Two-dimensional gas
（重定向自Two dimensional gas）
![](/Images/godic/202502/18/Elastischer_stoß_2D3800.gif")
![Diagram of cyclotron operation from Lawrence's 1934 patent.](/Images/godic/202502/18/Cyclotron_patent3800.png")
A two-dimensional gas is a collection of objects constrained to move in a planar or other two-dimensional space in a gaseous state. The objects can be: ideal gas elements such as rigid disks undergoing elastic collisions; elementary particles, or any object in physics which obeys laws of motion. The concept of a two-dimensional gas is used either because: