Yes! If you are a project leader, there are two approaches for designating TAs in your project.
Using manager privileges
The simplest approach is to set the privileges for your TAs to manager when you approve their accounts. You can also change the privileges on a user that is already a member of your project.
Managers are allowed to approve new users to the project or subgroup, as well as set the privileges for other members of the project. Typically class TAs would be given this permission so that they can help the instructor manage the class.
Using subgroups for groups of students.
Another approach is to create a project subgroup for small groups of students, with a TA as the leader of the group. A project group is a lot like a unix group, and in fact unix groups is the mechanism used to protect members of one group from members of another group. When you create a group, you designate a group leader who is responsible for approving users who apply to join the group. Group leaders may also terminate experiments that have been created by members of the group.
As project Leader, you may also shift members of your project in and out of your project's groups as you like, and you are automatically a member of all groups within your project.
To create (and edit) project groups, click on the Membership tab on your dashboard page, then click on the project you want to manage. On the Project page, click on the Groups tab. You can edit existing groups, or create a new group.