A NEW X-RAY AMPLIFIER PUMPED BY THE KINETIC ENERGY OF CLUSTERS G. W. KENTWELL, H. HORA, J. P. SHEERIN, W. C. STWALLEY and J. C. WANG J. Phys. Colloques, 47 C6 (1986) C6-165-C6-170 DOI: 10.1051/jphyscol:1986623