This type of gas pedal will DC high voltage on a pair or a series of series connected accelerating electrodes, charged particles through the gap between the electrodes, accelerated by a high voltage electric field, to get the same voltage equivalent energy. According to the different forms of DC high voltage power supply, this gas pedal can be divided into doubling circuit gas pedal and electrostatic
electric gas pedal two categories.
Boosting circuit gas pedals are high-voltage doubler (also known as series-excited doubling rectifier, or Cocker Rauf-Walton generator), "ground Naomi" gas pedal (also known as parallel excitation of high-frequency high-frequency voltage generator), Marx pulse doubling generator, insulated core transformer and so on. These devices are suitable for generating high voltages in the range of tens of kilovolts to several megavolts and can provide high beam power. Most of the high-voltage doubler voltage between 100 ~ 600kV, mainly used to produce (d, d) or (d, t) reaction of the neutron generator and the development of semiconductor devices and ion implantation machine; voltage in the 1 ~ 4MV of the "ground that rice" and insulated core transformer is mainly used to accelerate the high-power electron beam (tens of milliamps) for the Irradiation process. Marx pulse voltage doublers are used to generate pulsed electron beams with intensities of tens of kiloamps. Electrostatic Accelerator Particle Accelerator
Also known as the Vandergriff Accelerator, it is used to accelerate particles by continuously delivering an electric charge to hollow metal electrodes through a transmission belt or chain to charge them to a high voltage. The entire gas pedal is installed in a closed high-pressure container, the typical operating voltage of 2 to 10 MV, the accelerated particle flow can be tens to hundreds of microamps. Most ion electrostatic gas pedals are used for neutron reaction cross-section measurements, ion beam microanalysis, and research in atomic and molecular physics, while electron electrostatic gas pedals are used for irradiation processing, sterilization and other aspects. In recent years, the production of a number of voltage 1 ~ 2 MV small tandem gas pedals, they have a wide range of uses in elemental trace analysis and so on.
DC high-voltage gas pedal *** with the same characteristics is to accelerate any kind of charged particles, and energy can be smoothly adjusted. But the energy of this type of gas pedal DC by the material breakdown voltage limitations, can not be too high. In order to accelerate particles to a higher energy, the development of electromagnetic induction and resonance type gas pedal.
Electromagnetic induction gas pedal
Particle gas pedal
The use of alternating magnetic field generated by the vortex electric field to accelerate the acceleration of charged particles, including the common electron induction gas pedal and the development of ion linear induction gas pedal. The former uses an axisymmetric alternating magnetic field with a special distribution to guide electrons along a circular orbit of constant radius. At the same time, a vortex electric field induced by this magnetic field accelerates the electrons to high energies. Typical electron induction gas pedals have energies around 25 MeV. During acceleration, the electron is spun more than a million times.
The electron induction gas pedal's current intensity is low, usually no more than 0.5 μA. The resulting bremsstrahlung radiation is about 10 ~ 1Gy/min at 1m from the target, which is mainly used for non-destructive flaw detection of metal components, irradiation of tumors, etc. The University of Illinois has built a new facility with an energy of 25 MeV. The University of Illinois has built an electron induction gas pedal with an energy of 300 MeV. Due to the circular orbit of the induction gas pedal is not suitable for accelerating ions, in recent years proposed a linear induction gas pedal, is planned to be used to accelerate 10 kA of heavy ion flow, is still in the development stage.
Linear resonance gas pedal
An gas pedal that accelerates particles along a linear track under the action of a high-frequency electric field. In order to make the particles in the not too long distance accelerated to the final energy, high-frequency electric field amplitude is usually 1 ~ 10MV/m. This requires the use of very high power level of high-frequency, microwave power supply to stimulate the acceleration cavity. Such power sources often only work in a pulsed state. The main advantage of gas pedals is the high intensity of the beam of accelerated particles and the fact that their energy can be increased section by section without restriction. The disadvantage is that the power consumption of high-frequency operation is large, and the equipment investment is high. A variety of low-temperature superconducting linear acceleration structures have been developed in recent years. Superconducting linear gas pedals (see superconducting gas pedal) can reduce operating costs by a factor of 3 to 5, in principle, can provide a continuous particle beam cluster.
