Welding thermoplastic structures

1. An apparatus comprising:

a base formed of a material that is magnetically opaque to a frequency in a range of 30 KHz to 350 KHz;

a cover formed of the material;

a channel for magnetic flux extending between the base and the cover;

wherein the base and the cover are configured to contain a structure and the channel is configured to block the magnetic flux from encountering a portion of the structure in a direction non-parallel to the portion of the structure; and

a tool comprising:

a plurality of dies that define a die cavity and a plurality of induction coils, wherein sections of the plurality of induction coils are embedded in the plurality of dies, and wherein the base and the cover are positioned in the die cavity.

2. The apparatus of claim 1 , wherein the base includes a cavity.

3. The apparatus of claim 2 , wherein the cover includes a protrusion extending into the cavity.

4. The apparatus of claim 2 further comprising: an insert formed of the material and positioned in the cavity.

5. The apparatus of claim 4 further comprising: a pressure applicator positioned between the insert and the base.

6. An apparatus comprising:

a tool comprising:

a plurality of dies that define a die cavity and a plurality of induction coils, wherein sections of the plurality of induction coils are embedded in the plurality of dies; and

a flux director positioned within the die cavity;

wherein the flux director comprises a base, a cover, and a channel for magnetic flux between the base and the cover; and

wherein the base and the cover are configured to contain a structure and the channel is configured to block the magnetic flux from encountering a portion of the structure in a direction non-parallel to the portion of the structure.

7. The apparatus of claim 6 , wherein the flux director is formed of a material that is magnetically opaque to a frequency in a range of 30 KHz to 350 KHz.

8. The apparatus of claim 7 , wherein the flux director has the channel extending through the material.

9. The apparatus of claim 8 , wherein the flux director comprises the base and the cover, wherein the base and the cover form the channel.

10. The apparatus of claim 9 , wherein the flux director further comprises: a number of inserts in a number of cavities of the base.

11. The apparatus of claim 9 , wherein a number of cavities house a number of pressure applicators.

12. A method comprising:

generating a magnetic flux using a plurality of induction coils of a tool, wherein the tool comprises a plurality of dies creating a die cavity and the plurality of induction coils, wherein sections of the plurality of induction coils are embedded in the plurality of dies; and

directing the magnetic flux using a flux director positioned within the die cavity;

wherein the flux director comprises a base, a cover, and a channel for magnetic flux between the base and the cover; and

wherein the base and the cover are configured to contain a structure and the channel is configured to block the magnetic flux from encountering a portion of the structure in a direction non-parallel to the portion of the structure.

13. The method of claim 12 further comprising:

inserting the base of the flux director into the die cavity, wherein the base is formed of a material that is magnetically opaque to a frequency in a range of 30 KHz to 350 KHz.

14. The method of claim 13 further comprising:

positioning the cover of the flux director relative to the base to form the channel, wherein the cover is formed of the material.

15. The method of claim 13 further comprising:

positioning a first component and a second component to be joined relative to the base.

16. The method of claim 15 , wherein directing the magnetic flux using the flux director comprises:

directing the magnetic flux to a number of joints between the first component and the second component.

17. The method of claim 16 , wherein directing the magnetic flux to the number of joints between the first component and the second component comprises:

directing the magnetic flux through the channel formed by the base and the cover of the flux director.

18. The method of claim 15 , wherein directing the magnetic flux using the flux director comprises:

shielding a portion of the first component that is non-parallel to the plurality of dies from the magnetic flux.

19. The method of claim 15 further comprising:

activating a pressure applicator in a cavity of the base to apply pressure to the first component and the second component.