Abstract:
A continuous use chemical oxygen iodine laser requires a continuous supply of basic hydrogen peroxide and chlorine to produce singlet delta oxygen for the laser. Regeneration of the spent basic hydrogen peroxide and chlorine with the input of oxygen and electricity can be generated on site or be obtained from a power grid. The regeneration of the spent basic hydrogen peroxide and chlorine makes continuous use of a chemical oxygen iodine laser possible without the constant resupply of basic hydrogen peroxide from an outside source.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates to in-situ electrochemical regeneration of alkaline hydrogen peroxide and chlorine for a continuously operating chemical oxygen-iodine laser, which can be used for high energy material processing applications.  
         DESCRIPTION OF THE RELATED ART  
         [0002]    Prior art has established that COIL (Chemical Oxygen-Iodine Laser) is capable of delivering a high power laser beam with excellent beam quality and at a wavelength compatible with optical fibers. These characteristics make COIL a candidate for a variety of industrial applications in material processing, where high power, high-brightness, and beams delivered by optical fiber can provide economic and/or technological advantages over existing industrial lasers such as carbon dioxide (CO 2 ) and Nd:YAG lasers. High-brightness lasers with 10-25 kW power can improve existing laser oriented industrial processes and can facilitate development of certain emerging applications such as aluminum cutting and welding, thick section cutting for dismantlement of nuclear installations, laser driven x-ray lithography, and pulsed laser vapor deposition.  
           [0003]    In COIL the laser power is produced by extraction of energy from a flow of excited gas produced by reaction of chemical fuels. Sustaining continuous operation, such as required for many industrial and government applications in material processing, requires a continuous flow of fuel must be provided. In prior art, fresh fuel obtained from commercial suppliers was used to operate COIL. However, the costs associated with providing fresh fuel and disposing of reaction products make use of COIL for industrial applications uneconomical and have been a leading impediment to developing commercially useful COIL devices.  
           [0004]    Laser power in COIL is derived from chemical energy released by reacting Chlorine gas and Basic (alkaline) Hydrogen Peroxide (BHP), an aqueous solution of hydrogen peroxide and potassium (or sodium) hydroxide, to generate singlet oxygen which produces and excites atomic iodine to a laser transition (disclosed by McDermott in U.S. Pat. No. 4,267,526). In prior art, BHP was prepared by mixing highly concentrated solutions of hydrogen peroxide and potassium hydroxide obtained from commercial suppliers. Chlorine was also commercially obtained in a form of liquefied gas. The by-product of the BHP reaction with chlorine, namely aqueous solution of potassium chloride (which normally includes some unreacted BHP) was disposed of as a hazardous waste.  
           [0005]    Using raw fuels in this manner to operate COIL on a continuous basis has several disadvantages. First, raw fuels are relatively expensive and their continuous supply requires significant logistics. Highly corrosive nature of the fuels requires significant safety precautions during their transport, handling and storage. Similar considerations apply to disposal of reaction by-products. In addition, due to thermal decomposition of peroxyl anions BHP has a short shelf life which precludes maintaining a large inventory for use with COIL.  
           [0006]    Typical COIL systems operate with a predetermined quantity of BHP liquor that is continuously recirculated within the system and reacted with chlorine gas. During each contact with chlorine some of the peroxyl and hydroxyl anions in the BHP are depleted in a reaction which generated singlet oxygen as the primary product, singlet oxygen is separated as gas, and salt and water as secondary products that become a part of the recirculating BHP liquor. The reaction thus reduces concentration of peroxyl and hydroxyl anions in the liquor, increases liquor volume by addition of water, and increases its salt content.  
           [0007]    COIL systems have been operated wherein the entire quantity of BHP required to sustain limited time operation was prepared in advance and the laser operated until the BHP concentration was reduced to the point at which the laser would no longer function efficiently, at which time the residual BHP liquor was drained and replaced with fresh liquor.  
