An emissive material for use in a vapor discharge device including reacted Ba.sub.x Sr.sub.1-x Y.sub.2 O.sub.4 wherein X satisfies the following: 1>X.gtoreq.0. A vapor discharge device is provided having an arc tube which includes electrodes therein coated with such emissive material.

A method and apparatus is presented for planarizing or polishing workpiece surfaces using an ion beam in the presence of a radio frequency generated plasma. A workpiece is placed in a holder within a vacuum chamber equipped with a radio frequency inductive plasma generator. The workpiece surface is exposed to a source of energetic ions, the chamber is filled with gas, and the gas is ionized with radio frequency energy to form inductive plasma that surrounds the workpiece. An ion beam mounted above the workpiece scans the workpiece surface with sufficient energy to remove micro irregularities from the workpiece surface.

When a charged beam is irradiated on a sample, charge up of electric charge of the same polarity as that of the charged beam is built up on the sample surface. In order to neutralize the charge up electric charge, an apparatus for suppressing electrification of sample in charged beam irradiation apparatus is provided in which electric charge of opposite polarity to that of the charged beam is generated near the sample surface to neutralize the charged beam or charge up electric charge on the sample surface. The electric charge for neutralization is generated by admitting elecrtic charge from a plasma generation unit to the vicinity of the sample surface, ionizing gas generated from the sample surface by causing the charged beam to collide the gas or by irradiating electrons from an electron source on the sample surface. Especially when there is a possibility that impurities other than the electric charge for neutralization affect the sample adversely, an impurity generation source is blind folded with a cover so as not to be seen through from the sample and charged beam so that the impurities may be prevented from impinging upon the sample surface or intersecting the charged beam path.

A plasma flood system for use in the implantation of ions in a semiconductor substrate comprising a plasma and low energy electron source for developing a plasma containing low energy electrons for magnetic field enhanced transmission to a negatively biased, magnetic field assisted electron confinement tube and into an ion beam flowing axially through the tube to the semiconductor substrate for self regulating and neutralizing positive charges on the surface of the substrate without causing significant negative charging of the substrate.

When a charged beam is irradiated on a sample, charge up of electric charge of the same polarity as that of the charged beam is built up on the sample surface. In order to neutralize the charge up electric charge, an apparatus for suppressing electrification of sample in charged beam irradiation apparatus is provided in which electric charge of opposite polarity to that of the charged beam is generated near the sample surface to neutralize the charged beam or charge up electric charge on the sample surface. The electric charge for neutralization is generated by admitting elecrtic charge from a plasma generation unit to the vicinity of the sample surface, ionizing gas generated from the sample surface by causing the charged beam to collide the gas or by irradiating electrons from an electron source on the sample surface. Especially when there is a possibility that impurities other than the electric charge for neutralization affect the sample adversely, an impurity generation source is blind folded with a cover so as not to be seen through from the sample and charged beam so that the impurities may be prevented from impinging upon the sample surface or intersecting the charged beam path.