A
synchrocyclotron is a
cyclotronA cyclotron is a type of particle accelerator. Cyclotrons accelerate charged particles using a high-frequency, alternating voltage...
in which the frequency of the driving
RFRadio frequency is a frequency, or rate of oscillation, of electromagnetic radiation within the range of about 3 Hz to 300 GHz. This range corresponds to the frequency of alternating current electrical signals used to produce and detect radio waves...
electric fieldIn physics, the space surrounding an electric charge or in the presence of a time-varying magnetic field has a property called an electric field. This electric field exerts a force on other electrically charged objects...
is varied to compensate for the mass gain of the accelerated particles as their velocity begins to approach the
speed of lightIn physics, the speed of light is a physical constant, the speed at which electromagnetic radiation, such as light, travels in free space . Its value is 299,792,458 metres per second...
. This is in contrast to the classical cyclotron, where the frequency was held constant.
The two fundamental differences between this machine and the orthodox cyclotron are that
- in this machine, only one dee
Dee might refer to:*D, a letter*"Dee" , a song by Randy Rhoads*Dee , Puerto Rican pornographic actress*Dee , Canadian electro-pop singer, songwriter and DJ*Dead-end elimination...
is used instead of two
- the frequency of oscillating electric field is made to decrease continuously instead of keeping it constant so as to maintain the resonance with ion frequency.
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A
synchrocyclotron is a
cyclotronA cyclotron is a type of particle accelerator. Cyclotrons accelerate charged particles using a high-frequency, alternating voltage...
in which the frequency of the driving
RFRadio frequency is a frequency, or rate of oscillation, of electromagnetic radiation within the range of about 3 Hz to 300 GHz. This range corresponds to the frequency of alternating current electrical signals used to produce and detect radio waves...
electric fieldIn physics, the space surrounding an electric charge or in the presence of a time-varying magnetic field has a property called an electric field. This electric field exerts a force on other electrically charged objects...
is varied to compensate for the mass gain of the accelerated particles as their velocity begins to approach the
speed of lightIn physics, the speed of light is a physical constant, the speed at which electromagnetic radiation, such as light, travels in free space . Its value is 299,792,458 metres per second...
. This is in contrast to the classical cyclotron, where the frequency was held constant.
The two fundamental differences between this machine and the orthodox cyclotron are that
- in this machine, only one dee
Dee might refer to:*D, a letter*"Dee" , a song by Randy Rhoads*Dee , Puerto Rican pornographic actress*Dee , Canadian electro-pop singer, songwriter and DJ*Dead-end elimination...
is used instead of two
- the frequency of oscillating electric field is made to decrease continuously instead of keeping it constant so as to maintain the resonance with ion frequency. One terminal of the oscillating electric potential varying periodically is applied to the dee and the other terminal is earthed. The proton or deuterons to be accelerated are made to move in circles of increasing radii. The acceleration of particles takes place as they enter or leave D. at the outer edge, the ion beam can be removed with the aid of electrostatic deflector. It was possible to produce 200MeV deuterons and 400MeV α-particle with the first synchrocyclotron
Synchrocyclotrons have not been built since the isochronous cyclotron was developed.
Isochronous cyclotronIn particle accelerators an Isochronous cyclotron is a cyclotron that maintains a constant RF driving frequency, and compensates for the relativistic mass gain of the accelerated particles by increasing the magnetic field with radius...
s maintain a constant RF driving frequency and compensate for the relativistic mass gain of the accelerated particles by increasing the magnetic field with radius. Isochronous cyclotrons are capable of producing much greater beam current than synchrocyclotrons.
Advantages
The chief advantage of the synchrocyclotron is that there is no need to restrict the number of revolutions executed by the ion before its exit. As such, the potential difference supplied between the dees can be much smaller.
The smaller potential difference needed across the gap has the following uses:
- There is no need for a narrow gap between the dees as in the case of convention cyclotron, because strong electric fields for producing large acceleration are not required. Thus only one dee can be used instead of two, the other end of the oscillating voltage supply being connected to earth.
- The magnetic pole pieces can be brought closer, thus making it possible to increase greatly the magnetic flux density.
- The frequency valve oscillator is able to function with much greater efficiency.
The main drawback of this device is that, as a result of the variation in the frequency of the oscillating voltage supply, only a very small fraction of the ions leaving the source are captured in phase-table orbits of maximum radius and energy so that the output beam current is rendered weak. Thus the machine produces high energy ions, though of small intensity
See also
- Cyclotron
A cyclotron is a type of particle accelerator. Cyclotrons accelerate charged particles using a high-frequency, alternating voltage...
— this contains a mathematics section that assumes constancy of mass, and an extensive see also section.
- Betatron
A betatron is a cyclotron developed by Donald Kerst at the University of Illinois in 1940 to accelerate electrons. The betatron is essentially a transformer with a torus-shaped vacuum tube as its secondary coil...