Automatically operated accelerator using obtained operating patterns

A beam transfer system has a bending magnet, a quadrupole magnet for converging or diverging a beam, and a beam current monitor. The controller of an accelerator body for the beam transfer system has a beam current measuring apparatus, a quantity-of-control measuring apparatus for measuring a quantity of control such as an exciting current of a bending magnet, a quantity-of-control determining apparatus for determining the quantity of control of each component, a trigger generating apparatus for generating various trigger signals, and a main controller for determining the quantity of control and the control timing of every component.

TECHNICAL FIELD 
The present invention relates to an accelerator, particularly to an 
accelerator which is automatically operated and which can preferably be 
used for industries or medical treatment. The present invention also 
relates to an operating method for such an accelerator. 
BACKGROUND ART 
As described in "Electronic `Liniac` Beam Monitor OHO'86, High Energy 
Accelerator Seminar; Beam Monitor and Beam Instability, p. 4-1 (1986)" as 
the prior art, the starting operation of a circular accelerator and change 
of operation parameters are manually performed by observing the outputs of 
monitors such as a profile monitor, position monitor, and current monitor 
in accordance with previously calculated parameters. 
The prior art is described below by taking the electron storage ring in 
FIG. 2 as an example. Electron beams obtained from a front accelerator 10 
are shaped, aligned, and energy-sorted by an electromagnet group called a 
beam transfer system 11 and then applied to an electron storage ring 12. 
Thereafter, the electron beams are held on a certain orbit (hereafter 
referred to as a closed orbit) by the electromagnet group of the storage 
ring 12. Moreover, the electron beams are accelerated or kept in a storage 
state by receiving energy from an accelerating cavity 22 in the storage 
ring. This series of operations are called beam adjustment and is manually 
performed in the prior art while observing the outputs of various monitors 
set in the beam transfer system 11. The storage ring 12 and the operation 
of such an accelerator depends on experts. In the case of the above prior 
art, the starting operation and change of operation parameters are not 
easy because the beam adjustment is manually performed. Moreover, because 
the beam adjustment is manually performed in the case of the prior art, 
there are problems that a true operation parameter cannot easily be 
determined because there are too many parameters (e.g. exciting current of 
an electromagnet) to be determined and the beam adjustment greatly depends 
on the skill of an operator. 
As other prior art, an accelerator for previously storing an exciting 
current to be supplied to a corrective electromagnet (for correcting the 
orbit of an electron beam) when a charged particle beam is injected into 
or extracted from a synchrotron and supplying the exciting current to the 
corrective electromagnet at a predetermined timing is disclosed in the 
official gazette of Japanese Patent Laid-Open No. 169100/1992. 
Moreover, a control method for detecting a beam current taken out of a 
synchrotron and controlling the exciting current of an electromagnet so 
that the beam current is maximized is disclosed in the official gazette of 
Japanese Patent Laid-Open No. 140999/1983. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide an operating method of 
an accelerator, an accelerator, and an accelerating system for realizing 
automatic operation in all modes of the accelerator without depending on 
the skill of an operator. 
The above object is achieved by using data for injection energy, storage 
energy, and accelerating time of a charged particle beam of an 
accelerator, thereby obtaining operating patterns of components of the 
accelerator, and controlling the components in accordance with the 
obtained operating patterns. 
Moreover, the above object is achieved by using data for injection energy, 
storage energy, accelerating time, extraction energy, and extraction 
current of a charged particle beam of an accelerator, thereby obtaining 
operating patterns of components of the accelerator, and controlling the 
components in accordance with the obtained operating patterns. 
Furthermore, the above object is achieved by using an operating method of 
an accelerator provided with a first component for bending a charged 
particle beam and a second component for correcting the orbit of the beam, 
in which beam transfer is controlled for each of the components from the 
upstream side toward the downstream side of the traveling direction of the 
beam and thereafter beam transfer is controlled by relating all the 
components to each other from the upstream side toward the downstream side 
of the traveling direction of the beam. 
Furthermore, the above object is achieved by using an operating method of 
an accelerator provided with a first component for bending a charged 
particle beam and a second component for correcting the orbit of the beam, 
in which a control signal is generated by using a beam current at two 
optional points at both sides of the components to control the components 
between the two points in accordance with the control signal. 
