在钨惰性气体和金属惰性气体工艺的早期，主要工作是获得电弧及其用途的基本知识。重点介绍了仪器、保护气体、填充丝和焊接条件的发展。随着这些过程从其基本形式发展而来，产生的问题与这些相同的因素有关。由于不了解电源响应对电弧的影响，设计用于带焊条焊接的电源最初用于TIG和MIG工艺。 随着人们对这些焊接新领域的了解，很明显电源也会对结果产生显著影响。在过去的十年里，人们对电源特性的兴趣和知识迅速增长。 在TIG焊接的情况下，问题没有那么复杂，因此现在已经开发出了令人满意的电源。然而，在MIG焊接的情况下，问题更加复杂。这一过程的电源仍在开发中。本报告针对MIG电源，尽管在本报告的前几部分中提到了TIG电源。

During the early years of the tungsten inert-gas and metallic inert-gas processes the main effort was aimed at gaining basic knowledge of the arc and its uses. Emphasis was placed on the development of apparatus, shielding gases, filler wires and welding conditions. As these processes grew from their basic forms the troubles which arose were associated with these same factors. Due to a lack of knowledge of the effect of power supply response on the arc, power supplies designed for welding with covered electrodes were originally used for the TIG and MIG processes. As knowledge was gained in these new fields of welding, it became obvious that the power supply could also have a marked effect on the results. In the last decade interest in, and knowledge of, power supply characteristics has grown rapidly. The problems were not as complex in the case of TIG welding and as a result satisfactory power supplies have now been developed. In the case of MIG welding, however, the problem is more complex. Power supplies for this process are still under development. This report is aimed at the MIG power supply although some reference is made to the TIG power supply in the earlier parts of the report.