پديد آورنده :
فروتن، الهام
عنوان :
بررسي اثر ميدان و طول لوله رانش برعبور يونها
مقطع تحصيلي :
كارشناسي ارشد
گرايش تحصيلي :
شيمي فيزيك
محل تحصيل :
اصفهان: دانشگاه صنعتي اصفهان، دانشكده شيمي
صفحه شمار :
يازده، 59، [II]ص.: مصور، نمودار
يادداشت :
ص. ع. به: فارسي وانگليسي
استاد راهنما :
محمود تبريز چي
توصيفگر ها :
كلكتور , دستگاهوري
تاريخ نمايه سازي :
23/07/1387
استاد داور :
بيژن نجفي، عذرا عابدي
تاريخ ورود اطلاعات :
1396/08/30
چكيده فارسي :
به فارسي وانگليسي: قابل رويت در نسخه ديجيتال
چكيده انگليسي :
Abstract Drift tube is the most important part in ion mobility spectrometer It is usuallycomposed of several successive conductive and insulator rings The adjacent conductiverings are connected to each other by a resistor A potential difference is applied betweenthe two ends of the drift tube to create a homogeneous electric field inside the tube Ions produced by ionization source pass through the drift tube to reach collector Most ions areannihilated during their drift towards the collector Any improvement on transmission ofions through drift tube results in considerable enhancement in ion signal intensity The ionlost and its mechanism is not well understood The aim of this work is to study andcharacterize the ion lost due to length of drift tube and the electric field The results showthat increasing the drift field enhances the collector current quadraticly It was also shownthat the ion current decreases with the drift tube length A simple model based on kineticsof two parallel processes loss or transmission is proposed to explain the results In thismodel it is assumed that the ion lost rate is proportional to the ion density and the iontransmission rate is proportional to the ion velocity as well as the ion density The collectorcurrent IC is then described by k d u IC Io k L k d u Where Io is the initial current delivered at the entrance of the drift tube u is the velocityof ion and kd and kL are the ion lost and ion transmission rate constant respectively kd andkL are constants which depends solely on the geometry of drift tube All the observedresults are in good agreement with the predicted behavior by the model The ratio kL kdwhich is a measure of ion lost was assumed to be dependent on d the drift tube length Then the above equation was rearranged to 1 1 1 d IC Io u Where is a new constant depending on geometry of drift tube This equation predictsthat 1 Io is linearly proportional to the drift length with an intercept of 1 Io The observedresults well agree with this prediction In addition it was proved that Io is linearlyproportional to the applied electric field strength It is thought that ions are mainly lost due to collision with wall This is due totransversal expansion of ions moving through the drift tube An experiment was performedto measure the radial distribution of ions at different distances from the ion source Theresult which is a 3 D image of the ion distribution in the drift tube relates that the ionsbecome broader as the ion cloud travels As a result they hit the walls of the drift tube andare annihilated The results obtained are used in designing drift tubes for specialapplications
استاد راهنما :
محمود تبريز چي
استاد داور :
بيژن نجفي، عذرا عابدي
