JPH04155800A - Device for displaying region where beam adjustment parameter can be set - Google Patents

Abstract

PURPOSE:To easily adjust a beam in the optimum state by providing a means for calculating parameter region on the basis of a preset approximate expression and its display means, and making a parameter setting region a region where beam adjustment parameter can be set. CONSTITUTION:When a accelerating conditions of a beam (such as kinds of accelerated particles, energy, number of electric charges, etc.) are decided, an approximate expression presenting an orbital radius just before a phase slit is preliminarily been obtained off-line, and at the time of actual adjustment a parameter setting region is calculated on the basis of the approximate expression, and it is shown on a display 13 in real time as a region where beam adjustment parameter can be set. Thus, the duty of an operater is to make micro-adjustment of an adjustment parameter by means of a setting means such as a rotary encoder 14, a mouse 15, etc., within the shown feasible region, so that a beam can be adjusted in the optimum state.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides a method for displaying the settable area of the adjustment parameter when setting the adjustment parameter for adjusting the state of the beam in the central region of the cyclotron. Related to display devices.

(Prior art) Generally, in a cyclotron, there is an input system that makes the incident beam enter the acceleration surface, and a magnetic field that generates a magnetic field perpendicular to the acceleration surface in order to cause the incident beam to move in an orbit around the acceleration surface, that is, the central region. A magnet system, a high frequency system that generates an accelerating electric field for accelerating the incident beam, and an extraction system that extracts the accelerated beam are provided.

In such a cyclotron, beam currents are observed in each prefecture and adjustment parameters are adjusted in each prefecture based on these beam currents in order to extract the optimum accelerated beam. Adjustment parameters include electromagnets and magnetic lenses.

Factors such as high frequency equipment can be cited.

(Problems to be Solved by the Invention) In the conventional cyclotron, adjustment parameters for each prefecture are set in advance as initial setting values.

After that, the beam current is observed and each adjustment parameter is changed based on the change in the beam current, so that the adjustment parameter that maximizes the beam current is set.

However, when changing the adjustment parameters as in the past, there is a problem in that the operator must finely adjust each adjustment parameter through trial and error, making adjustment of the adjustment parameters extremely troublesome.

An object of the present invention is to provide a display device that can display a region in which adjustment parameters can be set to maximize beam current when adjusting adjustment parameters.

(Means for Solving the Problems) According to the present invention, an entrance system is provided that guides an incident beam to an acceleration surface, and the entrance system includes a lens group having a plurality of magnetic lenses and a rear end side of the lens group. The inflector is used in a cyclotron that accelerates the beam incident from the input system while interlocking the orbit in the central region and takes out the accelerated beam, and the adjustment parameter in the central region is a means for inputting data necessary for calculating a settable area of the area, a setting means for setting adjustment parameters for adjusting the beam trajectory of the central area, and an approximation of the beam trajectory of the central area that has been created in advance. comprising means for calculating a parameter setting area based on a formula, and display means for displaying the parameter setting area,
There is obtained a beam adjustment parameter settable area display device characterized in that the parameter setting area is the beam adjustment parameter settable area.

(Function) In the present invention, when the beam acceleration conditions (type of accelerated particles, energy, number of charges, etc.) are determined, an approximate expression expressing the orbital radius immediately before the phase slit is obtained off-line, and during actual adjustment. A parameter setting area is calculated based on the approximate expression, and this parameter setting area is displayed as a beam adjustment parameter setting possible area.

Therefore, the operator only has to fine-tune the adjustment parameters within this displayed beam adjustment parameter setting area using a setting means such as a rotary encoder or a mouse.
As a result, the beam can be easily brought into the optimum state.

(Example) The present invention will be explained below with reference to Examples.

Referring to FIG. 1, in general, a cyclotron has an input system 1
, a magnet system 2 having a main electromagnet with a north pole 2N and a south pole 2S, a high frequency system 3, and an extraction system 4 having a deflector.The entrance system 1 includes a lens group having a plurality of magnetic lens units L and this lens. and an inflector disposed on the rear end side of the group.

The incident beam is made incident on the acceleration surface on the day electrode 5 by the incidence system 1, and is caused to undergo orbital motion by the magnetic field directly applied to the acceleration surface from the magnet system 2. On the other hand, a high frequency accelerating electric field is applied to the incident beam by the high frequency system 3,
This accelerates the incident beam. Then, the accelerated beam is extracted from the extraction system 4. At this time, the beam current is detected for each system by a beam current detection sensor.

Referring to FIG. 2, the settable area display device according to the present invention includes a beam condition input device 11 for inputting data necessary for calculating the settable area of adjustment parameters in the central region of the cyclotron. Arithmetic unit (hereinafter referred to as CPU)
12. and a display 13. Beam conditions include the type of accelerated particles, energy, number of charges, etc. The CPU 12 includes a rotary encoder 14 whose values can be easily changed as means for setting adjustment parameters.
Alternatively, a mouse 15 or the like is connected.

Also for CPUI 2. Magnetic field database storing magnetic field data and electric field data in the central region of the cyclotron 16. An electric field database 17 is connected.

Figure 3 shows an example of displaying the structure of the central region of the cyclotron and the beam trajectory, showing the inflector exit 21, blur 22
．． 1st. A second phase slit 23° 24 is shown.

Two phase slits 23.2 from the inflector outlet 21
The section up to 4 is called a central area block.

The beam guided to the acceleration plane by the inflector undergoes a curved motion in three-dimensional space under the deflection force of the central magnetic field and the acceleration force of the day electrode.

And the motion of the particles in the central region is.

