Device and method for fast beam current modulation in a particle accelerator

A circular particle accelerator for generating a beam of charged particles comprising:

• an ion source configured to generate the charged particles;
• accelerating electrodes separated from each other by gaps;
• a generator configured to apply an alternating voltage to the accelerating electrodes to accelerate the charged particles in an electric field in the gaps and form a beam current;
• and
• a regulator connected with the generator, the regulator configured to control the amplitude of the alternating voltage applied to the accelerating electrodes, the regulator configured to cut-off the beam current by effecting the generator to apply to the accelerating electrodes a voltage with an amplitude below a threshold voltage where the beam current is cut-off and dark current is not produced by the circular particle accelerator.

A method for cutting-off beam current in a circular particle accelerator, the method comprising:

• generating charged particles from an ion source;
• accelerating the charged particles by applying with a generator an alternating voltage to accelerating electrodes in the circular particle accelerator to accelerate the charged particles in an electric field in gaps between the accelerating electrodes and to produce the beam current, wherein different voltage amplitudes result in different amounts of energy gained by the charged particles in the electric field in the gaps;
• and
• cutting-off the beam current by reducing the amplitude of the alternating voltage applied to the accelerating electrodes below a threshold value, where dark current is not produced by the circular particle accelerator.

A circular particle accelerator for generating a beam of charged particles comprising:

• an ion source configured to generate the charged particles;
• accelerating electrodes separated from each other by gaps;
• a generator configured to apply an alternating voltage to the accelerating electrodes to accelerate the charged particles in an electric field in the gaps and to form a beam current;
• a collimator configured for stopping charged particles having an orbit radius less than or equal to a critical orbit radius;
• and
• a regulator connected with the generator, the regulator configured to control an amplitude of the alternating voltage applied to the accelerating electrodes, wherein different voltage amplitudes result in different orbit radii of the charged particles, and a voltage amplitude below a threshold value results in an orbit radius less than said critical orbit radius, the regulator configured to cut-off the beam current by effecting the generator to apply to the accelerating electrodes a voltage with an amplitude below said threshold value.

A method for cutting-off a beam current in a circular particle accelerator, the circular particle accelerator comprising:

• an ion source configured to generate charged particles;
• accelerating electrodes separated from each other by gaps;
• a generator configured to apply an alternating voltage to the accelerating electrodes configured to accelerate the charged particle beam in an electric field in the gaps and to form the beam current;
• a collimator configured for stopping charged particles having an orbit radius less than or equal to a critical orbit radius;
• and
• a regulator connected with the generator, the regulator configured to modulate an amplitude of the alternating voltage applied to the accelerating electrodes, wherein different voltage amplitudes result in different orbit radii of the charged particles, and the circular particle accelerator is configured so that a voltage amplitude below a threshold value results in an orbit radius less than said critical orbit radius;
• wherein the beam current is cut-off by applying to the accelerating electrodes a voltage with an amplitude below said threshold value.

A circular particle accelerator for generating a beam of charged particles comprising:

• an ion source configured to generate the charged particles;
• accelerating electrodes separated from each other by gaps;
• a generator configured to apply an alternating voltage to the accelerating electrodes to accelerate the charged particles in an electric field in the gaps and to form a beam current;
• and
• a regulator connected with the generator, the regulator configured to vary an amplitude of the alternating voltage applied to the accelerating electrodes, wherein different voltage amplitudes result in effecting at least one different set point value where dark current is not produced by the accelerator.