           [0008]    Other COIL systems have been proposed where the quantity of BHP liquor continuously recirculates within the system and reacting with chorine. The system is continuously provided with chlorine as well as fresh highly concentrated hydrogen peroxide and potassium hydroxide while removing water and potassium chloride salt. This method maintains a proper concentration of peroxyl and hydroxyl anions in the BHP liquor and allows continuous operation of a COIL laser.  
           [0009]    In either case fresh chemical fuel required to operate the laser, namely hydrogen peroxide, potassium hydroxide, and chlorine fuel must be provided from external sources and the reaction byproducts disposed of in an environmentally safe manner. Thus a continuous operation of COIL in this fashion necessitates significant monetary expense and logistical support.  
         SUMMARY OF THE INVENTION  
         [0010]    The invention is for electrochemical regeneration of Basic Hydrogen Peroxide (BHP) and chlorine for use in a Chemical Oxygen-Iodine Lasers (COIL). Depleted (reduced peroxyl strength) BHP from the singlet delta oxygen generator is recycled through an electrochemical cell which simultaneously regenerates BHP to its full strength and produces chlorine, both for use in the singlet delta oxygen generator.  
           [0011]    The electrochemical regenerator cell has two compartments separated by a cation-exchange membrane. In the anode compartment chlorine is produced by electrolysis of potassium chloride and in the cathode compartment peroxyl and hydroxyl anions are produced by electrosynthesis of water and oxygen. In this fashion the electrochemical cell essentially reverses the singlet delta oxygen-producing reaction between BHP and chlorine by reconstituting the original reactants. Electrochemical regeneration of BHP and chlorine allows the COIL system to operate only on electricity and atmospheric oxygen without external source of hydrogen peroxide, potassium hydroxide, and chlorine.  
           [0012]    The use of such a regenerative system would reduce or eliminate the need to supply external sources of reactants for use in a COIL. This would reduce the time and energy used to supply such elements and the space necessary to inventory such elements for use in a COIL. Additionally, this would also reduce the cost of a COIL since only an initial external supply of reactant elements is necessary which are then regenerated within the system itself. Finally, this would also significantly reduce the amount of hazardous material produced by a COIL laser.  
           [0013]    Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0015]    [0015]FIG. 1 shows a schematic of a chemical oxygen iodine laser with the preferred configuration of the chlorine and basic hydrogen peroxide regeneration equipment;  
         [0016]    [0016]FIG. 2 shows details of the electrolytic regeneration cell with packed bed cathode;  
         [0017]    [0017]FIG. 3 shows details of the electrolytic regeneration cell, trickle flow cathode; and  
         [0018]    [0018]FIG. 4 shows a flow diagram for the regeneration of basic hydrogen peroxide and chlorine and a list of chemical reactions. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]    The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
         [0020]    In reference to FIG. 1, a Chemical Oxygen-Iodine Laser (COIL)  10  uses a continuous reaction of Basic Hydrogen Peroxide (BHP)  12  and a mixture of chlorine and nitrogen gas  14 , which is supplied to a singlet oxygen generator  20  to produce excited oxygen gas in a metastable state known as the singlet delta oxygen (O 2 ( 1 Δ)). The O 2 ( 1 Δ) leaves the singlet oxygen generator  20  in line  22  and is mixed in a nozzle  30  with a continuous supply of iodine vapor entrained in nitrogen from line  32 . The iodine vapor supplied to the nozzle  30  is stored in a solid or liquid form in a reservoir  36  and is vaporized in iodine vapor generator  34 . The iodine vapor fed in line  33  is mixed with nitrogen from line  89  in mixer  97  and the mixture is carried in line  32  to nozzle  30 . This process facilitates an energy transfer from the O 2 ( 1 Δ) to the iodine in nozzle  30 , by dissociating iodine molecules into atoms and bringing the iodine atoms to an electronically excited state known as  2 P ½ . Using a suitable laser cavity  31  with an optical resonator comprising mirrors  50  and  51  a beam of coherent laser light  45  can be extracted from the inverted population of the exited iodine atoms as shown in a process disclosed by McDermott in U.S. Pat. No. 4,267,526. During this process the excited iodine atoms decay from a high energy state  2 P {fraction (1/2 )}  to a lower energy state  2 P {fraction (3/2 )}  while releasing photons at a 1.315 micrometer wavelength.  