The following string mortar d P/dt −q (E + le XB) (
1). (However, P is the momentum of the particle, q is the charge of the particle, E is the electric field, V is the particle velocity, and B is the magnetic field.) Solving the above differential equation at every minute time Δ, the displacement of V・Δt can be calculated. By sequentially accumulating the values, the trajectory of the particle under a certain initial condition can be determined.

For example, choose three parameters for adjusting the center region: day voltage, magnetic field in the center region, and beam incidence phase, and change the settable range of other adjustment parameters in real time when any of these is changed. It is an object of the present invention to calculate and display. This is the blur 22. shown in FIG. 1st. This is because the beam needs to pass through without hitting the second phase slits 23, 24, etc.

The three types of beam trajectories shown in Figure 3 have a day voltage of 4
RK is the particle motion when set to 0.50.60kV.
(Runge-Kutta-Gill) method.

For the reasons mentioned above, the day voltage, the magnetic field in the central region.

By finely adjusting the beam incidence phase, the beam can be adjusted to the first position without being blocked by the blur 22. It is necessary to search for conditions for passing through the phase slits 23 and 24 of w42 in real time.

Here, although the RK method described above can relatively accurately obtain the overall image of the beam trajectory, it requires a long calculation time due to sequential calculation. (For example, VAX3100
It takes about 4 seconds to trace one particle. )For this reason,
It is not realistic to search for a settable area in real time during adjustment based on the trajectory calculation method using the RK method.

Therefore, an approximate model of the trajectory is created and a settable area is calculated based on it. What determines the acceptance of the central region is the position of the two phase slits r@l+
r,2 and gap dalda2.

The orbit radius rl+r2 of the particle at the position of the phase slit is rat-ds+/2<r,<r,,+cL+/2
(2)' @2 d a2/ 2 < r , 2 <
If r 12+ d 12/2 (3) is satisfied, the particle will pass through the central region. In other words, to calculate the settable area + rl + r
2 and Day voltage V, initial phase φ, central magnetic field increment m +rl-fl(v, φ, m) and r2-
It is sufficient to know f2 (V, φ, m). This function f,
Since the order and coefficients of f2 are unknown, an approximate expression is derived using the well-known GMDH method without determining the function form in advance.

The input data x-(v, φ, ml is used by calculating the orbital radius in several sets of setting values by the RK method. Also, a linear equation is used as the basic function.

z-a, +a, x, +a2 x2+a3 x, 2+a
4 X22+a5x, X2 (4) In this device, beam acceleration conditions (particle type, energy, etc.)
When the equation is decided, an approximate formula is obtained off-line, and when making adjustments, 'l+'2 is approximated online to ensure real-time performance of one display.

Next, in order to calculate the settable region of the adjustment parameter, we use a function w(v
, φ, m) as W-V/work2+W2' (5) Wl
-maX (l r, -rail-d, /2.
IW2 ”'tmaX (I r2 rs21 d
s2/2. (Define this as the objective function and formulate it as eight nonlinear minimization problems. If we solve the region where w −0 is 1° using the method proposed (Japanese Patent Application No. 165528/1999), we get This is the settable region. An example of this is shown in Figure 4. Figure 4 (a) shows an example of the display between the incident beam phase and the 2-day voltage, and Figure 4 (b) shows the central magnetic field. An example of display between and day voltage is shown.

The current setting value is indicated by a cross cursor.

Note that the incident beam has distribution in the radial direction (Δr) and angular direction (Δpr) with respect to the central orbit 12 of the inflector, but here, one particle (Δr−0, Δ
The settable region was determined by representing the incident beam as 0 (pr-0).

The operator operates the low encoder 14 and the mouse 15 while monitoring the displays shown in FIGS. 4(a) and 4(b).
Finely adjust the day voltage, central magnetic field, and beam incident phase using the following steps to find the optimal adjustment parameters for the beam to pass through the two phase slits. Note that, depending on the required quality of the extracted beam, it is also possible to adjust the position 1 width of the phase slit that determines the acceptance of this central region block.

(Effects of the Invention) As explained above, in the present invention, since the adjustment parameter settable area is displayed on the display device in real time, the operator can check whether the beam adjustment parameters can be set within the displayed beam adjustment parameter settable area or not. It is only necessary to finely adjust the alignment parameters, and as a result, the beam can be easily brought to an optimum state.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a cyclotron to which the present invention is applied;
Fig. 2 is a block diagram schematically showing an embodiment of the beam adjustment parameter setting area display device according to the present invention, Fig. 3 is a diagram illustrating the structure of the central area of the cyclotron and the beam trajectory, and Fig. 4 is a diagram of the display. FIG. 2 is a diagram two-dimensionally showing an adjustment parameter setting area on the device. 11... Beam condition input device, 12... Arithmetic device (
CPU), 13...Display, 14...Lori encoder, 15...Mouse, 21...Inflator output 0.22...Blur, 23.24...1st degree 2nd phase slit . Fig. 2 Fig. 3 Himimura Irimura I α phase

Claims (1)

[Claims] 1. An entrance system that guides an incident beam to an accelerating surface, the entrance system comprising a lens group having a plurality of magnetic lenses and an inflector disposed on the rear end side of the lens group. This system is used in a cyclotron that accelerates a beam incident from the input system while orbiting in the central region and extracts the accelerated beam, and is used to calculate the settable region of adjustment parameters in the central region. a means for inputting necessary data, a setting means for setting adjustment parameters for adjusting the beam trajectory of the central region, and a parameter setting area based on an approximation formula for the beam trajectory of the central region created in advance. A beam adjustment parameter settable area, comprising: a calculation means; and a display means for displaying the parameter setting area, and the parameter setting area is the beam adjustment parameter settable area. Display device. 2. The beam adjustment parameter settable area display device according to claim 1, wherein the adjustment parameters are a Dee voltage, an initial phase, and a central magnetic field. .