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Rapid-Growth Technology for Soluble Crystals

#1712


Development of Rapid-Growth Technology for the Production of Single-Sector Water-Soluble Crystals (2-nd stage)

Tech Area / Field

  • MAT-SYN/Materials Synthesis and Processing/Materials

Status
3 Approved without Funding

Registration date
14.12.1999

Leading Institute
Russian Academy of Sciences / Institute of Applied Physics, Russia, N. Novgorod reg., N. Novgorod

Supporting institutes

  • VNIIEF, Russia, N. Novgorod reg., Sarov

Collaborators

  • Lawrence Livermore National Laboratory, USA, CA, Livermore\nCrismatec, France, Paris\nSAGEM SA/Devision Defense et Securite, France, Paris

Project summary

The production of monocrystal plates - radiation frequency converters and electrooptical modulators - from KDP and DKDP crystals remains one of the most expensive stages in the construction of high-power laser systems with frequency conversion. Recent investigations carried out in MSU, LLNL and IAP RAS have proved that technologies of rapid growth of large crystals can provide needed sizes and quality of crystals as well as much higher efficiency compared to that provided by traditional technologies. Therefore, the problem is specified now to upgrade the rapid-growth technologies to the level of commercial ones capable of future highly efficient developing of high-power laser system facilities with radiation frequency conversion.
The project deals with one of rapid-growth technologies - the technology of rapid growth suggested and developed in IAP RAS.
The principal advantage of this technology compared to others is the growth carried out by a single crystal sector and, thus, there are no intersectorial boundaries in optical elements, which affect the parameters of a frequency converter or the Pockels cell. The second very important advantage is the practically wasteless production of elements. This circumstance makes the developed technology one of the most promising ones. The suggested Project is the continuation of ISTC project No.223-95 in which the problem is stated to develop grounds of a high-efficiency technology for producion of monocrystal plates-samples with the cross-section up to 40x40 cm from the KDP type crystals for applications in high-power laser systems (of NIF, LMJ types et al.).
The results of project No.223-95 accomplishment can be briefly formulated as follows:
1. The type I technology is developed for growing crystal plates of the (101) orientation, the cross-section 40x40 cm and
thickness ~ 7 cm. Plates-samples of optical quality elements of the cross-section 38x42 cm are obtained.
2. The type II technology is elaborated for growing crystal plates of frequency multipliers with oee synchronism (=00)
with an arbitrary angle and of Pockels cell elements (z-orientation) with the cross-section ~ 30x30 cm of the optical quality.
3. The equipment is designed and partially manufactured for growing samples of elements of the cross-section 41x41 cm and thickness 5 cm using the type II technology.
4. The type II technology of growing plates-samples of frequency multiplication elements with oee synchronism (=450) is suggested and tested.
5. The crystal quality is investigated. The investigations have shown that according to the optical homogeneity crystals satisfy modern requirements. Laser stability at the I and II harmonics of a neodymium laser was examined using the example of rapidly grown crystals of a small cross-section. It is demonstrated that the combination of optimal technological growth conditions with the postgrowth thermal treatment of crystals enables one to obtain crystals with sufficient laser stability.
It is seen from the mentioned results that the developed technologies can reasonably serve as a basis for arrangement of high-efficiency production of KDP crystal samples for the most promising laser systems. However, the performed investigations and the laser engineering progress have specified a number of new problems to be solved for successful development of the technology and arrangement of a competitive production of crystals and elements which will be able to satisfy the demands of current laser projects. The basic of these problems are:
1. To design, manufacture the equipment and develop the type I technology for growing crystals with the cross-section 41x41 cm and the height ~ 20 cm with assigned turn of the x axis in the element plane for fabricating plates-samples of frequency multipliers with the oee type synchronism normally oriented to the laser beam.
2. To develop the type II technology for growing plates-samples of the cross-section 41x41 cm ( = 00 orientation).
3. To develop a technology for wasteless production of plates-samples with = 450.
4. To develop methods for deep cleaning of the equipment and growth solution with their employment directly in the crystal growth cycle.

5. To develop technological growth and postgrowth technique providing sufficient laser stability for crystals of a large cross-section.
6. To investigate obtained elements in large-scale experiments.
The mentioned basic problems comprise the continuation of physico-chemical investigations on morphological stability of growing crystals, solution stability to mass crystallization, etc. A separate problem is upgrading the technology of optical treatment of large crystals based on diamond microturning methods to the level ensuring thorough investigation of crystal quality and application of produced optical elements in laser systems. All the investigations will be carried out in maximum possible co-operation with the collaborators, taking into account their R&D achievements. The final task of the 2nd stage is the arrangement of inpidual fabrication of large crystal samples and optical elements from KDP, DKDP crystals for research purposes and working out recommendations for the small-batch production arrangement.
The solution of the problems stated above is the goal of the 2nd stage of the Project. The 2nd stage activities will fully involve the experience, methods and material resources gained recently both due to ISTC facilities and own resources of the institures-executers.

Expected results:

1. Equipment will be constructed and the type I technology will be elaborated for growing crystal blocks of the (101) orientation and the cross-section 41x41 cm for fabricating optical generators of frequency harmonics with the oee type synchronism.
2. The type II technology will be developed for wasteless growth of plates of the cross-section 41x41 cm with =0 and the necessary orientation angle .
3. A low-waste technology for growing plates with the orientation = 450 and the necessary (frequency multipliers with ooe synchronism) will be elaborated.
4. A closed cycle technique included in the crysal growth cycle will be developed for cleaning the growth equipment and solutions.
5. A technology for growing plates of 41x41 cm and Z-orientation will be developed.
6. Inpidual fabrication of the assigned products will be arranged.
7. A technology for diamond microturning on the turning machine SAF-600 complex available in IAP RAS will be elaborated for meeting the requirements of laser systems; the complex provides processing parameters comparable with parameters obtained by companies which are most advanced in this field and essentially lower cost of processing.
8. Recommendations for the small-batch production arrangement will be formulated.
The technical approach and methods employed at the I stage will be mainly conserved at the II stage. It is natural that the experience and new scientific results obtained at the I stage as well as the results obtained by the reserachers-collaborators and other scientists dealing with this field will also be taken into account.
The main works on the technology development will, as previously, be carried out in IAP RAS and RFNC-VNIIEF. The foreign collaborators are: LLNL (USA) and Crismatec (France) will participate in discussion of plans and results of works, in theoretical and experimental works and crystal test. The participation of other collaborators in the Project is also possible.


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