can u please elaborate what u wanna say

I do not fuly understand your question, but think that you are referring to using plasma to preclean the substrate prior to the deposition of films. In this particular circumstance, Ar, H2, O2 or Ar/O2, etc discharges are used  to eliminate contamination (C-based, Oxides) from substrate surfaces via surface physical or chemical etching in order to improve the adhesion between the substrate and the subsequent layers (also most often deposited using plasma). If this does not answer your question, please feel free to add more details, and I will try to better my answer.

I am assuming that, you are doing experiments on thin film deposition using plasma. You have to take extra care (mechanical cleaning and touch with only hand gloves) of substrates before inserting inside the vacuum chamber. Then high vacuum (low base pressure) should be attained, so  H2, O2 and N2 and CO can be removed from the chamber. If these particles would be present inside the chamber, some problems can encountered, like surface contamination, including loss of film adhesion, poor optical properties, and contact resistance issues. Then you can achieve your working pressure by desired gas.

If by high vacuum, you think substrates are not enough clean, then substrates can be cleaned by dc/rf plasma cleaning.

Actually my question is not related to film deposition but while creating plasma initially in a device there was arcing at some point and discharge current was not constant so I want to know is this happens initially or get stabilized after few itiration. yes pressure is low.     

Depending on the plasma generator, the arching easily occurs. If you are discharging in the system, heater and plate. The discharge easily happens and the plasma is not stable. At least you should put a resistance to the plate. When it arcs, the voltage drop of the resistance  reduces the plate voltage. The resistor  works as a automatic controller of the discharge current.

We use a different type of plasma generator which has been invented long  time ago,  by Pro Takayama. The generator consists of heater (electron emitter), and a grid mesh which accelerate electrons to ionize neutral particles, and then plate. The plasma generator provide plasma which is very similar ionosphere plasma(Te 1000-3000K,Ne 103ele/cc-105 els/cc).  Are these information which you wanted.

by the way to clean f the metal surface , chemical cleaning  does not work at all.

ion bombardment of the electrode n plasma works when back ground neutral pressure is low.  Most effective way of the electrode cleaning is to heat the electrode above 100C.  Main contaminant is water, and the thickness of the contaminant is about 20-80 nm.

I hope i answered to your questions.

Normally arcing happens for high frequency plasma (RF and microwave). If the electrode (for both DC and RF) is contaminated, initially for 10-20 minutes arcings will occur and stabilized. you have to mention your exact conditions and type of plasma production.

Its a DC discharge plasma and yes after few iteration of plasma production it got stabilize.

Thank you all for answering.

"Plasma cleaning" of surface typically means the eliminating of contaminations (diel. films, gas layers etc) by ion bombardment

It can be done e.g. by glow discharge (high voltage, low current), and it depends on the kind of contaminations

If there are contaminations it is more easy to ignite erosive - vacuum arc discharge (large current, low voltage), which operates by a cathode spots with micron-size cells that explosively produce a plasma and current (ns) pulses.

Cathode spots of "1st type" - burning at a contaminated surface (small separate craters), and CS of "2nd type" - burning at a clean surface (large overlapping craters)

G. A. Mesyats and D. I. Proskurovsky 1989 Pulsed Electrical Discharge in Vacuum (Berlin: Springer Verlag)

A. Anders 2008 Cathodic Arcs. From Fractal Spots to Energetic Condensation (Springer Science + Business Media, LLC, New York, NY)

G. A. Mesyats 2013 IEEE Trans. Plasma Sci. 41 676-694

André Anders, 2014 Surface and Coatings Technology 257 308-325

It is interesting to read comments from various experienced people.

I'd like to add information here regarding those who are interesting in glow discharge plasmas.

In glow discharge spectrometry analysis, often we called it as “pre-burning the sample” which simply means igniting the discharge, and waiting before integrating the spectral intensities. The purpose of pre-burning is to removes oils, oxide films, and other contaminants from the sample surface. For routine analysis, practice of pre-burning the sample is quite helpful to remove vapours, oxide, like water, from the discharge cavity by destroying their molecular structure. The result is improved RSD for calibration and bulk analysis measurements. In low pressure glow discharges, typical pre-burn times are between 30 seconds and 90 seconds. This corresponds to a sputtered depth of about 5 to 10 micro-meter.

For more detailed studies, I would refer a very useful book to all young researchers

“Practical Guide to Glow Discharge Optical Emission Spectroscopy”

By Thomas Nelis and Richard Payling

I hope your DC power supply is already equipped with good arc quenching circuit.

DC power supply with good arc quenching circuit can reduce lots of arc and less surface damage for your workpiece.