A mercury-free ultraviolet (UV) discharge source (10) includes an elongated envelope (14) having a diameter in a preferred range from approximately 2 to 3 cm, and thermionically emitting electrodes (16). The envelope contains a rare gas fill (xenon or krypton, including mixtures of these with other rare gases) at a pressure in a range from approx-imately 10 millitorr to approximately 200 millitorr. A power supply (22) is arranged for ionizing the rare gas fill and generating a discharge (12) with a current in a range from approximately 100 to approximately 500 milliamperes (mA). The UV discharge source has an efficiency and output comparable to existing mercury-based low-pressure discharge sources and is intended for use with a suitable phosphor capable of converting the UV radiation to visible light in a fluorescent lamp.