In this paper we report the results of Micromegas prototypes constructed by attaching micromesh to an anode using thermo-bond films. The excellent metal attaching ability and good dielectical property of this kind of film make it a promising material to be used as avalanche gap spacers. Several prototypes are successfully made. The electron transmission properties are first studied and then the gas gain is measured in argon-isobutane mixtures. The maximum gain of more than 104 is easily obtained. The energy resolutions for 55Fe 5.9 keV K~ ray can be better than 20% over one magnitude in gain for different operational gas mixtures and the best energy resolution of 13.7% （FWHM） can be achieved with the gas mixture of 94% argon concentration. The preliminary test results of the prototypes with sensitive area of 45 mm×45 mm without internal support show good uniformity across the sensitive area.
The structure and working principle of Micromegas （MICRO Mesh Gaseous Structure） is discussed. Some radiation sources of α and X rays are used to test this detector. The optimized electric-field intensity of the conversion gap is obtained. The transmission of electrons and the uniformity of the amplification gap are also presented. The energy resolution of the 5.9 keV peak is better than 27%.
Micromegas （MICRO MEsh GAseous Structure） is a position-sensitive gaseous detector. It is widely used in particle physics. We present the results of full 3D Monte Carlo simulations of Micromegas performance, taking into account all the processes from the primary ionization, the elctron collection efficiency, and the gain to the signal formation. The simulation results are in good agreement with experimental data.
