The possibility of stable generation of intense characteristic Cs radiation upon electronic excitation of a Mo anode target heat treated in Cs and O2 vapors is demonstrated. The radiation source is a microfocus transmission type X-ray tube with a beryllium window and an S20 photocathode. A Cs-Mo-O layer is formed on the initial target in the form of a 1-µm-thick Mo film during heat treatment. The L and K spectral series are measured in an anode—cathode voltage range of 10—47 kV. A stable generation mode is observed at an electron flux power density up to 600 W/cm2. The energy of the Cs Kβ spectral line is in the region of photoabsorption peaks of the I and Xe atoms, which are widely used in the composition of contrast agents for medical diagnostics. This allows obtaining two- and three-dimensional images with the maximum contrast.

This paper describes the selection of deaccelerating films made of aluminum of various thicknesses (300–500 nm) and intended for deacceleration of electrons (with an energy of tens of kiloelectron volts to tens of electron volts) in the developed new generation picosecond dissectors. The designed dissectors should be different by a higher temporal resolution as compared to the maximum reached (~20 ps) in LI-602 dissecting image-tube converters used for diagnosing synchrotron radiation. This paper also presents the results of comparative measurements of emission characteristics of manufactured films in the models of image-tube converters similar in design to a PIF-01/S1 device, which is the basis of the developed dissectors and which provides the maximum temporal resolution of up to 1 ps in the streak mode with the streak speed of ~1010 cm/s. It is established that, when the energy of the incident electron beam equals 10 to 12 keV, the optimum thickness of the deaccelerating aluminum film is 400 nm with the effective secondary emission coefficient equal to 0.7.

When replacing the conventional “slow” luminescent screens (P20, P43) in picosecond image tubes by the “fast” ones (P46, P47), we found an increase in the decay time of “fast” cathodoluminophors (by a factor of 2–5) with increasing the number (from one to a hundred) of measured pulses. The consideration of the detected effect makes it possible to correct the problem statement in developing picosecond dissectors for recording repeated signals in the accumulation mode (e.g., synchrotron radiation).

The well-established PIF-01/S1/P43 picosecond streak tube, designed 30 years ago and still manufactured at the A.M. Prokhorov General Physics Institute, was modified by replacing its traditional P43 phosphor screen with a P47 one having approximately three orders of magnitude shorter decay time. The experimental measurements of this decay time were provided by PIF-01/S1/P47 image tube photocathode irradiation either with a single or a train of 8 ps laser pulses separated by 8 ns from each other at a 1.08 mu m wavelength. The results of our preliminary measurements of P47-BH phosphor (manufactured by Phosphor Technology Ltd) indicate the possibility of employing the PIF-01/S1/P47 streak tube for synchrotron diagnostics at a units megahertz repetition rate without the negative influence of 'ghost images' from the previous streak records.

It is shown that the LFS-3 crystal installed as a luminescent screen in a picosecond image tube provides the shortest afterglow time in comparisonwith all other fast-damping luminescent screens such as Y3Al5O12:Ce, Y2SiO5:Ce, and others we previously tested under similar conditions. The LFS-3 crystal exposed to single 8-ps pulses of 12–15-keV electrons shows the luminescence decay time no more than 250 ns by the level of 10-2 of the maximum.

To improve operation parameters (S/N ratio, dynamics range, time resolution, etc.) of picosecond streak tubes, the traditional P20/P43 phosphor screens can be replaced by the others (P46/P47) having much faster decay time of the luminescence output. We provide comparative dynamic measurements of the home-made phosphor screens inside the picosecond PIF-01 streak tubes under illumination of their photocathodes by a single picosecond laser pulse or a train of picosecond laser pulses. We show that the shortest measured decay time for made-in-Russia phosphor screens (Y3Al5O12:Ce) is close to several hundreds of nanoseconds not only at a half-intensity level but also at a level of 10−3 and even smaller. Furthermore, the photoelectron-to-photon conversion factor is not drastically smaller than in the traditional phosphor materials. This means that application of streak tubes supplied with fast-response phosphor screens may substantially improve the tube capabilities in the accumulation mode, and this is very important for time-resolved diagnostics of electron bunches in accelerators, where continuous accumulation of repetitive signals is needed.

In the present communication we describe the design of the sub-100 fs streak-tube that may be used for commercial streak cameras manufacturing. Careful attention is paid to preparing of a very smooth input photocathode substrate on which a low surface resistance (1-5 Ohm/) photocathode of S-1 type is deposited. Our estimations have shown that the photocathode surface roughness of about tens of nanometers may restrict the ultimate time resolution at the level of 100 fs. This is the reason why the photocathode substrate surface has to be smooth within the units of nanometers. The curvature of the photocathode surface is also very important to compensate the difference in the time-of-flight of electrons emitted from the central and peripheral photocathode areas. Further modernization was conducted with a photocathode-accelerating mesh assembly. The assembly may operate with 2 - 3 ns (FWHM) electrical pulses of 12 - 15 kV amplitude. In order to improve the S/N ratio in the streaked images, a shuttering system was incorporated inside the tube. As the result, a completely new femtosecond streak tube of PV-FS-M type was designed, manufactured, and tested.