The present invention makes it possible to automatically operate an 
accelerator without depending on the skill of an operator in all operation 
modes such as the starting operation, steady operation, and change of 
operating conditions by using data for injection energy, storage energy, 
and accelerating time of a charged particle beam, thereby obtaining 
operating patterns necessary for components of the accelerator such as a 
bending magnet for bending the beam, an orbit correction magnet for 
correcting the orbit of the beam, and an accelerating cavity for 
accelerating the beam, and controlling the components in accordance with 
the obtained operating patterns. 
Moreover, the present invention makes it possible to automatically operate 
an accelerator in all operation modes without depending on the skill of an 
operator by using data for injection energy, storage energy, accelerating 
time, extraction energy, and extraction current of a charge particle beam, 
thereby obtaining operating patterns necessary for components such as a 
bending magnet for bending the beam, an orbit correction magnet for 
correcting the orbit of the beam, an accelerating cavity for accelerating 
the beam, and an extracting apparatus for extracting the beam, and 
controlling the components in accordance with the obtained operating 
patterns. 
Furthermore, the present invention makes it possible to automatically 
operate an accelerator provided with a first component for bending a 
charged particle beam and a second component for correcting the orbit of 
the beam in all operation modes without depending on the skill of an 
operator by using an operating method of the accelerator, in which an 
optimum parameter for beam transfer obtained by correcting the 
combinational relation between components due to a leakage magnetic field 
can be determined by controlling the beam transfer for each of the 
components from the upstream side toward the downstream side of the 
traveling direction of the beam, thereafter relating all the components to 
each other from the upstream side toward the downstream side, and thereby 
controlling the beam transfer. 
Furthermore, the present invention makes it possible to determine an 
optimum parameter for beam transfer obtained by correcting the 
combinational relation between components due to a leakage magnetic field 
and to automatically operate an accelerator in all operation modes without 
depending on the skill of an operator by using an operating method of an 
accelerator provided with a first component for bending a charged particle 
beam and a second component for correcting the orbit of the beam, in which 
both the beam transfer for each component and the beam transfer relating 
all components to each other can be controlled by using a beam current 
value at two optional points at both sides of the components to generate a 
control signal, and controlling the components between the two points in 
accordance with the control signal.

BEST MODE FOR CARRYING OUT THE INVENTION 
Embodiments of the present invention are described below by referring to 
the accompanying drawings. FIG. 1 is an illustration showing the first 
embodiment obtained by applying the present invention to a semiconductor 
aligner and FIG. 3 is an illustration showing the details of the 
controller in FIG. 1. 
The semiconductor aligner of the first embodiment comprises the body of an 
accelerator for generating, accelerating, and storing an electron beam, a 
pattern transferring apparatus 500 for transferring a desired pattern onto 
a semiconductor substrate by using a radiation beam 501 extracted from the 
body of the accelerator, and a controller 400 for mainly controlling a 
plurality of components of the body of the accelerator. 
The body of the accelerator comprises a front accelerator 10 for generating 
an electron beam, a beam transfer system 11 for transferring the electron 
beam generated by the front accelerator 10 to a storage ring 12, and a 
storage ring 12 for accelerating and storing the electron beam. A beam 
orbit in these components is enclosed by a vacuum duct 25 whose inside is 
evacuated to provide a vacuum. The beam transfer system 11 comprises a 
bending magnet 20 for bending an electron beam, a quadrupole magnet 21 for 
performing convergence and divergence of an electron beam, and current 
monitors 320 to 324 for measuring the beam current of the electron beam. 
The storage ring 12 comprises an injector 23 for injecting an electron 
beam into a storage ring, the bending magnet 20, the quadrupole magnet 21, 
a steering magnet 26 for fine-adjusting the position of the electron beam, 
the accelerating cavity 22 for accelerating the electron beam, and current 
monitors 320 to 338. The current monitors 320 to 338 are arranged at the 
front and rear of the bending magnet 20 so as to sandwich the magnet 20. 
