The experimental observation of the self$-$excited dust acoustic waves (DAWs)and its propagation characteristics in the absence and presence of a floatingcylindrical object are investigated. The experiments are carried out in adirect current (DC) glow discharge dusty plasma in the background of argon gas.Dust particles are found levitated at the interface of plasma and cathodesheath region. The DAWs are spontaneously excited in the dust medium and foundto propagate in the direction of ion drift (along the gravity) above athreshold discharge current at lower pressure. The excitation of such lowfrequency wave is a result of the ion--dust streaming instability in the dustcloud. The characteristics of the propagating dust acoustic wave get modifiedin presence of a floating cylindrical object of radius larger than the dustDebye length. Instead of propagating in the vertical direction, the DAWs arefound to propagate obliquely in presence of the floating object (kept eithervertically or horizontally). In addition, horizontally aligned floating objectgives rise to form a wave structure in the cone shaped dust cloud in the sheathregion. The change in the propagation characteristics of DAWs are explained onthe basis of modified potential (or electric field) distribution, which is aconsequence of coupling of sheaths formed around the cylindrical object and thecathode.
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