The paper reports on the development of a new streak image tube with accelerating mesh and large (18 mm) photocathode work area. The tube's temporal resolution is close to one picosecond. To govern photoelectronic images the tube possesses shutter and deflector plates. Its geometric design allows uniform spatial resolution (more than 25 lp/mm) along the entire photocathode work area at 1.3 electron-optical magnification and negligibly small distortion. Being a continuation of the well-known PV and PIF - type streak image tubes developed in due time in GPI, the tube represents a promising tool for taking pictures of ultrafast processes in wide radiation spectrum range.

In contrast to the conventional image intensifier with large work area, a streak image tube should possess additional important feature - the comparatively small temporal distortion at the entire work area of the photocathode. With this additional engineering restriction taken into account, a novel small-size meshless streak image tube has been developed by means of numerical optimization. The tube with 25-mm wide work area contains a pair of deflection plates to sweep the electron image along the 25 mm output phosphor screen that is separated by 100 mm from the photocathode. The electron image can be shuttered with a 300 V blanking electric pulse. Electron-optical magnification of the tube is unit; spatial resolution reaches 30 lp/mm over the entire photocathode work area; temporal resolution lies in the 20 - 50 ps range, depending on the accelerating voltage (6 - 15 kV).

New generation of streak tubes intended for single-shot and synchroscan operations with femtosecond time resolution was computer modelled, designed, manufactured, tested and adopted for further application in laser research. The developed PV-FS type tubes provide close to 100 fs-time resolution in single-shot streak mode. It is important to note that the PV-FS tubes may be equipped with Peltier cooled S1-photocathodes and their spectral sensitivity may cover the range of 115 - 1550 nm. The developed photocathodes have very low surface resistance (tens of Ohm per square unit). New tubes offer a high (more than 50 line pairs/mm) spatial resolution when recording ultrafast optical images with femtosecond time resolution. Due to keeping the PV-FS external geometry similar to the well-known PV-type tubes it becomes possible to install new devices into available streak cameras (AGAT, Imacon 500, etc.).

The composition of residual gases in streak tubes has been measured. The outgassing at supply of electrical voltage to the streak tube, at heating of Cr2O3 layer and at glass melting were investigated. The EBI fluctuations at pressure of 2x10(-8) Torr and 10(-6) Torr in streak tubes were examined.

A variety of streak/framing/synchroscan image tubes are now under design and manufacturing in the Department of Photoelectronics, General Physics Institute. Among them are: a series of the well-known PV001 image tubes introduced into wide practice since 1978, a set of more advanced PIF001 tubes originally designed in 1979, specially developed femtosecond streak tubes of BSV-type, which were initially proposed in 1987, and finally a number of PF-type tubes placed in service last year. The whole set of these image tubes may cover the spectral range from 115 nm up to 1.55 micrometers , providing maximum sensitivity of 0.5 (mu) A/W at 1.55 micrometers (S1/IR) and up to 3 mA/W at 900 nm (S25/ER). Various input photocathode windows may be used: fiber-optics or borosilicate substrates which blue transparency starts at 350 nm. UV-glass windows (> 200 nm), MgF2 input window (> 115 nm). All tubes with photocathode- accelerating mesh geometry have photocathode area of 6 mm in diameter, while the tubes in non-mesh configuration (PV and PF0 have a rectangular photocathode area of not less than 4 mm by 18 mm. The described tubes may be supplied with any type of phosphor screen (red, orange, blue, green) deposited onto fiber-optics faceplate.

A variety of streak/framing/synchroscan image tubes are now under design and manufacturing in the Department of Photoelectronics, General Physics Institute. Among them are: a series of the well-known PV001 image tubes introduced into wide practice since 1978, a set of more advanced PIF001 tubes originally-designed in 1979, specially developed femtosecond streak tubes of BSV-type, which were initially proposed in 1987, and finally a number of PF-type tubes placed in service last year. The whole set of these image tubes may cover the spectral range from 115 nm up to 1.55 mu m, providing maximum sensitivity of 0.5 mu A/W at 1.55 mu m (S1/IR) and up to 3 mA/W at 900nm (S25/ER). Various input photocathode windows may be used: fibre-optics or borosilicate substrates which blue transparency starts at 350 nn, UV-glass windows (>200 nm), MgF2 input window (>115 nn). All tubes with photocathode-accelerating mesh geometry have photocathode area of 6mm in diameter, while the tubes in non-mesh configuration (PV and PF) have a rectangular photocathode area of not less than 4mm by 18mm. The described tubes may be supplied with any type of phosphor screen (red, orange, blue, green) deposited onto fibre-optics faceplate.

Current GPI status on femtosecond cameras and diffractometers research and development is overviewed. Discussed are the key components of the femtosecond diffractometer which is now under design. The first experimental prototype of 20-40 kV, femtosecond photoelectron diffractometer is computer designed, manufactured and tested.