JPH0524480B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a steering coil, and more specifically, to a steering coil for beam deflection used in a beam transport system for high-energy beams. It is.

[Prior Art] Figures 13 and 14 show conventional steering coils, including racetrack-shaped coils 1a to 1d.
Vacuum duct 2 for passing high energy beam
The coils are arranged surrounding the opposing 1a
1c, 1b, and 1d sandwich the vacuum duct 2 in pairs, and generate a magnetic field for vertically and horizontally deflecting the beam passing through the vacuum duct 2.

[Problems to be solved by the invention] In the conventional steering coil as described above,
Due to the arrangement of the coils, there was a problem that the uniformity of the magnetic field was poor.

The present invention aims to solve these problems, and aims to obtain a steering coil with good magnetic field uniformity.

[Means for Solving the Problems] A steering coil according to the present invention includes a pair of racetrack-shaped coils arranged across a vacuum duct through which a high-energy beam passes. The ratio ζ between the coil length and the coil width is -0.11α+0.74≦ζ≦−0.102α+0.777 when 1≦α<1.5 and when 1.5≦α<2 −0.05α+0.65≦ζ≦−0.048α+0.696 When 2≦α<3, −0.02α+0.59≦ζ≦−0.016α+0.632 When 3≦α<5, −0.002α+0.536≦ζ≦ -0.002α+0.59 When 5≦α, it is in the range of 0.526≦ζ≦0.58.

[Operation] In the present invention, a highly uniform magnetic field is generated by specifying the arrangement and dimensions of the coil.

[Embodiment] FIGS. 1 and 2 show an embodiment of the present invention.
1a to 1d are racetrack-shaped coils;
g is the coil spacing, w is the coil width, and L is the coil length (length of the straight portion). 2 is a vacuum duct.

Here, the coil length L is relatively long (L/w=
α≧1) In a race track coil,
The generated magnetic field is mainly determined by the straight section of the coil.

If the straight part of the coil is modeled as shown in FIGS. 3 and 4, and the magnetic permeability is μ ₀ and the coil current is _i , the strength of the magnetic field at point A is determined as shown below.
In addition, in the figure, 3 indicates a calculated linear current.

B _Y =μ ₀ i/π×{w/2−x/(g/2 ² +(w/2−
x) ² L/√L ² +g ² +(w-2x) ² +w/2+x/(g
/2 ² + (w/2+x) ² L/√L ² +g ² + (w+2x) ² }
Here, let g=ζw x=βw/2 L=αw and find the uniformity for the central magnetic field B _YO =B _Y (x=0).

f=B _Y /B _YO −1 =1+ζ ² /2√α ² ζ ² +1 ×{1−β/ζ ² +(1−β) ² 1/√α ² +ζ ² +(1
−β) ² +1+β/ζ ² +(1+β) ² 1/√α ² +ζ ² +(1+
β) ² }-1 By calculating this for each parameter α and β, the magnetic field uniformity f can be found. The calculation results are shown in FIGS. 6 to 12. These figures show the ratio ζ between the coil spacing g and the coil width w, with the ratio α between the coil length L and the coil width w and the ratio β between the position x of point A and half the coil width w/2 as parameters. This is a graph of the magnetic field uniformity f with respect to the magnetic field uniformity f.

Here, if the magnetic field uniformity f is about -0.005 to 0.005, it can be said that the performance is sufficient compared to the conventional steering coil, and the coil width w is usually β = 0.3. The design is such that the magnetic field uniformity f is sufficient.

From these conditions, first of all, when α=1, β=
It is sufficient to set ζ=0.63 to 0.675 so that the graph of 0.3 falls within the range of f=-0.005 to 0.005. Similarly, α=
When 1.5, ζ=0.575~0.624, When α=2, ζ=0.55~0.6, When α=3, ζ=0.53~
0.584, when α=5, ζ=0.526~0.58, α=
When α=10, ζ=0.526 to 0.58, and when α=10000, ζ=0.526 to 0.58.

When each value of ζ obtained in the above manner is plotted against α and made into a line graph, the result is as shown in FIG. Depending on the value of α, the value of ζ is set above the solid line and below the broken line.

Also, ζ is less than 1 (coil spacing g is coil width w
Therefore, in order to arrange two sets of coils that are perpendicular to each other at the same location, the coils 1a to 1d must be combined in a parallel grid.

As described above, the uniformity of the magnetic field is improved,
This is especially advantageous in the case of a pulse steering device in which it is not possible to arrange the magnetic poles of the iron core to improve the uniformity of the magnetic field.

[Effect of the invention] As is clear from the above description, the invention has the following effects:
It is equipped with a pair of racetrack-shaped coils placed across a vacuum duct through which a high-energy beam passes, and this coil has a ratio of the coil spacing to the coil width to the ratio α of the coil length to the coil width. Since ζ is set within the range shown in FIG. 5, a steering coil with high magnetic field uniformity can be obtained.

[Brief explanation of drawings]

1 to 12 show an embodiment of the present invention, FIGS. 1 and 2 are a front sectional view and a side view, FIGS. 3 and 4 are a front view and a side view of a magnetic field calculation model, FIG. 5 is a graph summarizing the calculation results of magnetic field uniformity, and FIGS. 6 to 12 are graphs showing the calculation results of magnetic field uniformity. FIGS. 13 and 14 are a front sectional view and a side view of a conventional steering coil. 1a to 1d...Coil, 2...Vacuum duct. In each figure, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] 1. A pair of racetrack-shaped coils placed across a vacuum duct through which a high-energy beam passes, and the ratio ζ of the coil spacing to the coil width is Letting α be the ratio of length to coil width, when 1≦α<1.5 -0.11α+0.74≦ζ≦-0.102α+0.777 When 1.5≦α<2, -0.05α+0.65≦ζ≦-0.048 α+0.696 When 2≦α<3 -0.02α+0.59≦ζ≦−0.016α+0.632 When 3≦α<5 –0.002α+0.536≦ζ≦−0.002α+0.59 When 5≦α Steering coil in the range 0.526≦ζ≦0.58. 2. The steering coil according to claim 1, characterized in that two pairs of coils that are orthogonal to each other are combined in a cross-shaped structure.