A Bose-Einstein condensate was produced in a vapor of rubidium-87 atoms that was confined by magnetic fields and evaporatively cooled. The condensate fraction first appeared near a temperature of 170 nanokelvin and a number density of 2.5 x 1012 per cubic centimeter and could be preserved for more than 15 seconds. Three primary signatures of Bose-Einstein condensation were seen. (i) On top of a broad thermal velocity distribution, a narrow peak appeared that was centered at zero velocity. (ii) The fraction of the atoms that were in this low-velocity peak increased abruptly as the sample temperature was lowered. (iii) The Fig. 1. The optical components and magnetic coils are all located outside the ultrahigh-vacuum glass cell, which allows for easy access and modification. Rubidium atoms from the background vapor were optically precooled and trapped, loaded into a magnetic trap, then further cooled by evaporation. The TOP (time orbiting potential) magnetic trap (13) we used is a superposition of a large spherical quadrupole field and a small uniform transverse field that rotates at 7.5 kHz. This arrangement results in an effective average potential that is an axially symmetric, three-dimensional (3D) harmonic potential providing tight and stable confinement during evaporation. The evaporative cooling works by selectively re-

We describe a new type of magnetic trap whose time-averaged, orbiting potential (TOP) supplies tight and harmonic confinement of atoms. The TOP trap allows for long storage times even for cold atom samples by suppressing the loss due to nonadiabatic spin Hips which limits the storage time in an ordinary magnetic quadrupole trap. In preliminary experiments on evaporative cooling of ' Rb atoms in the TOP trap, we obtain a phase-space density enhancement of up to 3 orders of magnitude and temperatures as low as 200 nK. PACS numbers: 32.80.Pj, 42.50.Vk, 85.70.Nk Laser cooling and trapping of neutral atoms can provide up to 15 orders of magnitude phase-space density compression in alkali vapors [I]; however, optical processes limiting density [2] and temperature [3] have obstructed efforts to optically cool an atom sample directly to the Bose-Einstein condensation (BEC) phase transition. Evaporative cooling [4] in a purely magnetic trap offers an appealing, nonoptical cooling mechanism that can enhance the phase-space density of an optically precooled sample by orders of magnitude [5]. The resulting atom