Experimental Study of a Plasma Fiber for High Intensity Laser-Plasma Interaction

Summary form only given. A fully ionized "plasma fiber" is able to guide laser pulses with intensities greater than ~10¹⁷ W/cm ². At UCLA, we are developing a hydrogen capillary discharge to form a plasma fiber with a parabolic plasma density profile; i.e., a profile suitable for guiding laser beams of small spot size and high intensity. Our initial experiments use a 500 mum diameter, 5 mm long capillary producing an on axis density of about 5times10¹⁸ cm^-3. By sending a low-power laser beam through the plasma channel and measuring the evolution of the spot size within and beyond the capillary, we determine the second derivative of the density parabola and its dependence on time and plasma-heating current. In addition to the laser propagation study, we use time-, space-, and spectrally-resolved line/continuum emission to study the plasma properties over the ~300 ns current pulse (up to 300 A). We intend to use these results to assist in the design and optimization of our next generation, smaller diameter and longer capillary discharge to guide a smaller spot-size laser beam over a longer distance