Ejs Open Source Cyclotron Java Applet in 3D
this is my attempt at the assignment given for the construction of Cyclotron
http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=1972.0 which is a derived work from
http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=1450msg5484;topicseen#msg5484 Created by prof Hwang
I thank Prof Hwang for his valuable help in supporting my learning  

/htdocs/ntnujava/ejsuser/14019/users/sgeducation/lookang/chargeinNScyclotron_pkg/chargeinNScyclotron.propertiesFull screen applet or Problem viewing java?Add http://www.phy.ntnu.edu.tw/ to exception site list
Press the Alt key and the left mouse button to drag the applet off the browser and onto the desktop. This work is licensed under a Creative Commons Attribution 2.5 Taiwan License
Download EJS jar file(1643.6kB):double click downloaded file to run it. (102 times by 58 users) , Download EJS source View EJS source

reference: http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/cyclot.html
The cyclotron was one of the earliest types of particle accelerators, and is still used as the first stage of some large multi-stage particle accelerators. It makes use of the magnetic field Bz on a moving charge to bend moving charges into a semicircular path between accelerations by an applied electric field Ey. The applied electric field Ey accelerates charged particles between the "gaps" of the 2 magnetic field region as shown. The electric field Ey is reversed at the cyclotron frequency to accelerate the electrons back across the gap.

How the cyclotron works? http://en.wikipedia.org/wiki/Cyclotron and http://webphysics.davidson.edu/physlet_resources/bu_semester2/c13_cyclotron.html
The charged particles, injected near the center of the magnetic field Bz, accelerate only when passing through the gap between the electric field Ey electrodes with increase in kinetic energy. The perpendicular magnetic field Bz bends moving charges into a semicircular path between the magnets with no increase in kinetic energy. The magnetic field causes the charge to follow a half-circle that carries it back to the gap. While the charge is in the gap the electric field Ey is reversed, so the charge is once again accelerated across the gap. The cycle continues with the magnetic field in the dees continually bringing the charge back to the gap. Every time the charge crosses the gap it picks up speed. This causes the half-circles in the dees to increase in radius, and eventually the charge emerges from the cyclotron at high speed.
The combined motion is a result of increasing energy of the particles in electric field Ey and the magnetic field Bz forces the particles to travel in an increasing radius of the circle after each entry into the other magnetic field. This results in a spiral path of which the particles than emerged at a higher speed than when it was injected into the center of the magnetic field Bz.

Uses of the cyclotron http://en.wikipedia.org/wiki/Cyclotron
For several decades, cyclotrons were the best source of high-energy beams for nuclear physics experiments; several cyclotrons are still in use for this type of research.
Cyclotrons can be used to treat cancer. Ion beams from cyclotrons can be used, as in proton therapy, to penetrate the body and kill tumors by radiation damage, while minimizing damage to healthy tissue along their path.

Problems solved by the cyclotron http://en.wikipedia.org/wiki/Cyclotron
The cyclotron was an improvement over the linear accelerators
Cyclotrons accelerate particles in a spiral path. Therefore, a compact accelerator can contain much more distance than a linear accelerator, with more opportunities to accelerate the particles.

Advantages of the cyclotron http://en.wikipedia.org/wiki/Cyclotron
Cyclotrons produce a continuous stream of particles at the target, so the average power is relatively high.
The compactness of the device reduces other costs, such as its foundations, radiation shielding, and the enclosing building.