         [0021]    In order to improve laser performance, nitrogen gas, which does not take part in any reactions here and is used only as a diluent, is added to the chlorine gas and to the iodine vapor. Line  91  which is the nitrogen outlet of the air separator  85  branches out to line  88  and  89  which feed nitrogen gas to mixers  96  and  97 . The mixer  96  receives and mixes nitrogen  88  and chlorine  13  and feeds the mixture through line  14  to the oxygen generator  20 . The mixer  97  receives and mixes nitrogen  89  and iodine vapor  33  and feeds the mixture of nitrogen and iodine vapor through line  32  to the COIL nozzle  30 . Additional nitrogen purge gas may be added to the flow in laser cavity  31  to protect optical components.  
         [0022]    The flow of gas containing oxygen, iodine, diluent and unreacted chlorine in line  46  from laser cavity  31  to iodine trap  52 , wherein most of the iodine vapor is separated from the flow by condensation and collected for eventual reuse in the system. Unreacted chlorine and a residual trace amount of iodine are removed from the flow in a scrubber  56  by reacting the feed from line  47  with an aqueous solution of suitable reactive chemicals (e.g. mixture of potassium hydroxide, potassium iodide, and sodium thiosulfate). This process assures that system effluents do not constitute environmental and safety hazards. Gas flow  48 , free of iodine and chlorine, is fed into a vacuum pump  54  and exhausted through line  58  into the atmosphere.  
         [0023]    Continuous regeneration of chemicals expended in the oxygen generator  20  is accomplished by recirculation of the BHP electrolyte between the oxygen generator  20  and the regeneration cell  100 . The BHP is an aqueous electrolyte containing O 2 H − , OH − , and Cl − anions and K + cations and possibly solid KCl. The strength of H 2   0   2  in fresh BHP liquor is approximately 12% by weight and the molar ratio of KOH and H 2 O 2  is about 1.0. It should be noted that concentrations of KOH and H 2 O 2  are strongly influenced by the performance of the peroxide producing cathode. The actual concentration of BHP electrolyte varies along the recirculation loop. In particular, the O 2 H − and OH − anions are depleted and Cl − anions are added in the oxygen generator  20 . Conversely, O 2 H − and OH − anions are added and Cl − anions are depleted in the regeneration cell  100 . In this process, the regeneration cell  100  reconstitutes BHP liquor to its original composition and generates chlorine gas by reversing the reaction taking place in the oxygen generator  20 .  
         [0024]    The singlet oxygen generator  20  takes in Cl 2  mixed with nonreactive nitrogen  14  and fresh (higher O 2 H − concentration) BHP liquor  12  and reacts these for the purpose of generating singlet oxygen according to the reaction:  
         Cl (g) +2O 2 H −   (aq) +2K +   (aq)  →O 2 ( 1Δ ) (aq) +2KCl (s)    
         [0025]    During this process most of the chlorine gas (about 99%) and only few percent of the O 2 H − anions delivered to the oxygen generator  20  are actually reacted. Mixture of singlet delta oxygen, nitrogen diluent, and unreacted chlorine is carried in line  22  out of the oxygen generator  20 . Unreacted O 2 H − anions together with reaction products H 2 O 2  and KCl are contained in the spent (reduced O 2 H − concentration) BHP is directed through line  60  into the receiving tank  62 . The receiving tank  62  acts as a surge tank for a pump  74  which receives depleted BHP in line  72  and pumps the liquor BHP in line  76  to the cathode compartment  101  in the regeneration cell  100 .  