The controller 400 for monitoring and controlling the operation of an 
accelerator, as shown in FIG. 3, comprises an input section which includes 
a beam current measuring apparatus 42 for receiving input data from the 
current monitors 320-338 and measuring the beam current of an accelerator 
at a predetermined timing and a quantity-of-control measuring apparatus 43 
for receiving input data from the front accelerator 10 and the elements 20 
to 26 and measuring the temperature of a cathode of the front accelerator 
10 or the quantity of control such as the exciting current of the bending 
magnet 20, quadrupole magnet 21, and steering magnet 26 at a predetermined 
timing. The controller 400 also comprises a quantity-of-control 
determining apparatus 44 for determining the quantity of control of each 
component at a predetermined timing; a trigger generating apparatus 41 for 
generating trigger signals (hereafter referred to as various trigger 
signals) for measurement of beam current by the beam current measuring 
apparatus 42, measurement of quantity of control by the 
quantity-of-control measuring apparatus 43, determination of quantity of 
control by the quantity-of-control measuring apparatus 44, and injection, 
extraction, acceleration, and deceleration of an electron beam of an 
accelerator; and a main controller 40 which performs arithmetic operations 
for determining the quantity of control and the control timing of every 
component. 
The quantity-of-control determining apparatus 44, as shown in FIG. 5, 
comprises a buffer 441 for holding a control signal 81 outputted from the 
main controller 40 and a D-A converter 442 for converting a digital signal 
to an analog signal in accordance with a determination trigger signal 99 
outputted from the trigger generating apparatus 41. 
The quantity-of-control measuring apparatus 43, as shown in FIG. 6, 
comprises a sample hold circuit 431 for holding a monitor signal outputted 
from a power supply for the front accelerator 10 and various magnets when 
a measurement trigger signal 97 is outputted from the trigger generating 
apparatus 41, an A-D converter 432 for converting an analog signal held by 
the sample hold circuit 431 to a digital signal, and a buffer 434 for 
accumulating digital signals. 
The beam current measuring apparatus 42, as shown in FIG. 7, comprises a 
sample hold circuit 421 for holding a monitor signal outputted from the 
current monitors 320 to 338, an A-D converter 422 for converting an analog 
signal held by the sample hold circuit 421 to a digital signal, and a 
buffer 424 for accumulating digital signals. 
The trigger generating apparatus 41, as shown in FIG. 8, comprises a master 
oscillator 412, a distributor 413 for distributing a single output of the 
master oscillator 412 to a plurality of outputs, a delaying unit 414 for 
giving a proper delay time to each trigger signal for quantity-of control 
determination, quantity-of control measurement and beam current 
measurement, a distributor 415 for distributing the output of the delaying 
unit 414 to the front accelerator 10 and the injector 23, a delaying unit 
416 for giving an intrinsic delay time necessary for the front accelerator 
10 and the injector 23 to the output of the distributor 415, a device 411 
for determining a delay time outputted by the delay circuits 414 and 416, 
and an OR circuit for operating the beam current measuring apparatus 42 
when either of a trigger signal 93 for measuring beam current and a 
trigger signal 94 for confirming the number of accumulated beams is 
inputted. It is also possible to use a constitution in which the output of 
the master oscillator 412 is directly inputted to the distributor 415. 
FIG. 9 shows the connection between the bending magnet 20, quadrupole 
magnet 21, and steering magnet 26 on the hand and the quantity-of-control 
measuring apparatus 43 and the quantity-of-control determining apparatus 
44 on the other. A magnet power supply 201 comprises an exciting-current 
monitor 202 for measuring the exciting current of a magnet (20, 21, or 26) 
which is a load, a current source 203 for supplying an exciting current to 
a magnet, and a feedback circuit 204 for controlling the output current of 
the current source 203. The feedback circuit 204 compares a determined 
value of the magnet exciting current outputted from the 
quantity-of-control determining apparatus 44 with a measured value of the 
exciting current measured by the exciting current monitor 202 and sets the 
difference between the determined value and the measured value to the 
current source 203. At the same time, the exciting current measured by the 
exciting current monitor 202 is transmitted to the quantity-of-control 
measuring apparatus 43. 
The main controller 40 is connected with the beam current measuring 
apparatus 42, quantity-of-control measuring apparatus 43, and 
quantity-of-control determining apparatus 44 by a parallel cable so that 
data can be transferred bidirectionally between them. 
The starting operation of the body of the accelerator in FIG. 1 is 
described below by referring to the flow chart shown in FIG. 4. An 
electron beam is generated by the front acceleration 10, and the energy 
and profile of the beam are arranged by the beam transfer system 11 and 
injected into the storage ring 12. Thereafter, the electron beam is 
accelerated by a synchrotron and accumulated in the storage ring 12. This 
series of acceleration operating methods is summarized below. 
