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We observed the ultra-compact binary candidate 4U 0614+091 for a total of 200ksec with the high-energy transmission gratings onboard the \chandra X-rayObservatory. The source is found at various intensity levels with spectralvariations present. X-ray luminosities vary between 2.0$\times10^{36}$ \ergsecand 3.5$\times10^{36}$ \ergsec. Continuum variations are present at all timesand spectra can be well fit with a powerlaw component, a high kT blackbodycomponent, and a broad line component near oxygen. The spectra requireadjustments to the Ne K edge and in some occasions also to the Mg K edge. TheNe K edge appears variable in terms of optical depths and morphology. The edgereveals average blue- and red-shifted values implying Doppler velocities of theorder of 3500 \kms. The data show that Ne K exhibits excess column densities ofup to several 10$^{18}$ cm$^{-2}$. The variability proves that the excess isintrinsic to the source. The correponding disk velocities also imply an outerdisk radius of the order of $< 10^9$ cm consistent with an ultra-compact binarynature. We also detect a prominent soft emission line complex near the \oviiiL$\alpha$ position which appears extremely broad and relativistic effects fromnear the innermost disk have to be included. Gravitationally broadened linefits also provide nearly edge-on angles of inclination between 86 and89$^{\circ}$. The emissions appear consistent with an ionized disk withionization parameters of the order of 10$^4$ at radii of a few 10$^7$ cm. Theline wavelengths with respect to \oviiia\ are found variably blue-shiftedindicating more complex inner disk dynamics.

Dynamical Ne K Edge and Line Variations in the X-Ray Spectrum of the Ultra-compact Binary 4U 0614+091