A method and portable device for modifying or coating a surface of turbine components in the field includes an ESD torch electrically connected with ESD equipment. The ESD torch includes an inert gas source, vibration source, and electrode disk of conductive material. The electrode disk is disposed within the ESD torch, shielded by an inert gas and coupled with the vibration source. The electrode disk is rolled over the surface, which actuates the electrode disk and deposits the conductive material from the electrode disk onto the surface of the workpiece to form the compositionally controlled protective coating. The compositionally controlled protective coating deposited by the electrode disk forms a metallurgical bond with the surface of the workpiece to prevent erosion of the workpiece.