(1) Control signals 81 for the initial value, variable range, and variable 
step (width) of the quantity of control of each component of the 
accelerator are outputted from the main controller 40 to the 
quantity-of-control determining apparatus 44, and moreover various trigger 
signals 91 and 92 for the determining cycle and measuring cycle of 
quantity of control, and the injection timing, acceleration timing, 
deceleration timing, acceleration pattern, and deceleration pattern of the 
beam are outputted from the main controller 40 to the trigger generating 
apparatus 41. 
(2) Each component are made to wait under the stage of the initial 
determined value. 
(3) A beam output signal 96 is transmitted from the trigger generating 
apparatus 41 to the front accelerator 10 to generate an electron beam 
(step 150 in FIG. 4) and a measurement trigger signal 93 is transmitted to 
the beam current measuring apparatus 42. 
(4) Regarding the quantity of control of the components between current 
monitors, the variable range determined in the above Item (1) is 
sequentially searched for each variable step along the traveling direction 
of a beam from the current monitor 320 to the current monitor 324 in the 
beam transfer system 11 so that the output of the downstream-side monitor 
out of two consecutive monitor signals is maximized, in other words, the 
transmittance is maximized. For example, the exciting current of the 
bending magnet 20 is controlled in the case of the current monitors 320 
and 321 and the exciting currents of two quadrupole magnets 21 are 
controlled in the case of the current monitors 323 and 324. 
Thus, beam transfer in the beam transfer system 11 is started (step 151 in 
FIG. 4). 
(5) The operation the same as that in Item (4) is performed between the 
current monitors 324 and 330 to inject an electron beam into the storage 
ring (step 152 in FIG. 4). 
(6) The operation the same as that in Item (4) is performed between the 
current monitors 330 and 338 to perform beam transfer in the storage ring 
12 (step 153 in FIG. 4). 
By the above operations (4) to (6), that is, by maximizing the output of 
the current monitor 338, orbiting of the electron beam in the storage ring 
12 is confirmed. At this stage, however, the number of accumulated 
electron beams is not confirmed. 
The number of accumulated electron beams can be confirmed by the fact that 
the time width of the output signal of any current monitor (any one of the 
current monitors 330 to 338) increases with passage of time. 
(7) The trigger signal 94 for confirming the number of accumulated beams is 
generated by the trigger generating apparatus 41 a sufficient time (time 
required for an electron beam to orbit in the storage ring 100 to 200 
times) after the beam output signal 96 is sent to the front accelerator 10 
to sequentially search the exciting currents of the bending magnet 20 and 
the quadrupole magnet 21 in the storage ring 12 so as to maximize the beam 
current signal obtained from the current monitor 338 (step 154 in FIG. 4). 
By the above operation, the number of accumulated electron beams is 
confirmed and coarse adjustment as the acceleration preparing stage is 
completed. 
(8) The determined value is adjusted for each variable step and each 
component again in the variable range determined in Item (1) starting with 
the initial component of the beam transfer system 11 so that the monitor 
signal or the storage current of the current monitor 338 at the lowest 
downstream side of the storage ring 12 is maximized. 
The fine adjustment in Item (8) is necessary because of the following 
reasons. In the case of a beam obtained from the front accelerator 10, the 
energy is almost known but the position and gradient are not known. 
Moreover, the ranges of energy, position, and gradient which can be 
captured by a storage ring or synchrotron are not large in general (e.g. 
approx. 1%). Therefore, the beam transfer parameter obtained in Item (7) 
serves as a correct parameter when magnet systems for performing beam 
transfer are independent of each other. In fact, however, because the 
magnets are loosely combined due to the multipole magnetic field 
component, leakage magnetic field, setting error of the magnets, a desired 
energy, position, and gradient are not always obtained. To finally 
maximize the output of the current monitor set at the final stage, the 
outputs of the current monitors during beam transfer are not maximized in 
most cases. Thereafter, an optimum parameter for beam transfer can be 
determined by adjusting each component used for beam transfer so as to 
maximize the output of the current monitor at the final stage as described 
in the above Item (8). 
Thus, the preparation conditions for acceleration in FIG. 4 are determined. 
(9) The data for the acceleration pattern obtained in Item (1) is corrected 
in accordance with the determined values of the components of the storage 
ring 12 obtained in Item (8) and the acceleration trigger signal is 
transmitted to each component to perform acceleration (step 155 in FIG. 
4). 
