Why Spark occurs inside Samsung Microwave oven?

There is no such electronic part inside the cavity which may spark. If grill mode is used for roasting ,food particles remain inside the cavity which gets charged when Microwave oven is used again. This seems to be like sparking inside the cavity.

Corrective actions to take:

a). Clean the cavity properly.

b). You can also steam clean it.Below is the procedure of how to steam clean the cavity:

      ii)  Add lemon juice(2 table spoon) to it.

     iii) Keep it for 15 minutes at microwave mode.

     iv) When steam is generated, wipe cavity properly with clean cloth.

Note: This process may also help in  enhancing  the heating effect.Repeat the process atleast once in a month.