Cyclotron resonant gas pedal
Particle gas pedal
A type of circular-orbit gas pedal that applies a high-frequency electric field to accelerate particles. The particles in this type of gas pedal move in a cyclotron motion under the control of a guided magnetic field, repeatedly passing through the accelerating electric field region and being accelerated several times until they reach the rated energy. Cyclotron resonant gas pedals can be divided into two categories. In the first category, the magnetic field does not change with time, and the radius of curvature of the accelerated particles increases continuously with the increase of energy. Classical cyclotrons, sector-focused cyclotrons, synchrotrons and electron cyclotrons belong to this category. In the other category, the strength of the guiding magnetic field increases with the momentum of the particle, but the radius of curvature of the particle remains constant. For example, electron synchrotrons and proton synchrotrons belong to this category. In the above gas pedals, except for the sector focusing cyclotron, there is the phenomenon of automatic phase stabilization.
Cyclotron particle gas pedal
The classical cyclotron has a magnet that generates a uniform magnetic field, and a pair of hollow "D" shaped high frequency electrodes. A high-frequency accelerating electric field of fixed frequency is applied between the electrodes. When the energy of the particles is low, their rotational frequency resonates with the high-frequency field, and they are accelerated once every half turn. However, when the energy is high, the rotational frequency of the particles becomes lower and lower than the frequency of the electric field as the energy increases, which ultimately leads to the fact that they can no longer be accelerated by the electric field. For this reason, the maximum energy of a proton in a classical cyclotron is only about 20 Me V. To overcome this difficulty, the magnetic field can be increased gradually along the radius so that the rotational period of the particle remains constant. However a magnetic field that is simply raised along the radius causes the particle beam to scatter in the axial direction and cannot be applied.
Synchronous cyclotron
A cyclotron in which the frequency of the accelerating electric field is kept constant by a magnetic field that decreases synchronously with the rotational frequency of the particles, also known as a frequency-modulated cyclotron or phase-stabilized gas pedal. According to the principle of automatic phase stabilization, with such acceleration, protons can in principle be accelerated to infinitely high energies. However, the largest synchrotron in history has only reached an energy of 700 MeV. This is due to the fact that its magnet weighs 7,000 tons, which is more than the weight of a typical high-energy gas pedal magnet. Economically and technically it is not advisable to build higher energy FM gas pedals, because the frequency of the electric field must change over time, the synchrotron can only work in a pulsed state. Pulse repetition rate of about 30 ~ 100Hz, the average current strength of a few microamps, than the energy of comparable sector focusing cyclotron small one or two orders of magnitude. For this reason, many synchrotrons have been closed, and some have been converted to isochronous cyclotrons.
Electron cyclotron
Also known as a microwave cyclotron, it is dedicated to the acceleration of electrons. With the classical cyclotron, the gas pedal's magnetic field is uniform, the frequency of the accelerating electric field is also constant, the difference is that the accelerating gap is located at one end of the magnetic pole, the electron's orbit is a series of tangent to the center line of the accelerating gap of the circle, the electron is accelerated every time after the rotational period of the acceleration just to increase to an integral multiple of the accelerated before, and thus whenever these electrons are turned back to the accelerating gap, the electric field is just enough to make them Accelerate again. Most electron gas pedals have energies between 10 and 30 MeV and current strengths between 30 and 120 μA, and are mostly used for medical and dosage standards.
Synchrotron particle gas pedal
A cyclotron resonant gas pedal that accelerates high-energy particles. It has a large ring magnet. Charged particles are guided and controlled by the ring's magnetic field along a circular or near-circular track of fixed radius, passing through a number of high-frequency accelerating chambers set up along the way to obtain energy from them. During the acceleration process, the magnetic field is enhanced with time so that the radius of the particle's orbit remains constant. The frequency of the high-frequency electric field is synchronized with the magnetic field to maintain resonance with the cyclotron motion of the particles. The gas pedal operates in a pulsed state because the electric and magnetic fields vary periodically with time. Sufficient focusing force is also required in order to confine the particle beam to accelerate in a narrow vacuum chamber. Early on, a constant gradient magnetic field with a small value of gradient was used for focusing. Due to the weak focusing force, the acceleration chamber as well as the whole gas pedal had to be quite large, which economically and technically limited the development of synchrotrons to energies above 10 GeV. Later, the strong focusing method of alternating gradient was invented, and the effective focusing power greatly exceeded the former, so that the size of the acceleration chamber was greatly reduced. For example, a strongly focused 30 GeV proton synchrotron magnet weighs about 4,000 tons, while a constant gradient focus would weigh 100,000 tons.
