Study of the effect of pyrex and quartz insulators on X-ray intensity in a 4 kJ plasma focus device Saeedeh Koohestani, Morteza Habibi and Reza Amrollahi Eur. Phys. J. D, 67 6 (2013) 128 Published online: 27 June 2013 DOI: 10.1140/epjd/e2013-30769-2