TECH MORE SO UNDERSTOOD:
edtn.com
iamonds are used elsewhere, not Rhombic, but a VERIFICATION of DIAMOND TECH: IMHO:
iamond Hikes Power Levels Of Resistors And Terminations
he availability of high-quality diamond substrates has led to the development of high-power resistors and terminations.
Thomas Dowling and Elliot Lewis
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DIAMOND heat sinks have long been known as tremendous heat conduits. Unfortunately, the high cost of the material has limited its application in high-frequency designs until now. With recent advances in both diamond-substrate material processing and thin-film technology, the engineers at RF Power Components, Inc. (Bohemia, NY) have been successful in developing lines of cost-effective, high-power drop-in resistors and terminations with as much as 200-W power-handling capability at 4 GHz.
hese resistors and terminations are built with CVD diamond heat spreaders for high power-handling capability at high frequencies.
he new resistors and terminations (see figure) are housed in drop-in and flange-mount packages. A total of four resistors and four terminations comprise the initial product lines (Table 1). Model RFP-100-100DR, for example, is a high-power resistor with only 0.4-pF capacitance that can be used past 8 GHz. It is rated for 100-W power-handling capability. A 50-W 100-W termination, model RFP-100-50-DT, exhibits VSWRs of 1.11:1 from DC to 1.5 GHz, 1.20:1 to 4.0 GHz, and 1.30:1 to 8.0 GHz. The drop-in package measures 0.16 × 0.08 × 0.05 in. (4.06 × 2.03 × 1.27 mm).
HIGH-POWER RESISTOR
odel RFP-200-100DRVV is a flange-mount 200-W resistor with only 0.54-pF capacitance and can be used in applications past 4 GHz. As a termination with the same power-handling capability, model RFP-200-50DTVV exhibits VSWRs of 1.11:1 from DC to 2 GHz, 1.20:1 to 3 GHz, and 1.30:1 to 4 GHz. The flange-mount package measures 0.50 × 0.16 × 0.13 in. 12.7 × 4.06 × 3.30 mm).
The availability of high-power components based on diamond substrates is critical for several reasons. As more communications systems, such as personal-communications-services (PCS) networks, rely on high-power but unobtrusive cell sites and base stations, engineers are pressured to design smaller, more robust power combiners and terminations. Diamond provides better thermal resistance than beryllium oxide (BeO) substrates. Diamond substrates are nontoxic, which make them attractive in light of increasing Environmental Protection Agency (EPA) restrictions and in environmentally-sensitive areas, such as Europe, which restrict the use of BeO substrates.
Diamond is superior in its thermal characteristics to such materials as BeO and AlN, and has a lower dielectric constant than most commonly-used heat spreaders (Table 2). The use of diamond heat spreaders permits conventionally-accepted performance limits for power density, component size, and frequency to be dramatically extended, such as in the new lines of high-power resistors and terminations.
It is now practical to develop diamond-based high-power passive components in part due to advances in chemical-vapor-deposition (CVD) diamond processing, which allows the production of high-quality, large-area diamond wafers. The change can also be credited to improvements in thin-film processing, allowing strong bonds to be made between metallized films and diamond substrates in spite of the diamond's lack of an oxided ceramic phase (which normally aids adhesion).
On the material-processing side, Crystalline Materials Corp. (San Ramon, CA) has been able to develop uniform CVD diamond substrates called the CrystalCool heat spreaders. The firm offers various thicknesses in sizes that are precisely laser cut to a customer's specifications. The company has successfully reduced numerous cost drivers from optimizing deposition rates, including minimizing the cost of energy (the firm's diamond fabrication plant is located in Calgary, Alberta, Canada, in a region known for its low cost of electricity).
MAKING DIAMOND
Crystalline Materials Corp. has been able to deposit larger areas of diamond, resulting in dramatic increases in yield and capacity.
The company's efforts have resulted in a cost reduction of diamond substrates by a factor of 10 during the last three years. The CVD process yields free-standing diamond material from 0.01 to 0.04 in. (0.25 to 1.02 mm) thick in industry-standard substrate sizes. Polycrystalline CVD diamond is produced by condensing carbon atoms derived from a carbon and hydrogen gas mixture onto a substrate. The carbon source is usually methane, carbon monoxide, or acetylene. This gas mixture is activated by heating between 2000 to 5000 K by means of microwave energy, combustion, or DC plasma heating. Such high temperatures dissociate the hydrogen molecules to produce atomic hydrogen; atomic hydrogen stabilizes the diamond material during growth and suppresses the formation of graphite. The activated gas impinges on a substrate maintained in a vacuum between +700 and +1100°C.
The substrate must be prepared so that the surface promotes the nucleation of the tight tetrahedral bonds characteristic of diamond. Deposition rates can range from 1 to 100 mm/hour depending on the carbon transport mechanism. Crystalline Materials Corp. employs a proprietary DC arc-jet technique which offers the highest deposition rate available. After the diamond has grown to a specified thickness, the free-standing diamond substrate is separated easily from its growth substrate, polished, and then cut to size.
COMBINING SKILLS
orking with this materials supplier, the engineers at RF Power Components have combined their processing capabilities to the diamond substrates in order to produce resistors and terminations that are compatible with RF/microwave industry standards. In many cases, these resistors and terminations will drop into existing conventional circuits. Construction is similar to existing ceramic resistors and terminations based on thin-film technology.
As an example, a diamond-based resistor with a chip size of 0.080 × 0.155 × 0.025 in. (2.03 × 3.94 × 0.64 mm) and a resistor film size of 0.03 × 0.10 in. (0.76 × 2.54 mm) provided power dissipation of 100 W. The thermal resistance for this unit is 0.5°C/W, with operation at 100 W resulting in a flange temperature of +87°C and a resistor film temperature of +137°C (for a temperature delta of 50°C).
Designers who require compact, high-power/high-frequency resistors or terminations with low parasitic capacitances and low VSWR performance will find the devices quite useful. The resistors permit the construction of power combiners and dividers with high power-handling capability, low insertion loss, and high isolation. While the cost of the patent-pending diamond-based resistors and terminations is somewhat higher than that of BeO devices, overall manufacturing costs may be comparable. External resistor matching is virtually eliminated with the diamond-based devices, resulting in less circuit losses, less overall associated passive components, and less occupied printed-circuit-board space. P&A: stock. RF Power Components, Inc., 125 Wilbur Pl., Bohemia, NY 11716-2482; (516) 563-5050, FAX: (516) 563-4747.
Now I give CREDIT to Kathy Knight-McConnell for her fine write up: ( Below )
see here Home Page
investortoinvestor.com
....It is a small
metallic football shaped sphere and it's primary purpose is not to make
energy but to generate neutrons. Billions of them a second. Neutrons are
subatomic particles with no electric charge that have an extraordinary range
of uses such as: 1) To analyze materials, neutrons can be used to identify
most common elements in a matter of seconds versus chemical analysis which
can take hours 2) Neutrons help scientists to work out the structure of new
molecules and crystals 3) Neutron particle beams are being used for cancer
treatment and I have been told that the IEC unit has now surpassed 10^9 power
neutrons per second, which is powerful enough for that purpose 4) Mining
companies can use the neutron generator to spot impurities in ores while
still in the process of being mined 5) Specialized metal smelters will use
them to monitor the composition and quality of metal alloys in real time.
Chucka-FUSION TECH paragraph is just above via Kathy - a re cap for a Knitecap!
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