A system for extracting tissue from a working space in a patient's body, said system comprising: an elongate shaft assembly comprising: an outer sleeve having a tissue-receiving window near a distal end thereof, an inner insulative layer, and a distal tip, wherein a distal chamber is defined by the outer sleeve and the distal tip and is configured to capture a liquid volume from the working space; an inner sleeve accommodated within a lumen of the outer sleeve and configured to reciprocate in the lumen of the outer sleeve, the distal end of inner sleeve comprising a first polarity electrode with a distal cutting electrode edge, said inner sleeve further comprising a tissue extraction lumen, and an exterior insulative layer; wherein exposed surfaces of the outer sleeve comprise a second polarity electrode; and an RF source connectable to the first polarity electrode and the second polarity electrode; wherein the system is configured to operate in first and second electrosurgical modes, wherein in a first mode, the first polarity electrode acts as an active electrode to focus energy about the electrode edge to generate plasma for tissue cutting and the second polarity electrode acts as the return electrode, wherein the system is configured to operate in the first mode when the inner sleeve is distally advanced past the tissue-receiving window to cut tissue protruding through the tissue-receiving window and to capture the cut tissue in the tissue extraction lumen of the inner sleeve; wherein the system is configured to switch to the second mode when the inner sleeve entirely crosses the tissue-receiving window, wherein in the a second mode, the electrode edge is confined within the chamber and the system is configured such that an interior surface area of the distal tip interfacing the chamber functions as an active electrode and a distal end portion of the inner sleeve exposed to the chamber acts as a return electrode, wherein applying RF energy between the active electrode and the return electrode causes a rapid vaporization of the captured liquid volume to propel the cut tissue proximally through the tissue extraction lumen. an outer sleeve having a tissue-receiving window near a distal end thereof, an inner insulative layer, and a distal tip, wherein a distal chamber is defined by the outer sleeve and the distal tip and is configured to capture a liquid volume from the working space; an inner sleeve accommodated within a lumen of the outer sleeve and configured to reciprocate in the lumen of the outer sleeve, the distal end of inner sleeve comprising a first polarity electrode with a distal cutting electrode edge, said inner sleeve further comprising a tissue extraction lumen, and an exterior insulative layer; wherein exposed surfaces of the outer sleeve comprise a second polarity electrode; and an RF source connectable to the first polarity electrode and the second polarity electrode; wherein the system is configured to operate in first and second electrosurgical modes, wherein in a first mode, the first polarity electrode acts as an active electrode to focus energy about the electrode edge to generate plasma for tissue cutting and the second polarity electrode acts as the return electrode, wherein the system is configured to operate in the first mode when the inner sleeve is distally advanced past the tissue-receiving window to cut tissue protruding through the tissue-receiving window and to capture the cut tissue in the tissue extraction lumen of the inner sleeve; wherein the system is configured to switch to the second mode when the inner sleeve entirely crosses the tissue-receiving window, wherein in the a second mode, the electrode edge is confined within the chamber and the system is configured such that an interior surface area of the distal tip interfacing the chamber functions as an active electrode and a distal end portion of the inner sleeve exposed to the chamber acts as a return electrode, wherein applying RF energy between the active electrode and the return electrode causes a rapid vaporization of the captured liquid volume to propel the cut tissue proximally through the tissue extraction lumen. a tissue extraction lumen, and an exterior insulative layer; wherein exposed surfaces of the outer sleeve comprise a second polarity electrode; and an RF source connectable to the first polarity electrode and the second polarity electrode; wherein the system is configured to operate in first and second electrosurgical modes, wherein in a first mode, the first polarity electrode acts as an active electrode to focus energy about the electrode edge to generate plasma for tissue cutting and the second polarity electrode acts as the return electrode, wherein the system is configured to operate in the first mode when the inner sleeve is distally advanced past the tissue-receiving window to cut tissue protruding through the tissue-receiving window and to capture the cut tissue in the tissue extraction lumen of the inner sleeve; wherein the system is configured to switch to the second mode when the inner sleeve entirely crosses the tissue-receiving window, wherein in the a second mode, the electrode edge is confined within the chamber and the system is configured such that an interior surface area of the distal tip interfacing the chamber functions as an active electrode and a distal end portion of the inner sleeve exposed to the chamber acts as a return electrode, wherein applying RF energy between the active electrode and the return electrode causes a rapid vaporization of the captured liquid volume to propel the cut tissue proximally through the tissue extraction lumen.