Thermo-field form changes of the alloy Hf-W and adsorbed layers of Hf on W

摘要

The simultaneously action of high electric fields F and high temperatures T on the tips from alloys Hf-W and adsorbed layers of Hf on W was studied by means of field emission microscopy. It is known that Hf is a very emission active adsorbate lowering essentially the work function Φ of W-surface. Beside that a coverage Hf on W localizes the electron emission in the regions {001} in small corporal angles by means of surface migration even without the presence of high electric field [1]. These properties of Hf-coverage on w enable to produce the effective field emission cathodes with high local current density like to Zr-W cathodes [2,3]. The thermo-field treatment of thee coverages may give a ossibility to improve the angular confinement of an electron emission. In the process of a thermo-field treatment it should be distinguished the field of a treatment F_(tr), which is determined with respect to initial annealed tip form and a final field F_(fin), which is determined after thermo-field treatment. The values of F_(fin) are always significantly more in comparison with F_(tr) as a result of a rise of the field factor β after the thermo-field treatment of the emitter.