Low Density Plasma Waveguides Driven by Ultrashort (30 fs) and Long (300 ps) Pulses for Laser Wakefield Acceleration

We simulate the possibility of scaling channel formation to low densities plasmas of low atomic number gas over a large range of pulse duration including (1) pulses up to 300 ps in duration, using inverse bremsstrahlung (IB) heating and (2) ultrashort pulses up to 100s of femtoseconds for generating tenuous plasmas of centimeter to meter lengths by optical field ionization (OFI) [1]. Results show IB heating up to tens of eV, and channels formed from an initial density of 1×10
¹⁸
cm
^-3
with axial densities as low as 1×10
¹⁷
cm
^-3
, and radius of 50 μm. It has been shown that centimeter-scale waveguides can be generated via OFI heating at densities of approximately 1×10
¹⁷
cm
^-3
[2]; we show calculations and theory of this channel formation using an axicon. Lastly, we outline the experimental setup to be used in future experiments at the University of Texas Tabletop Terawatt (UT3) facility.