Physics and modeling of electron emission and injection from low current to high current regime

In this talk, we will present our works in studying the physics of electron emission from cathodes in some new operating regimes: quantum and ultrafast CL law, non-equilibrium model of ultrafast laser excited photon-field emission, quantum shot noise of field emission from sharp emitters. The results cover a wide range of parameters from low current injection limited regime known as Fowler-Nordheim (FN) law to high current space charge limited (SCL) regime known as Child-Langmuir (CL) law. Some insights related the SCL electron flow in free space and solids will also be discussed. The respectively voltage scaling of V^3/2 and V² in CL law and MG law are well-known and important in many areas such as high current cathode (CL law), and organic electronics (MG law). A new scaling between V^3/2 and V² (a combination of CL law and MG law) will be discussed for a system where both CL and MG law become important. The talk is focused on theory and modeling, but some related experimental works will also be discussed briefly. Some novel applications using electron beam will be discussed.