(10) While acceleration is performed, the measurement trigger signal 93 is 
transmitted from the trigger generating apparatus 41 to the beam current 
measuring apparatus 42 to measure the change of the beam current under 
acceleration. In this case, if the electron beam emits a radiation beam, 
it is possible to measure the luminous energy of the radiation. If it is 
found from the measurement result that the beam current suddenly changes, 
the position is determined and the determined value of the component 
arranged at the determined position is adjusted for each step in the 
variable range determined in Item (1). 
(11) The operations in Items (9) to (10) are repeated until the storage 
current does not suddenly change. 
The operations in Items (9) to (11) are executed until the ratio of the 
storage current at the end of acceleration to the storage current before 
acceleration is maximized. By these operations, electrons are accelerated 
and accumulated up to a desired energy (step 156 in FIG. 4). 
(12) When a predetermined storage time has passed or the storage current 
has come to a predetermined storage current value or less after succeeding 
in acceleration, the storage is terminated and a trigger signal for 
deceleration is transmitted to each unit to perform deceleration in 
accordance with the data for a predetermined deceleration pattern (step 
157 in FIG. 4). 
Thus, one operation cycle terminates. 
In the above case, the transmission value of the beam current between two 
consecutive current monitors is maximized. It is also possible to 
similarly perform beam transfer between two optional monitors. Moreover, 
it is possible to set the current transmission value to not only the 
maximum value but also a desired value. 
Then, judgment on the quality of beam transfer is described below in 
detail. As described above, the determined value, initial value, final 
value, increment, delay time, and patterns of various trigger signals are 
first computed in the main controller 40 for beam transfer and computed 
values are set to each unit. Then, an operation start signal (beam-on, 
beam output signal for the front accelerator 10) is transmitted from the 
main controller 40 to the trigger generating apparatus 41. Thereby, the 
output signal of the master oscillator 412 is transmitted to the 
distributor 413 and various trigger signals distributed by the distributor 
413 are delayed by the delay time intrinsic to each unit and transmitted 
to each unit. 
First, current values of the power supplies of the bending magnet 20, 
quadrupole magnet 21, steering magnet 26, and accelerating cavity 22 are 
determined to apply current to each load. The current is measured by using 
a current monitor (mainly, shunt resistance in the case of a magnet power 
supply) and the quantity-of-control measuring apparatus 43 to transfer the 
measured value 98 to the main controller 40. At the same time, the beam 
current is measured by using the current monitors 320 to 338 set to the 
body of an accelerator and the beam current measuring apparatus 42 to 
transfer the measured value 82 to the main controller 40. 
By the above operations, the main controller 40 judges the quality of beam 
transfer in accordance with a predetermined value and the beam-current 
measured value 82 and repeats the operation until beam transfer succeeds. 
At the acceleration stage, the quantity of control and the beam current 
under acceleration can be measured by previously setting an acceleration 
pattern to the quantity-of-control measuring apparatus 44, thereafter 
transmitting an acceleration trigger signal from the main controller 40 to 
the trigger generating apparatus 41, and holding the signal until 
acceleration terminates. Thus, the quality of acceleration can be judged. 
The starting method of the body of an accelerator is described above. For 
the steady operation in which operating conditions are constant, however, 
the occurrence, injection, acceleration, storage, and deceleration of a 
beam are pattern-operated in accordance with the operating patterns 
obtained in the above Items (1) to (12) as shown in FIG. 10. To change the 
operating conditions, a new parameter is determined at first, an operating 
pattern is corrected in accordance with the parameter, and thereby the 
pattern operation from generation to deceleration of a beam is performed. 
Then, the second embodiment obtained by applying the present invention to a 
semiconductor aligner is described below by referring to FIG. 12. The body 
of the accelerator of this embodiment comprises a front accelerator 10 for 
generating an electron beam, a beam transfer system 11 for transferring 
the electron beam generated by the front accelerator 10 to an accelerating 
synchrotron 13, the accelerating synchrotron 13 for accelerating the 
electron beam, a beam transfer system 14 for transferring the electron 
beam accelerated to a high energy from the accelerating synchrotron 13 to 
a storage ring 12, and the storage ring 12 for accumulating electron 
beams. 
This is an independent constitution as the accelerating synchrotron 13 by 
using the electron-beam accelerating function of the storage ring 12 of 
the embodiment shown in FIG. 1. 
FIG. 13 shows an operating method of the body of the accelerator in FIG. 
12. Though the flow of the operating method in FIG. 13 is almost the same 
as that in FIG. 4, beam extraction from the accelerating synchrotron 13, 
beam transportation (beam transfer 3) in the beam transfer system 14, and 
beam injection (injection 2) to the storage ring 12 are newly added. 
However, the adjustment method using the current monitors 320 to 338 in 
FIG. 1 can also be applied to the current monitors 320 to 347 in FIG. 10. 
Moreover, the trigger generating apparatus 41 shown in FIG. 8 is 
constituted so as to also generate the trigger signals for beam extraction 
from the accelerating synchrotron 13 and beam injection to the storage 
ring 12. 
Furthermore, by setting a beam distributing magnet in the beam transfer 
system 14 for connecting the accelerating synchrotron 13 with the storage 
ring 12 in FIG. 12, it is also possible to constitute an accelerator 
system for supplying electron beams extracted from the accelerating 
synchrotron 13 to a plurality of storage rings 12. 
Then, the third embodiment obtained by applying the present invention to a 
medical system is described below by referring to FIG. 14. This embodiment 
comprises a front accelerator 10 for generating a charged particle beam, a 
beam transfer system 11 for transferring the charged particle beam 
generated by the front accelerator 10 to an accelerating synchrotron 13, 
the accelerating synchrotron for accelerating the charged particle beam, a 
beam transfer system 15 for transferring the charged particle beam 
accelerated to a high energy from the accelerating synchrotron 13 to an 
irradiation room 16, and the irradiation room 16 for performing 
irradiating treatment by using the charged particle beam. 
Charged particle beams accelerated by the accelerating synchrotron 13 are 
extracted from an extractor 27 and distributed to a plurality of 
irradiation rooms 16 in order by a distributing magnet 28 set in the beam 
transfer system 15. 
FIG. 15 shows an operating method of the medical system in FIG. 14. When 
using an charged particle beam for irradiation therapy, it is necessary to 
change an acceleration energy and electron beam current (dose) in 
accordance with the depth of the affected part of a patient to be 
irradiated with a charged particle beam. The acceleration energy is 
determined by the final value of the data for the acceleration pattern of 
the bending magnet 20 of the accelerating synchrotron 13 and the final 
value is previously determined. 
Then, methods for transferring charged particle beams up to a plurality of 
irradiating rooms while controlling the beam current are described below. 
In the case of the first method, the quantity of control for each 
component up to each irradiating room 16 is determined so that the output 
signals of the current monitors 320 to 346 set for each bending magnet 20 
are maximized or the attenuation of the beam current at the position of a 
current monitor of the downstream side to the position of a current 
monitor of the upstream side is minimized when no patient is present in 
the irradiating room 16. Thus, the operation parameter of the accelerator 
system is determined. In this case, the outputs of the current monitors 
344, 345, and 346 immediately before the irradiating rooms 16 are stored. 
The outputs are converted into doses and the beam current generated by the 
front accelerator 10 is increased or decreased so as to meet a 
predetermined dose requirement in the irradiating room 16. 
In the case of the second method, the procedure is the same as the first 
method up to the determination of the operation parameter of the 
accelerating synchrotron 13 but up to the step of extraction in FIG. 15 is 
performed so that the beam current is maximized. Thereafter, a damper 29 
is inserted in the middle of the beam transfer system 15 so that the beam 
current at the position where the beam transfer system 15 is present comes 
to a desired beam current. The damper 29 uses, for example, a scatterer to 
decrease the beam current by scattering. By using the damper 29, it is 
possible to change the dose for each irradiating room. In this case, means 
for monitoring the beam current can use means for directly measuring the 
beam current or means for measuring a radiation dose or the like caused by 
collision between a beam and a material. This method makes it possible to 
irradiate a patient with a desired dose at a desired energy. 
Moreover, if a trouble occurs in any one of the components constituting an 
accelerator, it is possible to specify the defective component at the 
position of a current monitor with an extremely small beam current by 
continuously monitoring the current monitors set to various positions. 
Therefore, it is possible to detect by and display on a controller a 
defective component. 
Industrial Applicability 
As described above, the present invention makes it possible to provide an 
operating method of an accelerator to be automatically operated without 
depending on the skill of an operator in every operation mode, such as 
startup and steady operations and operation condition change, the 
accelerator, and an accelerating system.