         [0026]    The regeneration cell  100  has two compartments  101  and  102  separated by a cation exchange membrane  150 . The cathode compartment  101  employs a cathode for electrosynthesis of O 2 H − and OH − anions from oxygen and BHP electrolyte. Gaseous O 2  from oxygen output of an air separator  85  fed in line  86  is combined with a flow of excess oxygen  70  from oxygen separator  69  in mixer  68  and provided in oxygen feed line  73  to cathode compartment  101 . The air separator  85  is a commercial unit which receives atmospheric air  84  and separates it into relatively pure oxygen in line  86  and relatively pure nitrogen in line  91  using well known processes such as pressure-swing adsorption or membrane diffusion.  
         [0027]    The cathode receives depleted BHP liquor provided into the cathode compartment  101  through line  76  and oxygen provided through line  73 . The cathode has a porous, high surface area and it is of the type as used in industry for electrosynthesis of alkaline hydrogen peroxide from the aqueous solution of sodium hydroxide and oxygen. The porous nature of the cathode provides a large contact surface between the electrolyte and oxygen gas which allows oxygen gas, thereby allowing efficient reaction. With an application of electric current the cathode synthesizes oxygen and water contained in the electrolyte into alkaline (basic) peroxide following the reaction.  
         O 2 +2H 2 O+2e − →O 2 H −   (aq) +OH −   (aq)    
         [0028]    (see equation 3 in FIG. 4)  
         [0029]    The OH − anion reacts with H 2 O 2  previously added to the electrolyte in the singlet oxygen generator  20  (see equation 5 in FIG. 4) to produce another O 2 H − anion and water molecule according to  
         OH − (aq)+H 2 O 2 →O 2 H − +H 2 O  
         [0030]    (see equation 4 in FIG. 4)  
         [0031]    The regenerated BHP liquor (i.e. with increased O 2 H − ) concentration is transported out of the cathode compartment  101  in line  77  to a separator  69  where entrained excess oxygen is separated from the liquid. Separated excess oxygen is then returned in line  70  to mixer  68  where it is added to the flow of fresh oxygen  86  and fed in line  73  to the cathode compartment  101 . A stream of BHP liquor  66  from the separator  69  is directed to concentrator  99  where excess water is removed from the BHP liquor and discharged through line  61 . Concentrated BHP liquor is transported in line  65  to heat exchanger  78  where the BHP liquor is cooled and sent in line  80  to salt separator  90 . Cooling the BHP liquor removed the heat added to the liquor in the oxygen generator  20  and the electrolytic cell  100  forces excess KCl out of the solution. The salt separator  90  removes KCl solids from the BHP liquor. BHP liquor free of KCl particles is then transported in line  12  back into the singlet oxygen generator  20 , thereby completing a full pass through the recirculation loop.  
         [0032]    The KCl solids removed from the BHP liquor in salt separator  90  are transported in line  95  to the mixer  65  where the KCl is mixed with deleted anolyte liquor fed in line  15  from chlorine separator  67 . The anolyte liquor is an acidic aqueous solution of KCl which is recirculated by pump  18  in a closed loop fashion. KCl dissolves in the anolyte liquor and is ionized as  
         2KCl (5) →2K +   (aq) +2Cl −   (aq)    
         [0033]    (See equation 1 of Figure.  4 )  
         [0034]    Anolyte liquor replenished with KCl is transported in line  16  to pump  18  which pumps anolyte liquor into anode compartment  102  of the regeneration cell  100 . In the anode compartment  102  a conventional anode electrode as used in the chlor-alkali industry generates chlorine gas according to  
         2Cl − (aq)-2e − →Cl 2 (g)  
         [0035]    (See equation 2 of FIG. 4)  
         [0036]    The chlorine gas generated on the anode is entrained in the flow of depleted anolyte and transported from the anode compartment  102  in line  11  to a gas-liquid separator  67  where chlorine gas is separated from the anolyte liquor. Separated chlorine gas is them transported in line  13  to mixer  96  to combine it with nitrogen from line  88 . The mixed nitrogen and chlorine is directed through line  14  to singlet oxygen generator  20 , thereby completing a full pass through the recirculation loop. Depleted anolyte liquor largely free of entrained chlorine gas is returned in line  15  from separator  67  to mixer  65  where KCl slurry from line  95  is mixed into the flow. The mixture is provided in line  16  to pump  18  which returns the anolyte through line  19  back into the chlorine compartment  102 . KCl solids mixed into the flow by mixer  65  become dissolved as the anolyte is being returned to the chlorine compartment  102  of cell  100 . Potassium cations K + (aq) produced in the anolyte by dissolving KCl solids are returned back into the BHP electrolyte by diffusing from the anolyte into the catholyte through the cation exchange membrane  150 .  
