the measured values. As shown in the Fig. 4(inset), this difference can be attributed to an experimental increase in r 0 ∼ ω − 2 / 3 x due to the measured decrease of ω$_{x}$ with α $^{2}$. This implies that the average particle charge q is effectively constant, as previously observed for constant neutral pressure [8, 19]. This increase in r 0 with α 2 is not as apparent for y$_{rms}$ since y$_{rms}$ ≲ 0 . 2 x$_{rms}$ and y$_{rms}$ → 0 as α 2 increases. In summary, we have provided direct evidence that the width of a Yukawa cluster exhibits power law behavior for the 1D to 2D zigzag transition caused by decreasing the confining well anisotropy parameter α $^{2}$, confirming a previous prediction [16]. Experiments were performed using a dusty plasma with n = 6 particles confined in the biharmonic well above a rectangular depression. The width d of the rectangular depression was increased while the plasma remained on to decrease α 2 while the Debye shielding parameter κ remained essentially constant. The dependence of α 2 on d was accurately determined by measuring the c.m. frequencies of the dusty plasma. A transition from the zigzag configuration to an elliptical configuration was also observed. The cluster width was found to be in excellent agreement with the predictions of a model which assumes identical particles confined in a 2D biharmonic well and interacting through a Yukawa potential. From the fit to the model we found the Debye length is comparable to the inter-particle distance, so that Debye shielding significantly effects the physics of these clusters. Portions of this paper are taken from A. L. M.’s undergraduate physics thesis. Acknowledgments [1] F. F. Chen, Introduction to Plasma Physics (Plenum, New York, 1974), p. 3. [2] M. Lampe, G. Joyce, G. Ganguli and V. Gavrishchaka, Phys. Plasmas 7 , 3851 (2000). [3] A. Homann, A. Melzer, S. Peters and A. Piel, Phys. Rev. E 56 , 7138 (1997). [4] T. Misawa, N. Ohno, K. Asano, M. Sawai, S. Takamura and P. K. Kaw, Phys. Rev. Lett. 86 , 1219 (2001). [5] B. Liu and J. Goree, Phys. Rev. E 71 , 046410 (2005). [6] W.-T. Juan, Z.-H. Huang, J.-W. Hsu, Y.-J. Lai and L. I, Phys. Rev. E 58 , R6947 (1998). [7] T. E. Sheridan, J. Phys. D: Appl. Phys 39 , 693 (2006). 10