Electron Synchrotrons Particle Accelerators
Electron cyclotrons or linear gas pedals are typically used as injectors, where electrons are pre-accelerated to near the speed of light and then injected into a synchrotron for further acceleration to a nominal energy. Small electron synchrotron often do not use the injector, it is first in the state of the electron induction gas pedal start, to be pre-accelerated to near the speed of light, open the high-frequency acceleration chamber, so that the particles into the synchronous acceleration to the near-light-speed rotation of the electron its cyclotron frequency does not change with the energy, so the electron synchrotron using a constant-frequency accelerating electric field. Typical electron synchrotron energy of 0.3 ~ 8 GeV, flow intensity of 10pps (particles / sec), beam pulse repetition frequency of 10 ~ 60Hz.
High-speed electron along the circular orbit movement of the electromagnetic radiation emitted by the limitation of the electron synchrotron energy to increase the important factors. Electron energy up to 10 GeV, each turn of the radiation 10 MeV of energy. But this synchrotron radiation has a series of special advantages: that is, the emission of infrared to X-rays can be controlled by the continuity of the spectrum, and the radiation is polarized, high intensity, directionality, and has a high practical value. Has been widely used in solid state physics, molecular biology and integrated circuit development and so on.
Proton Synchrotron Particle Accelerator
Usually, high voltage multipliers and proton linear gas pedals are used as injectors, and protons are pre-accelerated to 20-200 MeV before being injected into the ring orbit of the synchrotron for acceleration. Large synchrotrons often add a smaller fast-pulse synchrotron as an intermediate stage after the injector (also known as the "booster") to accelerate the protons to about 10 GeV, in order to increase the flow intensity of the accelerated particles. Acceleration process, the proton speed in a wide range of changes, the frequency of the electric field must be correspondingly in a wide range of modulation, and need to be precisely controlled, so that it is synchronized with the rise of the magnetic field. For this reason, often set up around the beam current track pickup plate, monitoring the movement of protons, and this signal automatically correct the process of high-frequency electric field frequency modulation. The old strong focusing synchrotron's main magnet using the "composite role" scheme, that is, each magnetic section of both deflection guide and focusing two kinds of roles. This magnet track magnetic field can not be too high, only 1.4T or so, so the amount of iron is larger; new giant synchrotron using the "separation of the role of" program, that is, guidance and focusing by the dipole magnet such as quadrupole lens respectively, the result of the track field strength can be increased to 2T, greatly saving the amount of iron.
To date, there are more than a dozen proton synchrotron gas pedals built internationally, nine of which were built in the 1960s, and the largest one is the 1000 GeV gas pedal at the Fermi National Accelerator Laboratory in the United States.
Heavy ion synchrotron
The structure of the synchrotron is basically the same as that of the proton synchrotron. However, the velocity of heavy ions during acceleration varies over a much wider range than that of protons, so the frequency of the high-frequency electric field also needs to be modulated over a much wider range. On the other hand, because of the long acceleration distance of heavy ions and the large charge exchange cross section with the surrounding gas molecules, the gas pressure in the acceleration chamber is required to be as low as 10 Torr (1 Torr = 133.322 Pa). The earliest use of synchronous acceleration to accelerate high-energy heavy ions is the United States Berkeley Lawrence Laboratory's Bevalek gas pedal. At present it has been able to accelerate N, Ne, Ar, Fe and other heavy ions to more than 2 GeV per nucleon. The flow intensity reaches 10 to 10 pps.
Storage rings and colliders Particle gas pedals
This is a kind of ultra-high-energy experimental device developed on the basis of synchrotron. Previously, particle physics experiments were performed by bombarding a stationary target with relativistic-speed particles. However, in this mode of action, only a small fraction of the energy in the center-of-mass system can be used to produce new particles or meaningful reactions. If the mode of action is changed so that two energetic particle beams moving in opposite directions collide head-on, the effective energy of action will be much higher than in the former mode.
The advantage of a collider is that it can be used to perform ultrahigh-energy experiments with the usual high-energy gas pedals, which are not too expensive. However, it can only realize the collision between stable particles, and can not produce various secondary particle beams like the general gas pedal. Therefore, it is not a substitute for ultrahigh-energy gas pedals. For this reason, the current high-energy physics centers are inclined to develop gas pedal - collider complex, both for a variety of particle collision, but also for static target experiments.
Laser particle gas pedal
Tomas Plettner, an American scientist, reports in a recent issue of Physical Review Letters that he, along with colleagues at Stanford University and the Stanford Linear Accelerator Center (SLAC), have modulated the energy of electrons orbiting in a vacuum with a commercially available laser with a wavelength of 800 nanometers, obtaining the same modulation effect as that obtained with a diminishing 40-million-volt-per-meter electric field. This technique is expected to be developed into a new type of laser particle gas pedal that can be used to accelerate particles to the order of Tev (trillion electron volts).