  Generation and amplification of magnetic fields in plasmas is a long-standing
topic that is of great interest to both plasma and space physics. The electron
Weibel instability is a well-known mechanism responsible for self-generating
magnetic fields in plasmas with temperature anisotropy and has been extensively
investigated in both theory and simulations, yet experimental verification of
this instability has been challenging. Recently, we demonstrated a new
experimental platform that enables the controlled initialization of highly
nonthermal and/or anisotropic plasma electron velocity distributions via
optical-field ionization. Using an external electron probe bunch from a linear
accelerator, the onset, saturation and decay of the self-generated magnetic
fields due to electron Weibel instability were measured for the first time to
our knowledge. In this paper, we will first present experimental results on
time-resolved measurements of the Weibel magnetic fields in non-relativistic
plasmas produced by Ti:Sapphire laser pulses (0.8 $\mu m$) and then discuss the
feasibility of extending the study to quasi-relativistic regime by using
intense $\rm CO_2$ (e.g., 9.2 $\mu m$) lasers to produce much hotter plasmas.
