation from the observed measured values.

Specifically, this is carried out as shown in FIG. Assume that a measured value B2 is obtained at a certain position P2. This is P2 in the electromagnet coordinate system
That's not the position. Therefore, the position corresponding to 22 in the electromagnetic coordinate system is set to P by moving and rotating the origin. I ask. This is the new coordinate.

The magnetic field strength at Po is the surrounding Pl, P2. It is obtained by linear interpolation from P3°P4. That is, the location of each measurement position in the measurement coordinate system in the electromagnetic coordinate system is known from the measurement coordinate system, and the magnetic field strength at the new coordinates is determined by interpolation from surrounding measured values.

The above interpolation is performed for each measurement point, and then step 53 of determining the magnetic field distribution is performed.

In this step, processing is performed in the same manner as in step 24 described above.

As a result, the contour lines 30 to 34 in FIG. 17 are redrawn as shown by reference numerals 30A to 34A in FIG. 8.

The magnetic field distribution shown by these contour lines 30A to 34A is the one in which the measurement error in the above step 20.21 has been corrected,
It is more accurate and reliable than before.

Therefore, by finely correcting each part of the electromagnet 2 based on the magnetic field distribution obtained in Section 1, a bending electromagnet with a sufficiently uniform magnetic field distribution can be manufactured.

By using this deflection electromagnet, stable X-rays with higher intensity than conventional ones are extracted from the radiation generating apparatus shown in FIG.

FIG. 9(A) shows the measurement results of the magnetic field in the radial direction at the 10° position of the electromagnet 2, and FIG. 9(B) shows the results after correction.

Although the measurement results were asymmetrical, with the inner circumference being lower and the outer circumference being higher, as shown by line 70 in Fig. 9 (A), by making corrections, the line 71 in Fig. 9 (B) As shown, the inner and outer circumferential sides are symmetrical with respect to the center.

FIG. 10(A) shows the measurement results of the magnetic field in the radial direction at the +100 position of the electromagnet 2, and FIG. 10(B) shows the results after correction.

The measurement results were asymmetrical, with the outer circumference being lower and the inner circumference being higher, as shown by line 8o in Figure (A).
As a result of the correction, the inner circumferential side and the outer circumferential side are symmetrical with respect to the center, as shown by the line 81 in FIG. 5(B).

Because electromagnet 2 is manufactured with high precision, it was originally 11.
The strength of the magnetic field in the radial direction at the positions of 0° and +10° should be symmetrical about the center, and from the above results,
It can be seen that the above corrections are appropriate.

Note that the present invention is not limited to the above-mentioned embodiments, but can also be applied to measurement of the magnetic field of the quadrupole electromagnet 3.

〔Effect of the invention〕

As explained above, according to the present invention, the deviation of the measurement position is determined based on the measurement result of the magnetic field, and the measurement result is corrected according to this deviation to determine the magnetic field at the true position. Therefore, even if there is an error in the position of the electromagnet, the magnetic field of the electromagnet can be determined without this error.

Therefore, it is possible to measure the magnetic field of an electromagnet with higher precision and reliability than in the past.

Furthermore, by using this measurement result, it is possible to manufacture electromagnets for particle accelerators with highly accurate magnetic field distribution.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the principle configuration of the present invention. FIG. 2 is a diagram showing an example of the magnetic field measurement method of an electromagnet for a particle accelerator of the present invention. FIG. 3 is a diagram showing an apparatus used in the magnetic field measurement method of the present invention. Figure 4 is a diagram showing the movement stage in Figure 3, Figure 5 is a diagram showing the relationship between the position of the electromagnet on the electromagnet coordinate system and the true position of the electromagnet, and Figure 6 is the rotational movement of the electromagnet. Figure 7 is a diagram explaining the interpolation of measured values, Figure 8 is a diagram showing the magnetic field distribution after interpolation, and Figure 9 is the measurement result of the bending electromagnet's 10° position. Figure 1O is a diagram comparing the measurement result of the +10' position of the bending electromagnet and the result after correction.
Figure 1 shows the synchrotron radiation generator, Figure 12 shows the bending electromagnet in Figure 11, Figure 13 shows the integrated magnetic field strength distribution of the bending electromagnet in Figure 10, and Figure 14. 15 is a diagram showing the conventional magnetic field measurement method, FIG. 16 is a diagram showing the relationship between the electromagnet coordinate system and the measurement coordinate system, and FIG. 17 is the magnetic field distribution obtained by measurement. FIG. In the figure, 1 is a synchrotron radiation generator, 2 is a bending electromagnet, 13Δ is a measuring device,] 4-1. l 4-2 is a pilot magnet, 30-34
are contour lines based on the measurement results, 30△ to 34△ are redrawn contour lines, 35 is the magnetic field measurement process, 36 is the process of determining the true position of the electromagnet, 37 is the measurement value correction] process, 39 is the position of the electromagnet , 40 is a magnetic field measurement device, 41 is a stage moving in the X direction, 42 is a stage 50 for moving in the y direction, a process for finding the true position of the electromagnet, 51 is a process for finding new coordinates of the electromagnet, and 52 is a process for interpolating new coordinates. 53 is a step of determining magnetic field distribution; 60-1 to 60-n, 611 to 61n are measurement positions; 62
indicates the true position of the bending magnet = 19-. Patent applicant: Fujitsu Ltd.

Claims (1)

[Claims] A measuring instrument (
13A) to measure the magnetic field at each measurement position of the electromagnet (35, 20 to 23); and the asymmetry of the measured values at least at both ends (2a, 2b) of the electromagnet due to the measurement step. Steps (36, 50, 51) of determining the true position of the electromagnet based on the true position of the electromagnet; A step (37,
52) An electromagnet for a particle accelerator characterized by the following: