Sunder S Rajan, 796433 E Lookout Ln, Anaheim, CA 92807

6584675, Jul 1, 2003

Jun 9, 2000

09/591697

Sunder S. Rajan - Anaheim CA, 92807

H01Q 1300

29600, 295921, 315 33, 315 36, 315 393, 333162, 430323, 427271, 216 67

A method for constructing thermally and dimensionally stable traveling wave tube circuits having high dimensional stability, narrow tolerances, and very small size by providing a small hollow preform constructed of a desired material which is coated with a layer of photoresist material then exposed to a UV laser to form a desired pattern mask in the photoresist layer. The pattern masked preform is then etched to create a preform having a desired shape. After shaping, the photoresist coating is stripped from said shaped preform to form a traveling wave tube circuit. Optionally the travel wave tube circuit may be polished. Additionally, the present invention contemplates an apparatus for forming small three dimensional circuit structures from preforms comprising a chuck for supporting the preform on its axis, a motor for rotating the preform, a UV laser for directing a beam onto the preform, a means for shifting the laser along said preform, and a controller for controlling the motors rate of rotation, the rate of movement along the length of the preform caused by shifting means, and whether the laser is on or off to achieve a predetermined pattern mask on the preform. Additionally, the present invention contemplates novel three dimensional structures including a very small helical traveling wave tube circuit, a ringed bar circuit structure, a finned ladder circuit structure, and a slotted finned ladder circuit structure as well as traveling wave tubes incorporating these structures.

2007009, Apr 26, 2007

Oct 20, 2005

11/255432

Bradley Ross - Los Olivos CA, US
Michael Brest - Goleta CA, US
Sunder Rajan - Anaheim CA, US

F25B 9/00
F16J 15/00

277500000, 062006000, 277585000

Provided is a low friction, self-lubricating sleeve for use with a reciprocating piston in the compressor and/or the expander subsystem of a cryogenic cooler or other compressor type system. The sleeve is bonded to an outer surface of the piston, thereby positioning the sleeve between the piston and an inner wall of a piston cylinder. The sleeve is manufactured using a polyetheretherketone base material, as well as varying percentages of carbon and/or polytetrafluoroethylene fillers. The sleeve may include a dry lubricant such as graphite or molybdenum disulfide, and may extend for all or part of the length of the piston. The sleeve demonstrates negligible wear over thousands of hours of use in the cryogenic cooler, thereby minimizing system gas blow-back and maximizing system efficiency/performance.

2010013, Jun 3, 2010

Feb 1, 2010

12/698051

Bradley A. Ross - Los Olivos CA, US
Michael L. Brest - Goleta CA, US
Sunder S. Rajan - Anaheim CA, US

RAYTHEON COMPANY - Waltham MA

F25B 9/14
F16J 9/28

62 6, 92248

Provided is a low friction, self-lubricating sleeve for use with a reciprocating piston in the compressor and/or the expander subsystem of a cryogenic cooler or other compressor type system. The sleeve is bonded to an outer surface of the piston, thereby positioning the sleeve between the piston and an inner wall of a piston cylinder. The sleeve is manufactured using a polyetheretherketone base material, as well as varying percentages of carbon and/or polytetrafluoroethylene fillers. The sleeve may include a dry lubricant such as graphite or molybdenum disulfide, and may extend for all or part of the length of the piston. The sleeve demonstrates negligible wear over thousands of hours of use in the cryogenic cooler, thereby minimizing system gas blow-back and maximizing system efficiency/performance.

2013015, Jun 20, 2013

Dec 16, 2011

13/328362

Sunder S. Rajan - Anaheim CA, US

C22F 1/00
C21D 9/52

148559, 148402

A shape memory alloy including a Ni—Ti based alloy is superelastic at temperatures of about −40 C. to about 60 C. after being exposed to temperatures of about −55 C. to about 85 C. A method of forming a memory shape alloy may include preparing a rod comprising a Ni—Ti alloy, drawing a wire from the rod, and treating the wire at a temperature of about 500 C. to about 550 C. for about less than 1 minute.

5130206, Jul 14, 1992

Jul 29, 1991

7/736844

Sunder S. Rajan - Anaheim Hills CA
Ivo Tammaru - Rancho Palos Verdes CA
Steve L. Bosma - Torrance CA
John W. Eldridge - Lakewood CA

Hughes Aircraft Company - Los Angeles CA

G22F 300

428552

Extra loss is introduced in coupled cavity and klystron RF circuits by applying a surface coating to selected parts of circuit elements used in the circuits. The coating is applied in the form of a slurry, which is then sintered. The slurry comprises a mixture of an iron-base powder (such as a stainless steel) and a dielectric glass ceramic, suspended in a binder dissolved in a solvent. Circuits with the loss coating are easier to match than by other prior art techniques. The loss coating of the invention reduces the fabrication cost of coupled-cavity traveling wave tubes, while improving the performance by minimizing the gain ripple. Higher average power operation is possible, due to elimination of loss buttons previously employed in the prior art.

5051656, Sep 24, 1991

Sep 5, 1989

7/402723

Sunder S. Rajan - Anaheim CA
Roger S. Hollister - Torrance CA
Thomas P. Carlisle - Rolling Hills Estates CA

Hughes Aircraft Company - Los Angeles CA

H01J 2324

315 35

In a travelling-wave tube (20), a cylindrically-shaped slow-wave circuit cavity-defining member (34) is supported by and is thermomechanically bonded to a tubularly-configured vacuum wall member (32). The bonded joint comprises a pair of arcuate grooves (52) extending lengthwise of the slow-wave circuit and positioned diametrically opposite one another about the axis of the tube. A helical or wavy spring (54, 58) lies in each groove and is resiliently biased in intimate mechanical and thermal contact between the groove and the vacuum wall. The helical spring, in particular, can be used as a conduit for exhaust of gases from the travelling-wave tube during its fabrication.

2018009, Apr 5, 2018

Oct 3, 2016

15/283673

- Waltham MA, US
Sunder S. Rajan - Anaheim CA, US
Scott T. Turner - Redondo Beach CA, US
Isaac C. Chen - Alhambra CA, US

C03C 8/14
B28B 3/00

A molding composite includes mica flakes and a eutectic glaze. The composite allows making of lead-free parts for use in a variety of situations, such as electrical insulators for supporting electrically-conductive parts, such as electrodes, for electrical devices. The molded composite material can be used mold around such electrically-conductive parts, supporting them and/or providing hermetic seals around the parts. Other possible uses include substrates for electronic circuits, and housings for parts, such as electro-optical parts. The molding composite is heated under elevated pressure to liquefy the eutectic glaze, causing it to coat the mica flakes. After the composite is put into a desired shape it is solidify, for example by compressing the molding composite at a constant temperature until the eutectic glaze solidifies, followed by cooling of the molding composite.