NOVELTY - A system for mixed production of hydrogen gas, carbon materials and carbon monoxide gas, comprises a reaction chamber for chemical vapor deposition, where the reaction chamber includes an upwardly extending wall defining a cavity having a lower portion and an upper portion with the upper portion having a volume capacity larger than a volume capacity of the lower portion such that longer retention time is provided for material with lower density and materials with different densities can achieve same or similar circulating speed in the reaction chamber.    USE - The systems and methods are useful for mixed production of hydrogen gas, carbon materials and carbon monoxide gas (claimed).    ADVANTAGE - The system has higher and efficient hydrogen production due to longer and higher catalytic activity.    DETAILED DESCRIPTION - A system for mixed production of hydrogen gas, carbon materials and carbon monoxide gas, comprises a reaction chamber for chemical vapor deposition, where the reaction chamber includes an upwardly extending wall defining a cavity having a lower portion and an upper portion with the upper portion having a volume capacity larger than a volume capacity of the lower portion such that longer retention time is provided for material with lower density and materials with different densities can achieve same or similar circulating speed in the reaction chamber, and where the wall defines an internal surface provided with a set of protrusions extending into the cavity for reducing horizontal cross section area of the cavity at it. INDEPENDENT CLAIMS are:    (1) a method for producing hydrogen, comprising: (a) providing a vapor chamber having a bed of fluidized solid bed particles; (b) feeding a combination of a metal catalyst and a catalyst support into the fluidized solid bed particles; (c) introducing an inflow gas, at least a part of which is hydrocarbon gas, into the vapor chamber; and (d) providing heating to the vapor chamber until hydrogen is produced from the dissociation of the gas; and    (2) a system for producing hydrogen comprising: (a) a vapor chamber having a bed of fluidized solid particles in it; (b) a metal catalyst feeder for feeding metal catalyst and a catalyst support into the vapor or onto the fluidized solid particle bed; (c) a gas supply arranged to introduce an inflow gas into the vapor chamber; and (d) a heating system arranged to provide heating to the vapor chamber; where the inflow gas includes at least a portion of hydrocarbon gas; and where the system is configured to produce hydrogen from the dissociation of the inflow gas.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of a vapor chamber system.    System for producing hydrogen (5)    Fluidized bed reactor (10)    Fluidized solid bed (15)    External source (20)    Charging device (25)    Heat exchanger (30)    First cyclonic device (35)    Second cyclonic device (40)    Channel (45, 50)    Gas distributor (62)    Me-catalyst beam (63)    Spray (65)    Supply (75)