         [0037]    The cation exchange membrane  150  can be of the perfluorinated type such as the Nafion® family (Nafion is a registered trademark of DuPont). The membrane  150  thus allows K + cations to be transported from the anode compartment  102  to the peroxide cathode  101  thereby returning K + cations into the BHP electrolyte. At the same time the membrane  150  blocks the transport of OH − and O 2 H − anions from the cathode compartment  101  into the anode compartment  102 . In order to prevent thermal decomposition of BHP both the cathode compartment  101  and anode compartment  102  are operated at a temperature near zero degrees Centigrade.  
         [0038]    The anode is preferably made of graphite to avoid possible contamination of BHP by heavy metal ions transported across the membrane  150 . Alternate material for the anode is titanium and coated with a suitable chlorine evolution catalyst. This type of corrosion resistant anode is known in the industry as a Dimensionally Stable Anode or DSA® (DSA is a registered trademark of Diamond Shamrock Technologies S.A.) and it is commonly used in commercial chlor-alkali cells. When the DSA anode is used, precautions must be taken to avoid accumulation of heavy metal ions within the BHP liquor.  
         [0039]    [0039]FIG. 2 shows an alkaline peroxide cell  100  with a preferred configuration of cathode compartment  101 . The cathode  141  is a porous, packed bed, self-draining mass, fed by catholyte  130  seepage through a liquid permeable separator-type diaphragm  142  and drained through the packed bed. The packed bed is made of graphite particle coated with a mixture of carbon black and polytetrafluorethylene. This type of cathode was developed by Dow Chemical Company for electrosynthesis of alkaline hydrogen peroxide from oxygen and water in aqueous solution of sodium hydroxide electrolyte (see U.S. Pat. No. 4,511,441 and U.S. Pat. No. 4,921,587)  
         [0040]    Depleted BHP liquor from line  76  is introduced between the cation exchange  150  and the liquid permeable diaphragm  142 , and flows through the diaphragm  142  into the porous packed bed cathode  141 . The purpose of the liquid permeable diaphragm  142  is to assure uniform flow distribution of the BHP electrolyte  130  entering the porous packed bed cathode  141 . Oxygen feedstock  73  is provided at the top of the porous, packed bed cathode  141  where is diffuses throughout the packed bed and dissolves in the BHP electrolyte  130  within the cathode. On the passage of electric current introduced to the cathode  141  by means of the current distributor  140 , oxygen and water in the electrolyte react in a previously described manner. (See equation 3 of FIG. 4). Regenerated BHP electrolyte is drained at the bottom of the porous, packed bed cathode  141  into line  77 . Suitability of the porous, packed bed, self-draining cathode for production of a concentrated basic hydrogen peroxide in electrolyte containing potassium hydroxide has been experimentally established. The cell  100  also contains anode  110  and anolyte liquor whose functions have been already described.  
