Langmuir probe measurements of electron density and electron temperature in early stage of laser-produced carbon plasma

Langmuir probe measurements of electron density, electron temperature and potential are mad in the early stage (<5${\mu}$s) of a laser ablated plasma plume, in which a positive current form positive ions and a electron current are overlapped. The plasma wes produced by focusing the second harmonic, 532 nm, of Q-switched Nd:YAG laser on a high purity carbon target. Then the laser intensity on the target of ~1.6${\times}$10$\^$15/ W/$\textrm{cm}^2$. The measured electron desities and temperatures are ~2${\times}$10/sip 11/ cm$\^$-3/ and -3 eV. In particluar , the phenomenon that the electron temperature decreased and then increased was observed,. It could be well explained that this phenomenon occurred in the process of inverse Bremsstrahlung of free electrons in plasma. Additionally, the plasma potential(>11V) was higher than the published values.