Associate Professor Mara Prentiss yesterday became second woman in the history of the physics department to receive tenure from that department.

The significance of the appointment to the department was twofold, according to Gary J. Feldman, chair of the physics department. "We've been working very hard to make it a comfortable place for female students," Feldman said.

Feldman said the appointment represented a larger trend of increasing female students in the graduate Physics program. "We have an usually large number of female graduate students," he said.

The appointment is in keeping with the physics department's efforts to promote its junior faculty, Feldman said.

Whenever possible, the department hires the strongest junior faculty members available, Feldman said. As a result, when the department seeks to offer tenure to top physicists in any particular field, it frequently finds that individual is already a member of the Department, he said.

"[Prentiss] was judged to be the top in her peer group," Feldman said.

As an experimental atomic physicist, Prentiss specializes in using laser fields to manipulate atoms, he said.

Prentiss's work is significant, Feldman said, because she has performed research on electromagnetic fields. The knowledge she has gained by depositing atoms in narrow lines could have important applications in lithography, he said.

According to Feldman, Prentiss, the 1994 recipient of the Phi Betta Kappa Award for excellence in teaching, has also obtained a patent to place a lens on a optical filter.

"It's still unreal," Prentiss said. I'was jumping up and down walking through Harvard Square."

Students and faculty in the department said they were surprised at the pace of the process. "We didn't realize it could be this quickly," said J.D. Paul, a physics graduate student.

Physics professors said yesterday that Prentiss is extremely well qualified and will prove a valuable addition to the Harvard faculty.

"There was no question," said Melissa Franklin, professor of physics, who is the only other tenured female professor in the department.

"It's great," she said. We're taking over."