         [0041]    [0041]FIG. 3 shows a second embodiment of an alkaline peroxide cell  200  with the alternate configuration of a cathode compartment  101 . The cell  200  uses a trickle flow type packed bed cathode  143  which has been previously used for electrosynthesis of alkaline hydrogen peroxide (see U.S. Pat. No. 4,118,305). The packed bed cathode  143  is made of graphite particles and is backed by a cathode plate  145 . Depleted BHP liquor flowing in line  76  is first mixed in a mixer  71  with oxygen gas fed from the air separator  85  provided by line  86  and excess oxygen returned in line  70 . The stream of BHP liquor with diffused oxygen bubbles in line  82  is directed into the packed bed cathode  143  where, owing to the high surface area of the bed, oxygen is dissolved in the BHP electrolyte and, upon passage of electrical current, reacted with the electrolyte. The mixture of regenerated BHP and unreacted oxygen gas if fed in line  77  from the cathode compartment  101  to oxygen separator  69  where oxygen gas is removed from the electrolyte and recycled into the mixer  71 . Regenerated BHP free of oxygen bubbles is fed in line  66  to the concentrator  99 .  
         [0042]    [0042]FIG. 4 shows the balance of the recirculating species and the reactions occurring in the loop. Equation 5 shows the reaction in the singlet delta oxygen generator  20  where chlorine gas is used to react with peroxyl anions in BHP electrolyte to produce singlet delta oxygen, hydrogen peroxide and potassium chloride.  
         [0043]    The potassium chloride from equation 5 is used to replenish the anolyte liquor in the mixer  65  as shown by equation 1 in FIG. 4. Equation 2 shows how the chlorine gas is produced on anode  110  by electrolysis of the anolyte  120 . Potassium cations are transported out of the anolyte  120  and through the cation exchange membrane  150  into the BHP electrolyte  130  in the cathode compartment  101  from there they are carried by the BHP flow into the oxygen generator  20  and there they participate in formulation of KCl (equation 5).  
         [0044]    The hydrogen peroxide produced by the reaction in the oxygen generator  20  (equation 5) is used to form peroxyl anion from the hydroxyl anion (equation 4) produced by the cathodic process (equation 3).  
         [0045]    Thus a closed loop for regeneration of BHP and chlorine is presented where the chemical energy released to COIL  10  is replaced by the addition of electricity from an outside source and the oxygen vented to atmosphere  56  is replaced by an atmospheric oxygen  86  added to the cathode. Nitrogen diluent vented from the system through line  58  is replenished by atmospheric nitrogen  91  provided by an air separation unit  85  which is also a source of oxygen  86  for the cathode compartment  101 .  
         [0046]    When continuously operating the COIL laser  10  with the regeneration loop, all processes must be balanced to assure proper production and flow of all species. In particular, cation exchange membranes are known to “pump” water from anolyte  120  to catholyte  130 . In order to avoid the chlorine compartment  102  running dry and the BHP electrolyte becoming too dilute, water has to be added to the anolyte  120  to compensate for the amount water transported by the cation exchange membrane  150 . This is in-part accomplished by allowing the KCl sludge feed line  15  to include a small amount of BHP recirculated loop liquor. Prior to injection into the anolyte  120  the sludge feed must be neutralized with suitable acid in order to maintain the anolyte pH sufficiently low to avoid anodic production of potassium chlorate. Furthermore, a small amount of water from the BHP will evaporate in the oxygen generator  20 , and together with a small amount of unreacted chlorine, will be lost from the regeneration system by being entrained in the singlet oxygen stream  46 . It is estimated that about 0.1% of water inventory and 0.05% of chlorine inventory will be lost from the system in this manner every hour. Excess water in the BHP loop is removed by the concentrator  99 . Water and chlorine monitoring in the system will allow for the injection of water into the recirculating anolyte liquor. Injection of suitable acid is required to maintain the pH of the anolyte. Injection of HCl acid into BHP liquor replenishes chlorine lost from the system and helps to control alkalinity of the BHP liquor.  
         [0047]    Operational experience with electrolytic cells for electrosynthesis of alkaline hydrogen peroxide suggests that a small fraction of the O 2 H − anions produced by the cathode is destroyed within the cathode either by thermal decomposition or by parasitic reactions. As a result, the molar ratio of H 2 O 2  to KOH in the product liquor drained from the cathode is somewhat less than 1, as is theoretically predicted by the reactions in equations 3 and 4 in FIG.  4 . Prior art indicates that for optimum operation of COIL, the BHP liquor provide to the oxygen generator  20  should not contain significant concentrations of OH − anions. This means that the product of the cathodic reduction of oxygen in cell  100  is more alkaline than desired for optimum performance of COIL. One way to handle this situation is to allow the BHP liquor feed into the singlet oxygen generator  20  to become more alkaline and suffer with the consequential penalty of reduced laser power output of the COIL  10 . Improved COIL  10  performance is achieved by raising the ratio of H 2 O 2  to KOH to at least about 1 through any appropriate method comprising adding a small amount of HCl acid to the BHP product liquor of cell  100  or adding a small amount of neutral H 2 O 2  to the BHP product liquor of cell  100 . Addition of H 2 O 2  can be accomplished either by injection of commercially available highly concentrated H 2 O 2  or by flowing the BHP liquor from cell  100  through the middle compartment of a three compartment peroxide generation cell producing neutral peroxide H 2 O 2  such as that disclosed in the U.S. Pat. No. 4,384,931.  
         [0048]    Prior art has established that COIL can operate more efficiently with BHP where most, or all of the hydrogen atoms have been replaced by deuterium (D). The resulting basic deuterium peroxide is thus a solution of D 2 O 2 , KOD and KCl in D 2 O. However, prior art did not provide for closed loop regeneration of the basic deuterium peroxide such as the process disclosed herein, and a small scale manufacture of D 2 O 2  and KOD to supply the open-loop system of prior art was not economically feasible. Modification of the process disclosed herein to accommodate production of said basic deuterium peroxide is, therefore, another advantage which said process provides for continuous operation of COIL laser.  
         [0049]    Numerous variations and modifications exist to the preferred embodiment described herein. For example, the cell  100  which produces both Cl 2  and BHP in a single hardware unit can be replaced with two separate cells; the first cell for production of Cl 2  and KOH, and the second cell for production of BHP using KOH product from the first cell as a feedstock. Said cell for production of Cl 2  and KOH is a chlor-alkali cell preferably employing an oxygen cathode to suppress cathodic generation of unwanted hydrogen and to reduce cell voltage. A suitable cell of this type has been disclosed by McIntyre in the U.S. Pat. No. 4,927,509. Alternatively, a conventional chlor-alkali cell with cathodic production of hydrogen can be used. A suitable cell for production of BHP from oxygen and aqueous KOH feedstock is disclosed in U.S. Pat. No. 6,004,449 entitled “Method of Operating Electrolytic Cell To Produce Highly Concentrated Alkaline Hydrogen Peroxide” to Jan Vetrovec, which is made part hereof and incorporated herein by reference. The BHP product from said cell is then concentrated by removal of water and the concentrate is added to the BHP liquor recirculating through the oxygen generator  20  of the COIL  10 . Excess KCl from said recirculating BHP liquor is used as a feedstock in the first cell. The advantage of this variant is that industry standard chlor-alkali cells and modified alkaline hydrogen peroxide cells can be used in lieu of the “combined” cell  100  which requires design and fabrication of new hardware. However, the disadvantages of this variant, namely increased system complexity, increased capital cost, and increased consumption of electrical power appear to outweigh its advantages.  
         [0050]    Another class of variants exists wherein the continuous loop of depleted and regenerated BHP is made into semi-continuous or even a discontinuous (batch type) process. While such an arrangement may make it easier to balance the flows and, possibly allow production and accumulation of BHP and Cl 2  while the laser is not operating, requirements for additional holding tanks and increased system complexity are deemed to outweigh apparent advantages.  
         [0051]    The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.